Research

12 pages, 2146 KiB

Open AccessArticle

Sources Causing Long-Term and Seasonal Changes in Combustion-Derived Particulate Matter in the Urban Air of Sapporo, Japan, from 1990 to 2002

by Kazuichi Hayakawa, Shigekatsu Sakai and Tomoko Akutagawa

Atmosphere 2023, 14(4), 646; https://doi.org/10.3390/atmos14040646 - 29 Mar 2023

Viewed by 999

Abstract

Fifty-one samples were collected seasonally to estimate the amounts of total suspended particulate (TSP) in Sapporo, Japan, from 1990 to 2002. The atmospheric concentration of combustion-derived particulate (P_c) was calculated based on the NP method using 1-nitropyrene and pyrene. The atmospheric [...] Read more.

Fifty-one samples were collected seasonally to estimate the amounts of total suspended particulate (TSP) in Sapporo, Japan, from 1990 to 2002. The atmospheric concentration of combustion-derived particulate (P_c) was calculated based on the NP method using 1-nitropyrene and pyrene. The atmospheric TSP and P_c concentration ranges were between 31–121 µg m⁻³ of air (Mean ± standard deviation (SD) = 58.2 ± 20.2 µg m⁻³) and 31–121 µg m⁻³ (Mean ± SD = 8.2 ± 6.0 µg m⁻³), respectively. First-order linear regression equations suggested that the P_c fraction decreased faster than TSP. The highest and lowest P_c concentrations were observed in winter and summer, respectively, whereas the highest and lowest TSP concentrations were observed in spring and winter, respectively. The largest and smallest P_c/TSP concentration ratios were observed in winter (0.324) and summer (0.075), respectively. The seasonal fractions of high-temperature combustion-derived particulate (P_h) in P_c ranged from 0.56 (winter) to 0.75 (summer), suggesting that the contribution of vehicle emissions to P_c was always larger than those of coal and biomass combustion. The sources of long-term and seasonal change in P_c were elucidated by analyzing organic source markers. Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs), nitropolycyclic aromatic hydrocarbons (NPAHs) and hopanes showed long-term and seasonal changes similar to those of P_c, although biomarkers of biomass and coal combustion, such as levoglucosan, mannosan, and galactosan were not as strongly correlated. These results suggest that the change in the P_c concentration was mainly affected by vehicle emissions rather than by coal and biomass combustion or secondary pollutant formation. The decrease in the P_c over the study period was mainly a result of the Japanese particulate matter/NOx regulations on vehicle exhaust. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

19 pages, 2776 KiB

Open AccessArticle

Race and Street-Level Firework Legalization as Primary Determinants of July 4th Air Pollution across Southern California

by Shahir Masri, Leonel Flores, Jose Rea and Jun Wu

Atmosphere 2023, 14(2), 401; https://doi.org/10.3390/atmos14020401 - 19 Feb 2023

Cited by 2 | Viewed by 1997

Abstract

Air pollution is a major public health threat that is associated with asthma, cardiovascular disease, respiratory disease and all-cause mortality. Among the most important acute air pollution events occurring each year are celebrations involving fireworks, such as the 4th of July holiday in [...] Read more.

Air pollution is a major public health threat that is associated with asthma, cardiovascular disease, respiratory disease and all-cause mortality. Among the most important acute air pollution events occurring each year are celebrations involving fireworks, such as the 4th of July holiday in the United States. In this community-engaged study, academic partners and residents collaborated to collect indoor and outdoor PM_2.5 concentration measurements in the disadvantaged city of Santa Ana, California, using low-cost AtmoTube sensor devices before, during and after the July 4th firework celebration, while also examining July 4th data extracted from the PurpleAir sensor network across over a hundred other cities in southern California. Average outdoor PM_2.5 concentrations on July 4th were found to be three-to-five times higher than baseline, with hourly concentrations exceeding 160 μg/m³. Outdoor averages were roughly 30% to 100% higher than indoor levels. The most polluted cities exhibited 15-times higher PM_2.5 levels compared with the least contaminated cities and were often those where household-level fireworks were legal for sale and use. Race/ethnicity was found to be the leading predictor of July 4th-related air pollution across three counties in southern California, with greater PM_2.5 being associated with higher proportions of Hispanic residents and lower proportions of White residents. The findings from this study underscore the importance of environmental justice as it relates to firework-related air pollution exposure, and the critical role city- and county-level firework policies play in determining exposure. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

15 pages, 2360 KiB

Open AccessArticle

Mind the Large Gap: Novel Algorithm Using Seasonal Decomposition and Elastic Net Regression to Impute Large Intervals of Missing Data in Air Quality Data

by Lakmini Wijesekara and Liwan Liyanage

Atmosphere 2023, 14(2), 355; https://doi.org/10.3390/atmos14020355 - 10 Feb 2023

Cited by 2 | Viewed by 1658

Abstract

Air quality data sets are widely used in numerous analyses. Missing values are ubiquitous in air quality data sets as the data are collected through sensors. Recovery of missing data is a challenging task in the data preprocessing stage. This task becomes more [...] Read more.

Air quality data sets are widely used in numerous analyses. Missing values are ubiquitous in air quality data sets as the data are collected through sensors. Recovery of missing data is a challenging task in the data preprocessing stage. This task becomes more challenging in time series data as time is an implicit variable that cannot be ignored. Even though existing methods to deal with missing data in time series perform well in situations where the percentage of missing values is relatively low and the gap size is small, their performances are reasonably lower when it comes to large gaps. This paper presents a novel algorithm based on seasonal decomposition and elastic net regression to impute large gaps of time series data when there exist correlated variables. This method outperforms several other existing univariate approaches namely Kalman smoothing on ARIMA models, Kalman smoothing on structural time series models, linear interpolation, and mean imputation in imputing large gaps. However, this is applicable only when there exists one or more correlated variables with the time series with large gaps. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

17 pages, 831 KiB

Open AccessArticle

PM₁₀ Resuspension of Road Dust in Different Types of Parking Lots: Emissions, Chemical Characterisation and Ecotoxicity

by Ismael Casotti Rienda, Célia A. Alves, Teresa Nunes, Marlene Soares, Fulvio Amato, Ana Sánchez de la Campa, Nóra Kováts, Katalin Hubai and Gábor Teke

Atmosphere 2023, 14(2), 305; https://doi.org/10.3390/atmos14020305 - 03 Feb 2023

Cited by 8 | Viewed by 2422

Abstract

The thoracic fraction of road dust (PM₁₀) was measured for the first time in Portugal in parking areas, both outdoors and indoors, with the aim of completing existing studies carried out in active lanes of various roads. An in situ resuspension [...] Read more.

The thoracic fraction of road dust (PM₁₀) was measured for the first time in Portugal in parking areas, both outdoors and indoors, with the aim of completing existing studies carried out in active lanes of various roads. An in situ resuspension chamber was used to collect a total of 23 samples in three parking areas of Aveiro, whilst the laboratory procedures included determination of carbonaceous content (OC and EC) by a thermo-optical technique, elemental composition by ICP-MS and ICP-OES after acid digestion, and the Aliivribrio fisherii bioluminescent bacteria ecotoxicity bioassay. Dust loadings (DL10) obtained were 18.5 ± 9.8 mg PM₁₀ m⁻², in outdoor parking, and 1.8–23.7 mg PM₁₀ m⁻² for indoor parking, corresponding to emission factors of 476 and 75–589 mg veh⁻¹ km⁻¹, respectively. OC represented 9–30 % of PM₁₀ for the indoor parking areas. However, for the outdoor samples, the high iron oxide content jeopardised the OC-EC separation. In those samples, carbonates accounted for 10.0 ± 3.3% of the PM₁₀ mass. The analysis of elemental components focused on major elements (Al, Ca, Fe, K, and Mg) as well as minor elements. The total mass fraction of element oxides accounted for 27.1% (outdoor) and 23.6–34.3% (indoor). Σ_PAH calculated for all parking areas accounted for 8.38–36.9 μg g⁻¹ PM₁₀. The ecotoxicological bioassay showed that all aqueous solutions were toxic to bioluminescent bacteria, whereas no clear correlations could be made with specific component groups, with the exception of Σ_PAH and EC₅₀. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

19 pages, 1698 KiB

Open AccessArticle

GHG Global Emission Prediction of Synthetic N Fertilizers Using Expectile Regression Techniques

by Kaoutar Benghzial, Hind Raki, Sami Bamansour, Mouad Elhamdi, Yahya Aalaila and Diego H. Peluffo-Ordóñez

Atmosphere 2023, 14(2), 283; https://doi.org/10.3390/atmos14020283 - 31 Jan 2023

Cited by 4 | Viewed by 2423

Abstract

Agriculture accounts for a large percentage of nitrous oxide (

N_{2} O

) emissions, mainly due to the misapplication of nitrogen-based fertilizers, leading to an increase in the greenhouse gas (GHG) footprint. These emissions are of a direct nature, released straight into [...] Read more.

Agriculture accounts for a large percentage of nitrous oxide (

N_{2} O

) emissions, mainly due to the misapplication of nitrogen-based fertilizers, leading to an increase in the greenhouse gas (GHG) footprint. These emissions are of a direct nature, released straight into the atmosphere through nitrification and denitrification, or of an indirect nature, mainly through nitrate leaching, runoff, and

N_{2} O

volatilization processes.

N_{2} O

emissions are largely ascribed to the agricultural sector, which represents a threat to sustainability and food production, subsequent to the radical contribution to climate change. In this connection, it is crucial to unveil the relationship between synthetic N fertilizer global use and

N_{2} O

emissions. To this end, we worked on a dataset drawn from a recent study, which estimates direct and indirect

N_{2} O

emissions according to each country, by the Intergovernmental Panel on Climate Change (IPCC) guidelines. Machine learning tools are considered great explainable techniques when dealing with air quality problems. Hence, our work focuses on expectile regression (ER) based-approaches to predict

N_{2} O

emissions based on N fertilizer use. In contrast to classical linear regression (LR), this method allows for heteroscedasticity and omits a parametric specification of the underlying distribution. ER provides a complete picture of the target variable’s distribution, especially when the tails are of interest, or in dealing with heavy-tailed distributions. In this work, we applied expectile regression and the kernel expectile regression estimator (KERE) to predict direct and indirect

N_{2} O

emissions. The results outline both the flexibility and competitiveness of ER-based techniques in regard to the state-of-the-art regression approaches. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

14 pages, 1881 KiB

Open AccessArticle

Biofiltration of Waste Gas Containing Cyclohexanol, Cyclohexanone and Butanol

by Agnieszka Tabernacka

Atmosphere 2023, 14(2), 254; https://doi.org/10.3390/atmos14020254 - 28 Jan 2023

Cited by 1 | Viewed by 1143

Abstract

The aim of the study was to determine the efficiency of a biofilter treating waste gas containing a mixture of cyclohexanol (CHXOH), cyclohexanone (CHXO) and butanol (BL) and to assess the impact of the process parameters on the microorganisms and their enzymatic activities. [...] Read more.

The aim of the study was to determine the efficiency of a biofilter treating waste gas containing a mixture of cyclohexanol (CHXOH), cyclohexanone (CHXO) and butanol (BL) and to assess the impact of the process parameters on the microorganisms and their enzymatic activities. The biofilter was packed with compost made from green waste mixed with compost made from municipal wastes and polyethylene carriers with immobilized biomass of bacteria. A linear correlation between pollutant loading rate and biofilter elimination capacity was obtained. At a hydraulic load of the biofilter bed of 127.3 m³/(m³ × h), the average elimination capacities were 14.6 g CHXOH/(m³ × h), 3.6 g CHXO/(m³ × h) and 3.8 g BL/(m³ × h). The microbiological and enzymatic analyses of the biofilter bed indicated that high loading rates of pollutants can have significant effects on microbial growth and enzymatic activity. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

17 pages, 3974 KiB

Open AccessArticle

Can Air Quality Gas Sensors Be Used for Emission Monitoring of Small-Scale Local Air Pollution Sources? Pilot Test Evaluation

by Pavel Buček, Jiří Bílek, Petr Maršolek and Ondřej Bílek

Atmosphere 2023, 14(2), 248; https://doi.org/10.3390/atmos14020248 - 27 Jan 2023

Viewed by 1698

Abstract

In recent years we have seen a growing number of applications that use various sensory measurements of physicochemical features. Within the research project “Research on the identification of combustion of unsuitable fuels and systems of self-diagnostics of boilers combustion solid fuels for domestic [...] Read more.

In recent years we have seen a growing number of applications that use various sensory measurements of physicochemical features. Within the research project “Research on the identification of combustion of unsuitable fuels and systems of self-diagnostics of boilers combustion solid fuels for domestic heating”, the authors tested and evaluated the possible use of an air quality monitoring sensor unit for the measurement of operating parameters of solid fuel burning boilers and stoves. In the Czech Republic, programs to support citizens in the replacement of domestic boilers of poor combustion quality have been subsidized for several years. Unfortunately, no assessment of the impact of subsidies on air quality has been carried out. However, the increased pollutant emissions due to improper use of domestic boilers are supposed to be one of the greatest problems with domestic boilers. Hence, providing users with real-time feedback may lead to changes in combustion conditions and consequently to a reduction in air pollution. We focus on sensory measurements of CO, CO₂, NO, and VOCs as compounds that correspond to the operating conditions of the combustion process. The research included sampling, construction of the flue gas dilution duct, and the influence of direct measurement on the service life of the sensors. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

11 pages, 228 KiB

Open AccessArticle

A Survey on Toxic Volatile Organic Compounds (VOCs): Toxicological Profiles, Health Exposure Risks, and Regulatory Strategies for Mitigating Emissions from Stationary Sources in Taiwan

by Wen-Tien Tsai

Atmosphere 2023, 14(2), 242; https://doi.org/10.3390/atmos14020242 - 26 Jan 2023

Cited by 6 | Viewed by 1770

Abstract

With the revision of the Air Pollution Control Act in Taiwan announced on 1 August 2018, several provisions or regulations have been added to strengthen the control of hazardous air pollutants (HAPs) from stationary sources. Therefore, this paper conducted a survey of sixty [...] Read more.

With the revision of the Air Pollution Control Act in Taiwan announced on 1 August 2018, several provisions or regulations have been added to strengthen the control of hazardous air pollutants (HAPs) from stationary sources. Therefore, this paper conducted a survey of sixty toxic volatile organic compounds (VOCs) designated as HAPs in Taiwan and also performed a comparison between some developed countries (i.e., the USA, Japan, and Korea) using the latest databases issued by the relevant agencies/organizations. Furthermore, these designated HAPs were reviewed by their carcinogenic classifications and occupational exposure limits. Finally, the regulatory measures for controlling the emissions of toxic VOCs from stationary sources in Taiwan were addressed to echo the public concerns about their human health risk. Except for trichloroacetic acid, the designated toxic VOCs in Taiwan are included in the list of HAPs in the USA. By comparison, the number of designated HAPs is obviously higher than those in Japan and Korea. Based on the carcinogen classification by the International Agency for Research on Cancer (IARC), the toxic VOCs as confirmed human carcinogens (Group 1) include benzene, benzidine, 1,3-butadiene, 1,2-dichloroproane, ethylene oxide, formaldehyde, 4,4-methylene bis(2-chloroaniline), trichloroethylene, and vinyl chloride. To achieve the purpose of protecting public health, the follow-up control actions of HAPs from stationary sources in Taiwan involved regulatory countermeasures, including the establishment of emission limits, reporting systems, reduction plans for potential high-risk areas or plants, the incentive of an air pollution fee levy, as well as an ambient air concentration monitoring network. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

18 pages, 258 KiB

Open AccessArticle

Research on the Spatial Effects of Green Process Innovation, Environmental Regulation, and Precipitation on Environmental Air Pollution

by Jingkun Zhou, Yating Li, Juan Tian and Zhifei Ma

Atmosphere 2023, 14(2), 211; https://doi.org/10.3390/atmos14020211 - 19 Jan 2023

Cited by 2 | Viewed by 1311

Abstract

In recent years, air pollution events have occurred frequently in China and have had serious impacts on people’s work and life. The research objective of the article is to find out the spatial effects of green process innovation, environmental regulation, rainfall, and pollution [...] Read more.

In recent years, air pollution events have occurred frequently in China and have had serious impacts on people’s work and life. The research objective of the article is to find out the spatial effects of green process innovation, environmental regulation, rainfall, and pollution from industrial development on air pollution by compiling a development index of the air pollution industry and constructing spatial autoregression and spatial Durbin models. The study found that green technology innovation significantly reduced sulfur dioxide emissions and fog haze pollution. The development of industrial air pollution is an important source of sulfur dioxide and pollutant haze and has significant spatial spillover effects. The strengthening of environmental regulations leads to a decrease in life pollution but causes a transfer of industrial pollution. Rainfall is conducive to reducing the concentrations of pollutants in the air, such as those from chimneys and smog. Policy recommendations are proposed, such as establishing different environmental policies for different green technological innovations to promote green technology innovation; constructing a joint defense control system for regional air pollution; increasing the construction of artificial wetlands in areas with serious air pollution; and creating scientific plans to coordinate the development of industry, technology, and the environment, to provide help for China to reduce the emission of atmospheric environmental pollutants. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

16 pages, 4751 KiB

Open AccessArticle

Ventilation Methods against Indoor Aerosol Infection of COVID-19 in Japan

by Motoya Hayashi, U Yanagi, Yoshinori Honma, Yoshihide Yamamoto, Masayuki Ogata, Koki Kikuta, Naoki Kagi and Shin-ichi Tanabe

Atmosphere 2023, 14(1), 150; https://doi.org/10.3390/atmos14010150 - 10 Jan 2023

Cited by 3 | Viewed by 3149

Abstract

The importance of effective ventilation as one of the measures against COVID-19 is widely recognized worldwide. In Japan, at the early stage of the pandemic, in March 2020, an official announcement was made about basic ventilation measures against COVID-19. WHO also used the [...] Read more.

The importance of effective ventilation as one of the measures against COVID-19 is widely recognized worldwide. In Japan, at the early stage of the pandemic, in March 2020, an official announcement was made about basic ventilation measures against COVID-19. WHO also used the term “long-range aerosol or long-range airborne transmission” for the first time in December 2021. Based on the aerosol infection control measures before 2021 by the Japanese government, we conducted experiments on methods related to partition placement as an element of effective ventilation methods. In July 2022, the governmental subcommittee on Novel Coronavirus Disease Control provided an emergent proposal about effective ventilation methods to prevent two types of aerosol infection; infection by large aerosol on the air current and infection by small floating aerosol diffusion in a room. They also showed the way of setting droplet prevention partitions, which do not block off ventilation based on this investigation’s results. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

19 pages, 1471 KiB

Open AccessArticle

A Comparative Study of Air Pollutant Concentrations before the COVID-19 Pandemic and in the New Normal in the Región de Murcia (Spain)

by Marta Doval-Miñarro and María Carmen Bueso

Atmosphere 2023, 14(1), 147; https://doi.org/10.3390/atmos14010147 - 09 Jan 2023

Cited by 2 | Viewed by 1388

Abstract

The management of the COVID-19 pandemic, which required global lockdowns and mobility restrictions, positively impacted air quality (especially the concentrations of primary pollutants). With the progressive return to normal activity during the last few months of 2020 and 2021, air pollutant concentrations were [...] Read more.

The management of the COVID-19 pandemic, which required global lockdowns and mobility restrictions, positively impacted air quality (especially the concentrations of primary pollutants). With the progressive return to normal activity during the last few months of 2020 and 2021, air pollutant concentrations were expected to rise again. In this work, together with meteorological conditions and traffic intensity, the concentrations of NO, NO

_{2}

, O

_{3}

, PM

_{10}

, and SO

_{2}

measured at three different locations (urban, industrial, and rural) in southeast Spain, from January 2016 to December 2021, were analyzed. For the three locations, PM

_{10}

concentrations did not change significantly in 2020 or 2021. SO

_{2}

concentrations did not experience changes at the industrial site in 2020 or 2021, but SO

_{2}

concentrations did slightly increase in five months of 2021 in the urban location (with a maximum monthly average concentration of 11

μ

g·m

^{- 3}

). In 2020, NO and NO

_{2}

concentrations were, in general, lower than those measured in previous years (2016–2019). Interestingly, at the urban site (San Basilio), the levels of NO and NO

_{2}

were significantly lower in 2021 than in 2020 despite the higher traffic intensity in 2021. While the concentrations of NO and NO

_{2}

decreased, in VOC-limited areas, O

_{3}

concentrations increased. This was clearly observed at the industrial and the urban sites. Despite the increase, O

_{3}

concentrations were still below the European O

_{3}

target value for the protection of human health. An analysis of new registrations of EVs and HEVs in the latter years and their impact on the vehicle fleet of Murcia and, subsequently, on road emissions was carried out. Regardless of the steep increase in environmentally friendly vehicles in 2021, their share of the vehicle fleet is still negligible; thus, the lower concentrations of NO and NO

_{2}

are likely due to more favorable weather conditions in 2021 than in 2020. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

11 pages, 1375 KiB

Open AccessArticle

Seasonal Variations of Particulate Matter Capture and the Air Pollution Tolerance Index of Five Roadside Plant Species

by Huong-Thi Bui, Na-Ra Jeong and Bong-Ju Park

Atmosphere 2023, 14(1), 138; https://doi.org/10.3390/atmos14010138 - 08 Jan 2023

Cited by 2 | Viewed by 3167

Abstract

Particulate matter (PM) is the most dangerous type of air pollutant and is harmful to human health. Plants can be used as a biofilter to remove PM from the atmosphere and improve air quality. In this study, we used the air pollution tolerance [...] Read more.

Particulate matter (PM) is the most dangerous type of air pollutant and is harmful to human health. Plants can be used as a biofilter to remove PM from the atmosphere and improve air quality. In this study, we used the air pollution tolerance index and four leaf traits of five different plant species commonly used in landscaping in Korea to determine which plants are best suited to remove PM from the atmosphere in roadside areas in spring, summer, and autumn. We found that the PM concentrations in the atmosphere impacted the amount of PM accumulated in the plants, with increased PM accumulation during periods of increased environmental PM levels on the roadside. Euonymus japonicus, and Euonymus alatus accumulated the highest amount of PM and had the highest tolerance levels to air pollution. Thus, these species could be suitable for use in areas with high PM concentrations to improve air quality. We also found that shrubs were more effective in accumulating PM than trees and recommend that shrubs and trees be used together to further increase the amount of PM removed from the atmosphere in urban areas. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

19 pages, 4330 KiB

Open AccessArticle

The Use of Multilayer Perceptrons to Model PM_2.5 Concentrations at Air Monitoring Stations in Poland

by Szymon Hoffman and Rafał Jasiński

Atmosphere 2023, 14(1), 96; https://doi.org/10.3390/atmos14010096 - 01 Jan 2023

Cited by 5 | Viewed by 1487

Abstract

The biggest problem facing air protection in Poland is the high levels of suspended particular matter concentrations. Air monitoring reports show that air quality standards, related to PM₁₀ and PM_2.5 concentrations, are exceeded every year in many Polish cities. The PM [...] Read more.

The biggest problem facing air protection in Poland is the high levels of suspended particular matter concentrations. Air monitoring reports show that air quality standards, related to PM₁₀ and PM_2.5 concentrations, are exceeded every year in many Polish cities. The PM_2.5 aerosol fraction is particularly dangerous to human and animal health. Therefore, monitoring the level of PM_2.5 concentration should be considered particularly important. Unfortunately, most monitoring stations in Poland do not measure this dust fraction. However, almost all stations are equipped with analyzers measuring PM₁₀ concentrations. PM_2.5 is a fine fraction of PM₁₀, and there is a strong correlation between the concentrations of these two types of suspended dust. This relationship can be used to determine the concentration of PM_2.5. The main purpose of this analysis was to assess the accuracy of PM_2.5 concentration prediction using PM₁₀ concentrations. The analysis was carried out on the basis of long-term hourly data recorded at several monitoring stations in Poland. Artificial neural networks in the form of a multilayer perceptron were used to model PM_2.5 concentrations. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

17 pages, 4033 KiB

Open AccessArticle

Status of Air Pollution during COVID-19-Induced Lockdown in Delhi, India

by Harikesh Singh, Gowhar Meraj, Sachchidanand Singh, Vaibhav Shrivastava, Vishal Sharma, Majid Farooq, Shruti Kanga, Suraj Kumar Singh and Pankaj Kumar

Atmosphere 2022, 13(12), 2090; https://doi.org/10.3390/atmos13122090 - 12 Dec 2022

Cited by 6 | Viewed by 5401

Abstract

To monitor the spread of the novel coronavirus (COVID-19), India, during the last week of March 2020, imposed national restrictions on the movement of its citizens (lockdown). Although India’s economy was shut down due to restrictions, the nation observed a sharp decline in [...] Read more.

To monitor the spread of the novel coronavirus (COVID-19), India, during the last week of March 2020, imposed national restrictions on the movement of its citizens (lockdown). Although India’s economy was shut down due to restrictions, the nation observed a sharp decline in particulate matter (PM) concentrations. In recent years, Delhi has experienced rapid economic growth, leading to pollution, especially in urban and industrial areas. In this paper, we explored the linkages between air quality and the nationwide lockdown of the city of Delhi using a geographic information system (GIS)-based approach. Data from 37 stations were monitored from 12 March, 2020 to 2 April, 2020 and it was found that the Air Quality Index for the city was almost reduced by 37% and 46% concerning PM_2.5 and PM10, respectively. The study highlights that, in regular conditions, the atmosphere’s natural healing rate against anthropogenic activities is lower, as indicated by a higher AQI. However, during the lockdown, this sudden cessation of anthropogenic activities leads to a period in which the natural healing rate is greater than the induced disturbances, resulting in a lower AQI, and thus proving that this pandemic has given a small window for the environment to breathe and helped the districts of Delhi to recover from serious issues related to bad air quality. If such healing windows are incorporated into policy and decision-making, these can prove to be effective measures for controlling air pollution in heavily polluted regions of the World. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

24 pages, 11944 KiB

Open AccessArticle

Contribution of Airplane Engine Emissions on the Local Air Quality around Stuttgart Airport during and after COVID-19 Lockdown Measures

by Abdul Samad, Kathryn Arango, Ioannis Chourdakis and Ulrich Vogt

Atmosphere 2022, 13(12), 2062; https://doi.org/10.3390/atmos13122062 - 08 Dec 2022

Cited by 1 | Viewed by 1632

Abstract

Air quality investigations at airports have shown that aircrafts cause a significant increase in air pollution at and around the vicinity of the airport, which can cause adverse effects on human health. The objective of this research was to investigate the aircraft-sourced pollutant [...] Read more.

Air quality investigations at airports have shown that aircrafts cause a significant increase in air pollution at and around the vicinity of the airport, which can cause adverse effects on human health. The objective of this research was to investigate the aircraft-sourced pollutant levels at the Stuttgart airport and in the surrounding areas during and after COVID-19 lockdown measures. Three phases of stationary measurements of ultrafine particles (UFP), particulate matter (PM), black carbon (BC), CO₂, O₃, NO, and NO₂ were made at various points on the east and west sides of the airport in the extension of the airport runway. In first phase of measurement, the airport was closed for construction, and no air traffic took place. In the second phase, the airport was reopened with limited operation due to a lockdown period at the beginning of the COVID-19 pandemic. Finally, in the third phase, measurements were performed during the peak summer holiday travel season to measure the air quality during maximum air traffic, after the end of the first lockdown period. While there were fewer notable changes in the BC concentrations, coarse PM fractions, and gases across the three phases, there were significant increases in the UFP concentrations from aircraft emissions. Throughout the three phases, the peak particle concentration decreased from between 27 and 86 nm in phase 1. to between 27 and 35 nm in phase 2, to finally 11 nm in phase 3 on all days in which the aircraft plumes were measured. During flight arrivals, definite increases in UFP particle number concentration (PNC) were observed, with the majority of the particles being in the 10 nm size class. These results were measured repeatedly on both sides of the airport in the direct prolongation of the runway and even at distances of up to 3 km away in nearby neighbouring communities. While the overall PM and UFP levels are affected by vehicular traffic, the freeway measurements showed particles from aircrafts and vehicles are distinguishable using the parameters PNC and D_p. The BC concentrations were rarely influenced by aircraft activity, while only some NO and NO₂ peaks were measured depending on the consistency of the wind. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

17 pages, 2033 KiB

Open AccessArticle

A Novel Hybrid Model Combining the Support Vector Machine (SVM) and Boosted Regression Trees (BRT) Technique in Predicting PM₁₀ Concentration

by Wan Nur Shaziayani, Hasfazilah Ahmat, Tajul Rosli Razak, Aida Wati Zainan Abidin, Saiful Nizam Warris, Arnis Asmat, Norazian Mohamed Noor and Ahmad Zia Ul-Saufie

Atmosphere 2022, 13(12), 2046; https://doi.org/10.3390/atmos13122046 - 07 Dec 2022

Cited by 3 | Viewed by 1669

Abstract

The PM₁₀ concentration is subject to significant changes brought on by both gaseous and meteorological variables. The aim of this research was to explore the performance of a hybrid model combining the support vector machine (SVM) and the boosted regression trees (BRT) [...] Read more.

The PM₁₀ concentration is subject to significant changes brought on by both gaseous and meteorological variables. The aim of this research was to explore the performance of a hybrid model combining the support vector machine (SVM) and the boosted regression trees (BRT) technique in predicting the PM₁₀ concentration for 3 consecutive days. The BRT model was trained by utilizing maximum daily data in the cities of Alor Setar, Klang, and Kuching from the years 2002 to 2017. The SVM–BRT model can optimize the number of predictors and predict PM₁₀ concentration; it was shown to be capable of predicting air pollution based on the models’ performance with NAE (0.15–0.33), RMSE (10.46–32.60), R² (0.33–0.70), IA (0.59–0.91), and PA (0.50–0.84). This was accomplished while saving training time by reducing the feature size given in the data representation and preventing learning from noise (overfitting) to improve accuracy. This knowledge establishes the foundation for the development of efficient methods to prevent and/or minimize the health effects of PM₁₀ exposure on one’s health. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

16 pages, 3067 KiB

Open AccessArticle

Traffic Density and Air Pollution: Spatial and Seasonal Variations of Nitrogen Dioxide and Ozone in Jamaica, New York

by Mayra Guaman, Dawn Roberts-Semple, Christopher Aime, Jin Shin and Ayodele Akinremi

Atmosphere 2022, 13(12), 2042; https://doi.org/10.3390/atmos13122042 - 06 Dec 2022

Cited by 1 | Viewed by 1944

Abstract

Nitrogen dioxide (NO₂) and ground-level ozone (O₃) pose significant public health concerns in urban areas. This study assessed the safety level of NO₂ and described spatial and seasonal variations of NO₂ and O₃ in Jamaica Center, [...] Read more.

Nitrogen dioxide (NO₂) and ground-level ozone (O₃) pose significant public health concerns in urban areas. This study assessed the safety level of NO₂ and described spatial and seasonal variations of NO₂ and O₃ in Jamaica Center, New York, using low-cost diffusion tubes at six high-traffic (HT) and three low-traffic (LT) sites over two-week intervals in summer, winter, and fall of 2019. When annualized, the highest NO₂ level (33.90 μg/m³) was below the safety threshold (99.6 μg/m³). Mean concentrations of NO₂ samples were significantly higher at HT sites (35.79 μg/m³; 95%CI: 32.81–38.77) compared to LT sites (25.29 μg/m³; 95%CI: 11.73–28.85), p = 0.002, and during fall (38.14 μg/m³; 95%CI: 31.18–45.11) compared to winter (25.53 μg/m³; 95%CI: 20.84–30.22). There was no significant difference in O₃ levels between the fall (51.68 μg/m³; 95%CI: 44.70–58.67) and summer (46.43 μg/m³; 95%CI: 35.25–57.61), p = 0.37, and between HT sites (48.51 μg/m³; 95%CI: 40.39–56.63) and LT sites (50.14 μg/m³; 95%CI: 43.98–56.30), p = 0.79. Our results demonstrate the feasibility of low-cost air monitoring and the need for emission control policies along major corridors mainly in fall and summer, especially with the rapid commercial and economic development underway in Jamaica Center. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

22 pages, 11506 KiB

Open AccessArticle

Simulations of Organic Aerosol with CAMx over the Po Valley during the Summer Season

by Barbara Basla, Valentina Agresti, Alessandra Balzarini, Paolo Giani, Guido Pirovano, Stefania Gilardoni, Marco Paglione, Cristina Colombi, Claudio A. Belis, Vanes Poluzzi, Fabiana Scotto and Giovanni Lonati

Atmosphere 2022, 13(12), 1996; https://doi.org/10.3390/atmos13121996 - 28 Nov 2022

Cited by 2 | Viewed by 1446

Abstract

A new sensitivity analysis with the Comprehensive Air Quality Model with Extensions (CAMx) using a traditional two-product scheme (SOAP) and the newer Volatility Basis Set (VBS) algorithm for organic aerosol (OA) calculations is presented. The sensitivity simulations include the default versions of the [...] Read more.

A new sensitivity analysis with the Comprehensive Air Quality Model with Extensions (CAMx) using a traditional two-product scheme (SOAP) and the newer Volatility Basis Set (VBS) algorithm for organic aerosol (OA) calculations is presented. The sensitivity simulations include the default versions of the SOAP and VBS schemes, as well as new parametrizations for the VBS scheme to calculate emissions and volatility distributions of semi- and intermediate-volatile organic compounds. The focus of the simulations is the summer season (May to July 2013), in order to quantify the sensitivity of the model in a period with relatively large photochemical activity. In addition to the model sensitivity, we validate the results with ad hoc OA measurements obtained from aerosol mass spectrometers at two monitoring sites. Unlike winter cases previously published, the comparison with experimental data showed limited sensitivity to total OA amount, with an estimated increase in OA concentrations limited to a few tenths of µg m⁻³, for both the primary and secondary components. We show that the lack of pronounced sensitivity is related to the effect of the new parametrizations on different emissions sectors. Furthermore, the minor sensitivity to the new parametrizations could be related to the greater partitioning of OA towards the gaseous phase in the summer period, thus reducing the organic fraction in the aerosol phase. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

13 pages, 1124 KiB

Open AccessArticle

The Relationship between Elemental Carbon and Volatile Organic Compounds in the Air of an Underground Metal Mine

by Andrzej Szczurek, Marcin Przybyła and Monika Maciejewska

Atmosphere 2022, 13(11), 1935; https://doi.org/10.3390/atmos13111935 - 21 Nov 2022

Cited by 1 | Viewed by 1461

Abstract

Elemental carbon (EC) content in air is considered a proxy for the diesel exhaust impact at workplaces. This paper examines the possibility of estimating EC content in mine air on the basis of measurements of volatile organic compounds (VOC). The measurement study was [...] Read more.

Elemental carbon (EC) content in air is considered a proxy for the diesel exhaust impact at workplaces. This paper examines the possibility of estimating EC content in mine air on the basis of measurements of volatile organic compounds (VOC). The measurement study was carried out in an underground metal mine. Gas chromatography with mass spectrometry (GC/MS) was applied for VOC determination, and thermal-optical analysis (TOA) with an FID detector was utilized for EC measurements. A correlation was found between the measurements of EC and total VOC (TVOC) as well as the content of individual hydrocarbons C12–C14 in the air of an extraction zone in the mine. A regression model was developed which predicts EC based on C12, C13, and C14, considered individually, and the remaining VOCs detected with GC/MS taken in total. The model was statistically significant (p = 0.053), and it offered an EC prediction error of RMSE = 4.60 µg/sample. The obtained result confirms the possibility of using VOC measurements for the preliminary estimation of EC concentrations in mine air. This approach is feasible given the availability of portable GC/MS and offers easy and fast measurements providing qualitative and quantitative information. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

19 pages, 13159 KiB

Open AccessEditor’s ChoiceArticle

Using Mobile Monitoring and Atmospheric Dispersion Modeling for Capturing High Spatial Air Pollutant Variability in Cities

by Grazia Fattoruso, Domenico Toscano, Antonella Cornelio, Saverio De Vito, Fabio Murena, Massimiliano Fabbricino and Girolamo Di Francia

Atmosphere 2022, 13(11), 1933; https://doi.org/10.3390/atmos13111933 - 20 Nov 2022

Cited by 2 | Viewed by 1683

Abstract

Air pollution is still one of the biggest environmental threats to human health on a global scale. In urban environments, exposure to air pollution is largely influenced by the activity patterns of the population as well as by the high spatial and temporal [...] Read more.

Air pollution is still one of the biggest environmental threats to human health on a global scale. In urban environments, exposure to air pollution is largely influenced by the activity patterns of the population as well as by the high spatial and temporal variability in air pollutant concentrations. Over the last years, several studies have attempted to better characterize the spatial variations in air pollutant concentrations within a city by deploying dense, fixed as well as mobile, low-cost sensor networks and more recently opportunistic sampling and by improving the spatial resolution of air quality models up to a few meters. The purpose of this work has been to investigate the use of properly designed mobile monitoring campaigns along the streets of an urban neighborhood to assess the capability of an operational air dispersion model as SIRANE at the district scale to capture the local variability of pollutant concentrations. To this end, an IoT ecosystem—MONICA (an Italian acronym for Cooperative Air Quality Monitoring), developed by ENEA, has been used for mobile measurements of CO and NO₂ concentration in the urban area of the City of Portici (Naples, Southern Italy). By comparing the mean concentrations of CO and NO₂ pollutants measured by MONICA devices and those simulated by SIRANE along the urban streets, the former appeared to exceed the simulated ones by a factor of 3 and 2 for CO and NO₂, respectively. Furthermore, for each pollutant, this factor is higher within the street canyons than in open roads. However, the mobile and simulated mean concentration profiles largely adapt, although the simulated profiles appear smoother than the mobile ones. These results can be explained by the uncertainty in the estimation of vehicle emissions in SIRANE as well as the different temporal resolution of measurements of MONICA able to capture local high concentrations. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

17 pages, 7001 KiB

Open AccessArticle

Analysis of the Spatial–Temporal Distribution Characteristics of NO₂ and Their Influencing Factors in the Yangtze River Delta Based on Sentinel-5P Satellite Data

by Xiaohui Guo, Zhen Zhang, Zongcai Cai, Leilei Wang, Zhengnan Gu, Yangyang Xu and Jinbiao Zhao

Atmosphere 2022, 13(11), 1923; https://doi.org/10.3390/atmos13111923 - 18 Nov 2022

Cited by 1 | Viewed by 1628

Abstract

The recent rapid economic development in the Yangtze River Delta (YRD) has led to atmospheric destruction; therefore, it is imperative to solve the issue of atmospheric environmental pollution to ensure stable long-term development. Based on the NO₂ column concentration observed by the [...] Read more.

The recent rapid economic development in the Yangtze River Delta (YRD) has led to atmospheric destruction; therefore, it is imperative to solve the issue of atmospheric environmental pollution to ensure stable long-term development. Based on the NO₂ column concentration observed by the TROPOMI (a tropospheric monitoring instrument) on the Sentinel-5P, the spatial–temporal distribution characteristics of the NO₂ column concentration in the YRD from 2019 to 2020 were analyzed using the Google Earth Engine (GEE) platform, and the Geographical Detector (Geodetector) model was used to determine the driving factors of the NO₂ column concentration. The results show that the correlation between the NO₂ column concentration and the ground-monitored NO₂ concentrations reached 70%. The annual variation trend of the NO₂ column concentration exhibited a ‘U’-shaped curve, with the characteristics of ‘high in winter and low in summer, with a transition between spring and autumn’. It exhibited obvious agglomeration characteristics in terms of the spatial distribution, with a high-value agglomeration in the central region of the YRD, followed by the northern region, and a low-value agglomeration in the southern region, with higher altitudes. The change in the NO₂ column concentration in the YRD was affected by both physical geographical factors and socio-economic factors; it is clear that the influence of socio-economic factors has increased. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

21 pages, 7155 KiB

Open AccessArticle

In-Depth Study of PM_2.5 and PM₁₀ Concentrations over a 12-Year Period and their Elemental Composition in the Lignite Center of Western Macedonia, Greece

by Vasilios Evagelopoulos, Paraskevi Begou and Stamatis Zoras

Atmosphere 2022, 13(11), 1900; https://doi.org/10.3390/atmos13111900 - 14 Nov 2022

Cited by 6 | Viewed by 1522

Abstract

Western Macedonia, located in North-western Greece, is largely dominated by lignite mining and lignite-fired power plants, which are a significant part of the country’s economy. However, the electricity generation and the related activities are among the greatest sources of air pollutants. In this [...] Read more.

Western Macedonia, located in North-western Greece, is largely dominated by lignite mining and lignite-fired power plants, which are a significant part of the country’s economy. However, the electricity generation and the related activities are among the greatest sources of air pollutants. In this study, we focus on the air quality of Western Macedonia based on measurements of Particulate Matter (PM_2.5 and PM₁₀) over a 12-year period (from 2010 to 2021) and a sampling of PM-bound trace elements over the course of 12 months (from December 2017 to November 2018). The analysis revealed an overall decrease of PM_2.5 and PM₁₀ concentrations over the study period. In general, the concentrations of PM exhibited seasonality patterns associated with the weather conditions and the local sources of air pollutants. These major sources of air pollution are the lignite mining processes, the emissions from the lignite-fired power plants, and the anthropogenic emissions from the biomass burning and heating systems. In addition, the analysis of the PM-bound trace elements revealed some differences; the elemental profiles of both PM_2.5 and PM₁₀ were quite similar, while the most abundant elements (Ca and Si) indicate that the main emission sources were related with the mining activities and the coal combustion. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

26 pages, 16136 KiB

Open AccessArticle

Assessment of Coarse, Fine, and Ultrafine Particles in S-Bahn Trains and Underground Stations in Stuttgart

by Abdul Samad, Kathryn Arango, Diego Alvarez Florez, Ioannis Chourdakis and Ulrich Vogt

Atmosphere 2022, 13(11), 1875; https://doi.org/10.3390/atmos13111875 - 10 Nov 2022

Cited by 1 | Viewed by 1763

Abstract

The Stuttgart S-Bahn network comprises six subway lines and is used by approximately 425,000 people on a daily basis. In previous studies in other cities, it was found that subways can be a source and collection point of particulate matter (PM), which is [...] Read more.

The Stuttgart S-Bahn network comprises six subway lines and is used by approximately 425,000 people on a daily basis. In previous studies in other cities, it was found that subways can be a source and collection point of particulate matter (PM), which is detrimental to human health. This study focused on making an initial assessment of the pollution situation inside the trains and on the underground platforms. Real-time measurements were performed with high time-resolution instruments inside the S-Bahn trains, two underground stations, and two outdoor stations in the Stuttgart subway network in November 2019. Firstly, the variation in concentration inside the train as it traveled through the tunnel was investigated, and it was recurrently observed that the pollutant concentration in the train increased while traveling through the tunnel and then decreased when nearing the tunnel exit. Secondly, the measurement location with the highest particulate matter concentrations was determined. The particulate matter concentrations on underground platforms were higher than those on the train and on the outdoor platforms. In addition, the dominant fraction of the particulate matter measured was in the range of ultrafine particles (UFP). Finally, the wind speed and wind direction data were analyzed in conjunction with specific locations along the platforms. From the wind measurement results, it was assumed that the combined airflows led to higher particle resuspension and particulate matter concentrations in these areas. In conclusion, it was determined that subway users were exposed to higher particle concentrations, particularly UFP (10–116 nm), while standing on underground platforms and when traveling through underground tunnels. It was found that the PNCs inside the train wagons as well as PM and BC mass concentrations increase when passing through the tunnel. Additionally, the average number concentration of UFPs on underground platforms was significantly higher than in other locations by factors of around 1.7 to 1.9 for UFPs and 1.6 to 2 for coarse and fine particles. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

20 pages, 5068 KiB

Open AccessArticle

Effects of Weather and Anthropogenic Precursors on Ground-Level Ozone Concentrations in Malaysian Cities

by Syaza Ezzati Baidrulhisham, Norazian Mohamed Noor, Zulkarnain Hassan, Andrei Victor Sandu, Petrica Vizureanu, Ahmad Zia Ul-Saufie, Mohd Remy Rozainy Mohd Arif Zainol, Aeslina Abdul Kadir and György Deák

Atmosphere 2022, 13(11), 1780; https://doi.org/10.3390/atmos13111780 - 28 Oct 2022

Cited by 8 | Viewed by 1806

Abstract

Ground-level ozone (O₃) is a significant source of air pollution, mainly in most urban areas across the globe. Ground-level O₃ is not emitted directly into the atmosphere. It results from photo-chemical reactions between precursors and is influenced by weather factors [...] Read more.

Ground-level ozone (O₃) is a significant source of air pollution, mainly in most urban areas across the globe. Ground-level O₃ is not emitted directly into the atmosphere. It results from photo-chemical reactions between precursors and is influenced by weather factors such as temperature. This study investigated the spatial and temporal analysis of ground-level ozone and analyzed the significant anthropogenic precursors and the weather parameters associated with ground-level ozone during daytime and nighttime at three cities in peninsular Malaysia, namely, Kuala Terengganu, Perai, and Seremban from 2016 to 2020. Secondary data were acquired from the Department of Environment (DOE), Malaysia, including hourly data of O₃ with trace gases and weather parameters. The secondary data were analyzed using temporal analysis such as descriptive statistics, box plot, and diurnal plot as well as spatial analysis such as contour plot and wind rose diagram. Spearman correlation was used to identify the association of O₃ with its precursors and weather parameters. The results show that a higher concentration of O₃ during the weekend due to “ozone weekend effects” was pronounced, however, a slightly significant effect was observed in Perai. The two monsoonal seasons in Malaysia had a minimal effect on the study areas except for Kuala Terengganu due to the geographical location. The diurnal pattern of O₃ concentration indicates bimodal peaks of O₃ precursors during the peak traffic hours in the morning and evening with the highest intensity of O₃ precursors detected in Perai. Spearman correlation analysis determined that the variations in O₃ concentrations during day and nighttime generally coincide with the influence of nitrogen oxides (NO) and temperature. Lower NO concentration will increase the amount of O₃ concentration and an increasing amount of O₃ concentration is influenced by the higher temperature of its surroundings. Two predictive models, i.e., linear (multiple linear regression) and nonlinear models (artificial neural network) were developed and evaluated to predict the next day and nighttime O₃ levels. ANN resulted in better prediction for all areas with better prediction identified for daytime O₃ levels. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

21 pages, 4808 KiB

Open AccessArticle

Exposure Assessment of Air Pollution in Lungs

by Akshoy Ranjan Paul, Anuj Jain and Suvash C. Saha

Atmosphere 2022, 13(11), 1767; https://doi.org/10.3390/atmos13111767 - 27 Oct 2022

Cited by 1 | Viewed by 1247

Abstract

In this article, a comprehensive literature survey on air pollution and its effects on the human respiratory system is carried out. Based on the knowledge gaps, a computational assessment is proposed to find the impact of air quality on respiratory suspended particulate matter [...] Read more.

In this article, a comprehensive literature survey on air pollution and its effects on the human respiratory system is carried out. Based on the knowledge gaps, a computational assessment is proposed to find the impact of air quality on respiratory suspended particulate matter (RSPM) deposition in the human airways. A realistic 3D geometric model of the human airway was constructed to study the airflow characteristics and RSPM (PM_2.5 and PM₁₀) transport and deposition in it for normal and moderate inhalation patterns (corresponding to natural breathing) of air having an unhealthy air quality index (AQI). The results identify inertial impact as the primary mechanism of particle deposition in the human airways. They also reveals the significant differences in the deposition patterns of PM_2.5 and PM₁₀ in the right and left bronchial airways. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

19 pages, 6033 KiB

Open AccessArticle

Atmospheric CO₂ Concentrations in Caves Protected as Nature Reserves and Related Gas Hazard

by Paolo Madonia, Marianna Cangemi, Giulia Casamento, Cipriano Di Maggio, Rosario Di Pietro, Marco Interlandi, Gianfranco Barraco, Roberto D’Aleo and Francesco Di Trapani

Atmosphere 2022, 13(11), 1760; https://doi.org/10.3390/atmos13111760 - 26 Oct 2022

Viewed by 2061

Abstract

Atmospheric CO₂ concentrations can reach high levels inside natural caves, representing a hazardous condition for both humans frequenting the underground environment and its safeguard due to the corrosion of speleothems induced by the acidification of atmospheric moisture. These issues are particularly critical [...] Read more.

Atmospheric CO₂ concentrations can reach high levels inside natural caves, representing a hazardous condition for both humans frequenting the underground environment and its safeguard due to the corrosion of speleothems induced by the acidification of atmospheric moisture. These issues are particularly critical for the eco-sustainable management of caves protected as nature reserves and undergoing touristic exploitation. In this paper we present the results of the C6 project, which was activated in 1999 for the monitoring of air quality inside three caves protected as nature reserves in Sicily (Italy). Near-real-time and spot measurements of air temperature and CO₂ concentration have been carried out since the year 2000, giving the opportunity of evaluating the gas hazard for visitors and its potential impact on the protected underground environments, as well as the influence of meteorological and hydrological conditions in driving carbon dioxide accumulations. The analysis of data acquired in the hypogeal atmosphere, and their comparison with analogous epigeal measures, indicates that carbon dioxide accumulation is controlled by a complex interaction among cave topography, meteorological dynamics, gaseous exchanges between groundwaters and the atmosphere, and human fruition. This last factor, under particular conditions, can surprisingly diminishing underground CO₂ concentrations. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

18 pages, 2266 KiB

Open AccessArticle

Advanced Oxidation Processes to Reduce Odor Emissions from Municipal Wastewater—Comprehensive Studies and Technological Concepts

by Marcin Dębowski, Joanna Kazimierowicz and Marcin Zieliński

Atmosphere 2022, 13(10), 1724; https://doi.org/10.3390/atmos13101724 - 20 Oct 2022

Cited by 3 | Viewed by 1814

Abstract

Municipal facilities can generate odors caused by substances such as fatty acids, organosulfur compounds, aldehydes, and inorganic gases, especially H₂S. Identifying an effective and cost-efficient solution to the problem is a priority for communities in areas at risk of exposure to [...] Read more.

Municipal facilities can generate odors caused by substances such as fatty acids, organosulfur compounds, aldehydes, and inorganic gases, especially H₂S. Identifying an effective and cost-efficient solution to the problem is a priority for communities in areas at risk of exposure to odors. The aim of this study was to evaluate the effect of advanced oxidation processes (AOPs) involving Fenton’s reagents (Fe²⁺/H₂O₂, Fe³⁺/H₂O₂) on wastewater profiles and their capacity to reduce putrescibility, H₂S emissions, and odor concentration in the air. The Fe²⁺/H₂O₂ system proved to be the most efficient in terms of inhibiting the process of redox conditions development, removing organic matter in the wastewater, inhibiting H₂S formation, and reducing odor emissions. H₂S generation in raw wastewater was triggered as early as on day 2 of anaerobic retention, with levels of 5.6 ppm to 64 ppm. After introduction of 0.1 g Fe²⁺/dm³ and 2.0 g H₂O₂/dm³, no H₂S was detected in the gas for 8 days. The odor concentration (OC) of raw wastewater (2980 ± 110 ou_e/m³) was reduced by 96.3 ± 1.9% to a level of 100 ± 15 ou_e/m³. The Fe²⁺/H₂O₂ system maintained its oxidizing capacity up until day 7, with OC reduction by 96.0 ± 0.8% to a level of 120 ± 10 ou_e/m³. On day 10, the OC showed a marked increase to a level 1310 ± 140 ou_e/m³. The conducted research has proven that Fenton-based AOP systems are a technologically and commercially viable method of deodorization of sewage facilities. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

19 pages, 7728 KiB

Open AccessArticle

Development and Application of the SmartAQ High-Resolution Air Quality and Source Apportionment Forecasting System for European Urban Areas

by Evangelia Siouti, Ksakousti Skyllakou, Ioannis Kioutsioukis, David Patoulias, George Fouskas and Spyros N. Pandis

Atmosphere 2022, 13(10), 1693; https://doi.org/10.3390/atmos13101693 - 16 Oct 2022

Cited by 5 | Viewed by 1847

Abstract

Air pollution forecasting systems are useful tools for the reduction in human health risks and the eventual improvement of atmospheric quality on regional or urban scales. The SmartAQ (Smart Air Quality) forecasting system combines state-of-the-art meteorological and chemical transport models to provide detailed [...] Read more.

Air pollution forecasting systems are useful tools for the reduction in human health risks and the eventual improvement of atmospheric quality on regional or urban scales. The SmartAQ (Smart Air Quality) forecasting system combines state-of-the-art meteorological and chemical transport models to provide detailed air pollutant concentration predictions at a resolution of 1 × 1 km² for the urban area of interest for the next few days. The Weather Research and Forecasting (WRF) mesoscale numerical weather prediction model is used to produce meteorological fields and the PMCAMx (Particulate Matter Comprehensive Air quality Model with extensions) chemical transport model for the simulation of air pollution. SmartAQ operates automatically in real time and provides, in its current configuration, a three-day forecast of the concentration of tens of gas-phase air pollutants (NO_x, SO₂, CO, O₃, volatile organic compounds, etc.), the complete aerosol size/composition distribution, and the source contributions for all primary and secondary pollutants. The system simulates the regional air quality in Europe at medium spatial resolution and can focus, using high resolution, on any urban area of the continent. The city of Patras in Greece is used for the first SmartAQ application, taking advantage of the available Patras’ dense low-cost sensor network for PM_2.5 (particles smaller than 2.5 μm) concentration measurements. Advantages of SmartAQ include (a) a high horizontal spatial resolution of 1 × 1 km² for the simulated urban area; (b) advanced treatment of the organic aerosol volatility and chemistry; (c) use of an updated emission inventory that includes not only the traditional sources (industry, transport, agriculture, etc.), but also biomass burning from domestic heating and cooking; (d) forecasting of not only the pollutant concentrations, but also of the sources contributions for each one of them using the Particulate matter Source Apportionment Technology (PSAT) algorithm. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

27 pages, 7005 KiB

Open AccessArticle

Routes Alternatives with Reduced Emissions: Large-Scale Statistical Analysis of Probe Vehicle Data in Lyon

by Alexandre Jayol, Delphine Lejri and Ludovic Leclercq

Atmosphere 2022, 13(10), 1681; https://doi.org/10.3390/atmos13101681 - 14 Oct 2022

Viewed by 1379

Abstract

Vehicle air pollution is a significant problem for health and climate change that can be solved by several approaches. The route is one of the many components to be considered. In this work, we propose a statistical analysis of a large FCD database [...] Read more.

Vehicle air pollution is a significant problem for health and climate change that can be solved by several approaches. The route is one of the many components to be considered. In this work, we propose a statistical analysis of a large FCD database in November 2017 in Lyon (France) in order to find alternative sustainable trips and evaluate potential emission reductions (CO₂, NOx, PM10). To this end, an innovative framework was built. First, we assessed vehicle speeds for each network section and the fifteen-minute period, when this information was reachable. Then, we used a regression random forest (RF) algorithm to fill in the missing data. This dynamical speed map allowed us to search for fewer pollutant trips, for the first ten days of November. By using COPERT emission factors (EFs) and the time-dependent Dijkstra algorithm, we successfully identified between 51% and 72% of alternative sustainable paths, depending on the engine technology and the pollutant. We investigated the influence of vehicle technology. In all cases, the number of alternative trips found tends to be the same as soon as the emission savings exceed 5%. Moreover, about 400 trips out of 11,000 have the potential to mitigate about 20% of emissions. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

13 pages, 3418 KiB

Open AccessArticle

Atmospheric Ultrafine Particulate Matter (PM_0.1)-Bound Carbon Composition in Bangkok, Thailand

by Worradorn Phairuang, Surapa Hongtieab, Panwadee Suwattiga, Masami Furuuchi and Mitsuhiko Hata

Atmosphere 2022, 13(10), 1676; https://doi.org/10.3390/atmos13101676 - 14 Oct 2022

Cited by 7 | Viewed by 2826

Abstract

Seasonal variations in atmospheric ultrafine particulate matter (PM_0.1) were monitored in Bangkok, Thailand, from 2016 to 2017. PM_0.1-bound organic carbon (OC) and elemental carbon (EC) were collected by a cascade air sampler that can collect PM_0.1 and were [...] Read more.

Seasonal variations in atmospheric ultrafine particulate matter (PM_0.1) were monitored in Bangkok, Thailand, from 2016 to 2017. PM_0.1-bound organic carbon (OC) and elemental carbon (EC) were collected by a cascade air sampler that can collect PM_0.1 and were analyzed by a Thermal-Optical carbon analyzer following the IMPROVE-TOR protocol. The annual average PM_0.1 in Bangkok was 14.5 ± 4.7 µg/m³, which is higher than in large Asian cities such as Shanghai and Hanoi. Biomass burning from neighboring areas was shown to increase the particle concentration. Apparent increases in carbon species such as OC and EC, and the OC/EC ratios in the wet and dry seasons were observed; the Char-EC/Soot-EC ratio revealed that the PM_0.1 in the Bangkok atmosphere was influenced mainly by vehicle exhausts, even though the influence of biomass burning was greater during the dry season. The effective carbon ratio (ECR) shows that Bangkok’s carbonaceous aerosol is light-absorbing and -scattering. The higher SOC/OC in the dry season indicates the high level of secondary sources forming smaller particles from the combustion sources in Bangkok, increasing light scattering during these periods, and contributing to climate and air quality. The findings of this work are of great importance to air pollutant control policies in urban areas. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Graphical abstract

20 pages, 4763 KiB

Open AccessArticle

Comparison of Particle Sizers and Counters with Soot-like, Salt, and Silver Particles

by Barouch Giechaskiel and Anastasios Melas

Atmosphere 2022, 13(10), 1675; https://doi.org/10.3390/atmos13101675 - 13 Oct 2022

Cited by 5 | Viewed by 2077

Abstract

Vehicle emission regulations in Europe and many Asian countries include a particle number limit. The number concentration is measured, typically, with condensation particle counters (CPCs). For research purposes, the size distributions provide useful information. Scanning mobility particle sizers (SMPSs) accurately provide the size [...] Read more.

Vehicle emission regulations in Europe and many Asian countries include a particle number limit. The number concentration is measured, typically, with condensation particle counters (CPCs). For research purposes, the size distributions provide useful information. Scanning mobility particle sizers (SMPSs) accurately provide the size distribution but are not suitable for transient aerosol. Engine (fast) exhaust particle sizers (EEPSs) cover this gap, but with less accuracy. Fast size distribution instruments are commonly used in the research and development of engines. In the last few years, instrument algorithms have been improved, but studies assessing the improvements are limited, in particular in their lower size range, around 10–20 nm, and for soot-like aerosol. In this paper, we compared the three instruments using salt, silver, diffusion flame soot (CAST), and spark discharge graphite particles. Moreover, vehicle exhaust number concentration measurements with EEPSs over a seven-year period were presented. In terms of particle concentration, EEPS overestimated, on average, 25% compared to CPC, in agreement with previous studies. Its accuracy for mean particle size determination was better than 5 nm compared to SMPS. The agreement between the instruments was satisfactory but the uncertainty increased at low concentrations and larger particle sizes, showing that there is still room for further improvements. Experimental challenges, such as low concentration levels of modern vehicles, losses in the diluters, use of photometric mode by the CPCs, and the material impact, are also discussed. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

16 pages, 7947 KiB

Open AccessArticle

Analysis of the Radon Concentration in Selected Rooms of Buildings in Poznan County

by Joanna Aleksandra Kubiak and Małgorzata Basińska

Atmosphere 2022, 13(10), 1664; https://doi.org/10.3390/atmos13101664 - 12 Oct 2022

Cited by 4 | Viewed by 1162

Abstract

This article presents the results of the research carried out in selected rooms of buildings located in Poznan. According to the measurements, the highest average radon concentration in the buildings in Poznan County was at the level of 130 ± 32 Bqm⁻³ [...] Read more.

This article presents the results of the research carried out in selected rooms of buildings located in Poznan. According to the measurements, the highest average radon concentration in the buildings in Poznan County was at the level of 130 ± 32 Bqm⁻³. The lowest mean concentration was 31 ± 8 Bqm⁻³ and was measured in a seven-year-old educational institution. Based on the performed measurements, non-uniformity of the correlation between the radon concentration and temperature and humidity was observed. For all the measurement sites where volatile organic compounds were counted, a positive correlation with radon was observed (r_xy = 0.31, p < 0.001). A negative correlation was obtained (r_xy = −0.15, p < 0.001) between the concentration of radon and the concentration of carbon dioxide. Based on the analysis of the research conducted, it was found that the concentration of radon in a given room depends on many factors, such as temperature, humidity, and room usage profile. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

35 pages, 1750 KiB

Open AccessEditor’s ChoiceArticle

Air Pollution Dispersion Modelling in Urban Environment Using CFD: A Systematic Review

by Mariya Pantusheva, Radostin Mitkov, Petar O. Hristov and Dessislava Petrova-Antonova

Atmosphere 2022, 13(10), 1640; https://doi.org/10.3390/atmos13101640 - 09 Oct 2022

Cited by 16 | Viewed by 5631

Abstract

Air pollution is a global problem, which needs to be understood and controlled to ensure a healthy environment and inform sustainable development. Urban areas have been established as one of the main contributors to air pollution, and, as such, urban air quality is [...] Read more.

Air pollution is a global problem, which needs to be understood and controlled to ensure a healthy environment and inform sustainable development. Urban areas have been established as one of the main contributors to air pollution, and, as such, urban air quality is the subject of an increasing volume of research. One of the principal means of studying air pollution dispersion is to use computational fluid dynamics (CFD) models. Subject to careful verification and validation, these models allow for analysts to predict air flow and pollution concentration for various urban morphologies under different environmental conditions. This article presents a detailed review of the use of CFD to model air pollution dispersion in an urban environment over the last decade. The review extracts and summarises information from nearly 90 pieces of published research, categorising it according to over 190 modelling features, which are thematically systemised into 7 groups. The findings from across the field are critically compared to available urban air pollution modelling guidelines and standards. Among the various quantitative trends and statistics from the review, two key findings stand out. The first is that, despite the existence of best practice guidelines for pollution dispersion modelling, anywhere between 12% and 34% of the papers do not specify one or more aspects of the utilised models, which are required to reproduce the study. The second is that none of the articles perform verification and validation according to accepted standards. The results of this review can, therefore, be used by practitioners in the field of pollution dispersion modelling to understand the general trends in current research and to identify open problems to be addressed in the future. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

13 pages, 1697 KiB

Open AccessArticle

Analysis of the Air Quality of a District Heating System with a Biomass Plant

by Nicoletta Lotrecchiano and Daniele Sofia

Atmosphere 2022, 13(10), 1636; https://doi.org/10.3390/atmos13101636 - 08 Oct 2022

Cited by 1 | Viewed by 1273

Abstract

Heating is one of the major causes of pollution in urban areas, producing high concentrations of aero-dispersed particulate matter (PM) that can cause serious damage to the respiratory system. A possible solution is the implementation of a district heating system, which would decrease [...] Read more.

Heating is one of the major causes of pollution in urban areas, producing high concentrations of aero-dispersed particulate matter (PM) that can cause serious damage to the respiratory system. A possible solution is the implementation of a district heating system, which would decrease the presence of conventional heating systems, reducing PM emissions. The case study considered involves the municipality of Serra San Bruno (Italy), located near a biomass plant, which could play the role of a thermal conversion plant for a possible district heating network. To determine the heating incidence on pollution, the large users in the area were identified. The large users’ consumption estimation was carried out, obtaining the thermal energy requirement linked to the residential, which is about 3.5 times that of all the large users. Through air quality measuring devices, PM concentrations were measured for the winter and the summer period. PM emissions were then estimated using emission factors and the decreases in PM concentrations were calculated if part of the domestic users were converted to district heating, compatibly with the possibility of supplying energy to the biomass power plant. The replacement of conventional plants in favor of a district heating network has a positive impact on PM pollution. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

16 pages, 1796 KiB

Open AccessArticle

Impact of Aviation Emissions and its Changes Due to the COVID-19 Pandemic on Air Quality in South Korea

by Yoonbae Chung and Young Sunwoo

Atmosphere 2022, 13(10), 1553; https://doi.org/10.3390/atmos13101553 - 23 Sep 2022

Cited by 2 | Viewed by 1708

Abstract

This study analyzed the impact of aviation emissions based on the 2017 CAPSS (Clean Air Policy Support System) data. We focused on major airports in South Korea and examined the concentration of NO₂ and PM_2.5 by the WRF-SMOKE-CMAQ modeling system. Furthermore, [...] Read more.

This study analyzed the impact of aviation emissions based on the 2017 CAPSS (Clean Air Policy Support System) data. We focused on major airports in South Korea and examined the concentration of NO₂ and PM_2.5 by the WRF-SMOKE-CMAQ modeling system. Furthermore, the number of flights in Korea greatly declined in response to the COVID-19 pandemic. To assess the impact of COVID-19 on aviation emissions, time resolution data were newly derived and air pollutant emissions for 2020 were calculated. Additional BAU (Business as Usual) emissions were calculated as well for comparison. Among airports in Korea, RKSI (Incheon International Airport) had the greatest impact on air quality in nearby areas. Changes in emissions due to COVID-19 showed a large deviation by airports for domestic emissions while international emissions had a consistent decrease. The reduced emissions had the strongest impact on air quality in the RKSI area as well. By analyzing aviation emissions due to COVID-19, this study confirmed the notable relationship with the pandemic and air quality. We conclusively recommend that policymakers and industry take note of trends in aviation emissions while establishing future atmospheric environment plans. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

22 pages, 5939 KiB

Open AccessArticle

Simultaneous Monitoring of Outdoor PAHs and Particles in a French Peri-Urban Site during COVID Restrictions and the Winter Saharan Dust Event

by Farhan Ramadzan Nursanto, Joana Vaz-Ramos, Olivier Delhomme, Sylvie Bégin-Colin and Stéphane Le Calvé

Atmosphere 2022, 13(9), 1435; https://doi.org/10.3390/atmos13091435 - 05 Sep 2022

Cited by 2 | Viewed by 1533

Abstract

The presence of polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM) in air is known to provoke deleterious effects on human health. This work focused on the monitoring of PM and PAHs in the air over four weeks in a peri-urban site in [...] Read more.

The presence of polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM) in air is known to provoke deleterious effects on human health. This work focused on the monitoring of PM and PAHs in the air over four weeks in a peri-urban site in Strasbourg (France), using a three-stage cascade impactor and a particle analyser allowing PM₁, PM_2.5 and PM₁₀ discrimination. Meteorological conditions were monitored to study their influence on the pollutant levels. The average PM₁₀ concentration of the cascade impactor and particle analyser varied from 11.8 to 80.2 µg/m³ and 10.6 to 220.2 µg/m³, respectively. The PAH total concentration ranged in 1.1–7.6 ng/m³ and a predominance of 5- and 6-ring PAHs was observed. PAHs were also more abundant in finer particles (PM₁). Specifically, identified PAHs are traffic tracers suggesting that vehicular emission was one of its main sources. Two pollution episodes, associated with either a Saharan dust wind episode or traffic pollution, were observed, and led to PM₁₀ and PM_2.5 surpassing the daily limit values established by the European Union despite the traffic limitations according to the COVID restrictions. The total PAH concentrations were the highest during these periods suggesting PAHs might be bound to and transported via dust particles. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

12 pages, 2529 KiB

Open AccessArticle

The Reaction of HO₂ and CH₃O₂: CH₃OOH Formed from the Singlet Electronic State Surface

by Thanh Lam Nguyen and John F. Stanton

Atmosphere 2022, 13(9), 1397; https://doi.org/10.3390/atmos13091397 - 30 Aug 2022

Viewed by 1267

Abstract

High-level coupled-cluster calculations in combination with two-dimensional master equation simulations were used to study the HO₂ + CH₃O₂ reaction, which plays an important role in the oxidation of methane and hydrocarbons in the Earth’s atmosphere and low-temperature combustion. The [...] Read more.

High-level coupled-cluster calculations in combination with two-dimensional master equation simulations were used to study the HO₂ + CH₃O₂ reaction, which plays an important role in the oxidation of methane and hydrocarbons in the Earth’s atmosphere and low-temperature combustion. The main reaction pathways taking place on the lowest-lying triplet and singlet potential energy surfaces (PES) were characterized. Interestingly, methyl hydroperoxide (CH₃OOH), the sole product, could be produced from both the triplet and singlet PESs, with a ratio of roughly 9:1. Formaldehyde is not made as a primary product, but can be formed via secondary chemistry. The formation of methyl tetraoxide (MTO) from the singlet PES is unimportant. The calculated reaction rate coefficients were found to be practically pressure-independent for p ≤ 760 Torr and can be given by

k (T) = 2.75 \times 10^{- 13} \times e^{+ 1.75 k c a l m o l^{- 1} / R T}

(in cm³/s), an expression useful for kinetics modeling over the range T = 200–800 K. The rate constant has a slight negative Arrhenius energy dependence of about −1.75 kcal mol^–1, falling about a factor of 30 from 200 K to 800 K. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

16 pages, 4035 KiB

Open AccessArticle

Reconstruction of Daily Courses of SO₄²⁻, NO₃⁻, NH₄⁺ Concentrations in Precipitation from Cumulative Samples

by Iva Hůnová, Marek Brabec, Marek Malý and Hana Škáchová

Atmosphere 2022, 13(7), 1049; https://doi.org/10.3390/atmos13071049 - 30 Jun 2022

Cited by 2 | Viewed by 1446

Abstract

It is important to study precipitation chemistry to comprehend both atmospheric and environmental processes. The aim of this study was the reconstruction of daily concentration patterns of major ions in precipitation from samples exposed for longer and differing time periods. We explored sulphates [...] Read more.

It is important to study precipitation chemistry to comprehend both atmospheric and environmental processes. The aim of this study was the reconstruction of daily concentration patterns of major ions in precipitation from samples exposed for longer and differing time periods. We explored sulphates (SO₄²⁻), nitrates (NO₃⁻) and ammonium (NH₄⁺) ions measured in precipitation within a nation-wide atmospheric deposition monitoring network in the Czech Republic during 1980–2020. We visualised the long-term trends at selected individual years for four stations, Praha 4-Libuš (LIB), Svratouch (SVR), Rudolice v Horách (RUD) and Souš (SOU), differing in geographical location and reflecting different environments. We found anticipated time trends reflecting the emission patterns of the precursors, i.e., sharp decreases in SO₄²⁻, milder decreases in NO₃⁻ and steady states in NH₄⁺ concentrations in precipitation. Statistically significant decreasing time trends in SO₄²⁻ and NO₃⁻ concentrations in precipitation between 1990 and 2015 were revealed for the LIB and SVR sites. Spring maxima in April were found for all major ions at the LIB site and for NO₃⁻ for the SVR site, for both past and current samples, whereas no distinct seasonal behaviour was recorded for NH₄⁺ at the RUD and SO₄²⁻ at the SVR sites. By applying Bayesian modelling and the Integrated Nested Laplace Approximation approach, we were able to reconstruct the daily patterns of SO₄²⁻, NO₃⁻ and NH₄⁺ concentrations in precipitation, which might be further utilised for a wide range of tasks, including comparison of magnitudes and shapes between stations, grouping the decomposed daily data into the ecologically motivated time periods, as well as for logical checks of sampling and measurement reliability. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

14 pages, 2137 KiB

Open AccessArticle

PM_2.5 Pollution Levels and Chemical Components at Teahouses along the Poon Hill Trek in Nepal

by James D. Johnston, John D. Beard, M. Lelinneth B. Novilla, Frank X. Weber and Ryan T. Chartier

Atmosphere 2022, 13(7), 1018; https://doi.org/10.3390/atmos13071018 - 24 Jun 2022

Cited by 1 | Viewed by 1704

Abstract

Unhealthy levels of fine particulate matter (PM_2.5) from the local burning of solid fuels, and from regional transport of pollutants, remain a major public health problem in the Himalayan foothill villages in Nepal. Teahouses (i.e., mountain lodges) along popular hiking trails [...] Read more.

Unhealthy levels of fine particulate matter (PM_2.5) from the local burning of solid fuels, and from regional transport of pollutants, remain a major public health problem in the Himalayan foothill villages in Nepal. Teahouses (i.e., mountain lodges) along popular hiking trails in the lower Himalayas commonly use wood as the primary energy source for heating; however, little is known about teahouse air quality. The purpose of this study was to characterize the levels and chemical constituents of indoor and ambient PM_2.5 at three villages along the Poon Hill circuit trek in the Annapurna Conservation Area in Nepal. A convenience sample of five PM_2.5 measurements was collected with portable MicroPEM V.3.2A exposure monitors. Filters were analyzed for black and brown carbon using integrating sphere optical transmittance and 33 elemental constituents using energy-dispersive X-ray fluorescence. Median indoor PM_2.5 over the sampling period was 41.3 µg/m³, whereas median ambient PM_2.5 over the sampling period was 34.7 µg/m³. Chemical species associated with wood smoke, such as potassium (GM = 0.88 µg/m³), predominated. High indoor and ambient PM_2.5 levels may pose a significant occupational health risk to teahouse workers, who may experience chronic exposures during trekking seasons. Our findings warrant additional research to characterize teahouse air pollution exposures more fully and to evaluate intervention measures. Full article

(This article belongs to the Special Issue Feature Papers in Air Quality)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Feature Papers in Air Quality

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (39 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI