Editorial

4 pages, 163 KiB

Open AccessEditorial

Advances in Air Quality Monitoring and Assessment

by Thomas Maggos

Appl. Sci. 2021, 11(13), 5817; https://doi.org/10.3390/app11135817 - 23 Jun 2021

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Air quality monitoring is a long-term assessment of pollutant levels that helps to assess the extent of pollution and provide information about air quality trends [...] Full article

(This article belongs to the Special Issue Advances in Air Quality Monitoring and Assessment)

Research

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8 pages, 1052 KiB

Open AccessCommunication

Towards Improving Transparency of Count Data Regression Models for Health Impacts of Air Pollution

by John F. Joseph, Chad Furl, Hatim O. Sharif, Thankam Sunil and Charles G. Macias

Appl. Sci. 2021, 11(8), 3375; https://doi.org/10.3390/app11083375 - 09 Apr 2021

Cited by 1 | Viewed by 1288

Abstract

In studies on the health impacts of air pollution, regression analysis continues to advance far beyond classical linear regression, which many scientists may have become familiar with in an introductory statistics course. With each new level of complexity, regression analysis may become less [...] Read more.

In studies on the health impacts of air pollution, regression analysis continues to advance far beyond classical linear regression, which many scientists may have become familiar with in an introductory statistics course. With each new level of complexity, regression analysis may become less transparent, even to the analyst working with the data. This may be especially true in count data regression models, where the response variable (typically given the symbol y) is count data (i.e., takes on values of 0, 1, 2, …). In such models, the normal distribution (the familiar bell-shaped curve) for the residuals (i.e., the differences between the observed values and the values predicted by the regression model) no longer applies. Unless care is taken to correctly specify just how those residuals are distributed, the tendency to accept untrue hypotheses may be greatly increased. The aim of this paper is to present a simple histogram of predicted and observed count values (POCH), which, while rarely found in the environmental literature but presented in authoritative statistical texts, can dramatically reduce the risk of accepting untrue hypotheses. POCH can also increase the transparency of count data regression models to analysts themselves and to the scientific community in general. Full article

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12 pages, 4274 KiB

Open AccessArticle

Study on the Ozone Gas Sensing Properties of rf-Sputtered Al-Doped NiO Films

by Athanasios Paralikis, Emmaouil Gagaoudakis, Viktoras Kampitakis, Elias Aperathitis, George Kiriakidis and Vassilios Binas

Appl. Sci. 2021, 11(7), 3104; https://doi.org/10.3390/app11073104 - 31 Mar 2021

Cited by 13 | Viewed by 1625

Abstract

Al-doped NiO (NiO:Al) has attracted the interest of researchers due to its excellent optical and electrical properties. In this work, NiO:Al films were deposited on glass substrates by the radio frequencies (rf) sputtering technique at room temperature and they were tested against ozone [...] Read more.

Al-doped NiO (NiO:Al) has attracted the interest of researchers due to its excellent optical and electrical properties. In this work, NiO:Al films were deposited on glass substrates by the radio frequencies (rf) sputtering technique at room temperature and they were tested against ozone gas. The Oxygen content in (Ar-O₂) plasma was varied from 2% to 4% in order to examine its effect on the gas sensing performance of the films. The thickness of the films was between 160.3 nm and 167.5 nm, while the Al content was found to be between 5.3 at% and 6.7 at%, depending on the oxygen content in plasma. It was found that NiO:Al films grown with 4% O₂ in plasma were able to detect 60 ppb of ozone with a sensitivity of 3.18% at room temperature, while the detection limit was further decreased to 10 ppb, with a sensitivity of 2.54%, at 80 °C, which was the optimum operating temperature for these films. In addition, the films prepared in 4% O₂ in plasma had lower response and recovery time compared to those grown with lower O₂ content in plasma. Finally, the role of the operating temperature on the gas sensing properties of the NiO:Al films was investigated. Full article

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16 pages, 942 KiB

Open AccessArticle

Contamination and Potential Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) and Heavy Metals in House Settled Dust Collected from Residences of Young Children

by A. Stamatelopoulou, M. Dasopoulou, K. Bairachtari, S. Karavoltsos, A. Sakellari and T. Maggos

Appl. Sci. 2021, 11(4), 1479; https://doi.org/10.3390/app11041479 - 06 Feb 2021

Cited by 17 | Viewed by 2157

Abstract

House settled dust (HSD) contains various hazardous materials, including polycyclic aromatic hydrocarbons (PAHs) and metals. Exposure to toxicants contained in HSD is of paramount concern especially in the case of young children, due to their particular behavioral characteristics. In this context, extracts of [...] Read more.

House settled dust (HSD) contains various hazardous materials, including polycyclic aromatic hydrocarbons (PAHs) and metals. Exposure to toxicants contained in HSD is of paramount concern especially in the case of young children, due to their particular behavioral characteristics. In this context, extracts of sieved vacuum cleaner dust from 20 residences with young children were examined for the presence of PAHs and trace metals, in Athens, Greece. The results indicated that PAHs and metals were ubiquitous in the studied residences. The calculated enrichment factors (EF) of trace metals indicated that Cu, Se, Zn, Hg, Cd, and Pb were mainly of anthropogenic. According to the PCA analysis, the main sources of household dust were: smoking inside the houses, combustion processes, resuspension of soil dust, and vehicle traffic. In general, the cancer risk due to PAHs exposure was found lower than the threshold value. The ingestion of house dust was the most important route of exposure to metals. The dose of almost all elements for the children was found 1–2 orders of magnitude lower than the corresponding reference values. Both the carcinogenic and noncarcinogenic risks of exposure were within the safety limits. Full article

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18 pages, 3509 KiB

Open AccessArticle

Emissions Reduction of Greenhouse Gases, Ozone Precursors, Aerosols and Acidifying Gases from Road Transportation during the COVID-19 Lockdown in Colombia

by Yiniva Camargo-Caicedo, Laura C. Mantilla-Romo and Tomás R. Bolaño-Ortiz

Appl. Sci. 2021, 11(4), 1458; https://doi.org/10.3390/app11041458 - 05 Feb 2021

Cited by 17 | Viewed by 3801

Abstract

The aim of this work was to analyze the changes in the emissions from the transport sector during the COVID-19 lockdown in Colombia. We compared estimated emissions from road transportation of four groups of pollutants, namely, greenhouse gases (CO₂, CH₄ [...] Read more.

The aim of this work was to analyze the changes in the emissions from the transport sector during the COVID-19 lockdown in Colombia. We compared estimated emissions from road transportation of four groups of pollutants, namely, greenhouse gases (CO₂, CH₄, N₂O), ozone precursor gases (CO, NMVOC, NOx), aerosols (BC, PM_2.5, PM₁₀), and acidifying gases (NH₃, SO₂), during the first half of 2020 with values obtained in the same period of 2018. The estimate of emissions from road transportation was determined using a standardized methodology consistent with the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories and the European Environment Agency/European Monitoring and Evaluation Program. We found a substantial reduction in GHG emissions for CH₄, N₂O, and CO₂ by 17%, 21%, and 28%, respectively. The ozone precursors CO and NMVOC presented a decrease of 21% and 22%, respectively, while NOx emissions were reduced up to 15% for the study period. In addition, BC decreased 15%, and there was a reduction of 17% for both PM₁₀ and PM_2.5 emissions. Finally, acidifying gases presented negative variations of 19% for SO₂ and 23% for NH₃ emissions. Furthermore, these results were consistent with the Ozone Monitoring Instrument (OMI) satellite observations and measurements at air quality stations. Our results suggest that the largest decreases were due to the reduction in the burning of gasoline and diesel oil from the transport sector during the COVID-19 lockdown. These results can serve decision makers in adopting strategies to improve air quality related to the analyzed sector. Full article

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19 pages, 44688 KiB

Open AccessArticle

Evaluating the Real-World NOx Emission from a China VI Heavy-Duty Diesel Vehicle

by Peng Li and Lin Lü

Appl. Sci. 2021, 11(3), 1335; https://doi.org/10.3390/app11031335 - 02 Feb 2021

Cited by 9 | Viewed by 2274

Abstract

The manufacturers of China VI heavy-duty vehicles were required to conduct in-service conformity (ISC) tests by using a portable emissions measurement system (PEMS). The moving averaging window (MAW) method was used to evaluate the NOx emission required by the China VI emission standard. [...] Read more.

The manufacturers of China VI heavy-duty vehicles were required to conduct in-service conformity (ISC) tests by using a portable emissions measurement system (PEMS). The moving averaging window (MAW) method was used to evaluate the NOx emission required by the China VI emission standard. This paper presented the results of four PEMS tests of a China VI (step B) N3 category vehicle. Our analyses revealed that the real NOx emission of the test route was much higher than the result evaluated by the MAW method. We also found the data produced during the urban section of a PEMS test was completely excluded from the evaluation based on the current required boundary conditions. Therefore, in order to ensure the objectivity of the evaluation, this paper proposed three different evaluation methods. Method 1 merely set the power threshold as 10% for valid MAWs; Method 2 reclassified the MAWs into “Urban MAWs”, “Rural MAWs” and “Motorway MAWs” according to the vehicle speed. Method 3 reclassified the MAWs into “Hot MAWs” and “Cold MAWs” according to engine coolant temperature. The NOx emission evaluation results for Method 1 were not satisfactory, but those for Method 2 and Method 3 were close to the real NOx emission, the errors were all within ±10%. Full article

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19 pages, 8588 KiB

Open AccessArticle

Diurnal, Temporal and Spatial Variations of Main Air Pollutants Before and during Emergency Lockdown in the City of Novi Sad (Serbia)

by Miloš Davidović, Sonja Dmitrašinović, Maja Jovanović, Jelena Radonić and Milena Jovašević-Stojanović

Appl. Sci. 2021, 11(3), 1212; https://doi.org/10.3390/app11031212 - 28 Jan 2021

Cited by 15 | Viewed by 2123

Abstract

Changes in air pollution in the region of the city of Novi Sad due to the COVID-19 induced state of emergency were evaluated while using data from permanently operating air quality monitoring stations belonging to the national, regional, and local networks, as well [...] Read more.

Changes in air pollution in the region of the city of Novi Sad due to the COVID-19 induced state of emergency were evaluated while using data from permanently operating air quality monitoring stations belonging to the national, regional, and local networks, as well as ad hoc deployed low-cost particulate matter (PM) sensors. The low-cost sensors were collocated with reference gravimetric pumps. The starting idea for this research was to determine if and to what extent a massive change of anthropogenic activities introduced by lockdown could be observed in main air pollutants levels. An analysis of the data showed that fine and coarse particulate matter, as well as SO₂ levels, did not change noticeably, compared to the pre-lockdown period. Isolated larger peaks in PM pollution were traced back to the Aralkum Desert episode. The reduced movement of vehicles and reduced industrial and construction activities during the lockdown in Novi Sad led to a reduction and a more uniform profile of the PM_2.5 levels during the period between morning and afternoon air pollution peak, approximately during typical working hours. Daily profiles of NO₂, NO, and NO_X during the state of emergency proved lower levels during most hours of the day, due to restrictions on vehicular movement. CO during the state of the emergency mainly exhibited a lower level during night. Pollutants having transportation-dominated source profiles exhibited a decrease in level, while pollutants with domestic heating source profiles mostly exhibited a constant level. Considering local sources in Novi Sad, slight to moderate air quality improvement was observed after the lockdown as compared with days before. Furthermore, PM low-cost sensors’ usefulness in air quality assessment was confirmed, as they increase spatial resolution, but it is necessary to calibrate them at the deployment location. Full article

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17 pages, 7799 KiB

Open AccessArticle

Finding Optimal Stations Using Euclidean Distance and Adjustable Surrounding Sphere

by Athita Onuean, Hanmin Jung and Krisana Chinnasarn

Appl. Sci. 2021, 11(2), 848; https://doi.org/10.3390/app11020848 - 18 Jan 2021

Cited by 5 | Viewed by 1993

Abstract

Air quality monitoring network (AQMN) plays an important role in air pollution management. However, setting up an initial network in a city often lacks necessary information such as historical pollution and geographical data, which makes it challenging to establish an effective network. Meanwhile, [...] Read more.

Air quality monitoring network (AQMN) plays an important role in air pollution management. However, setting up an initial network in a city often lacks necessary information such as historical pollution and geographical data, which makes it challenging to establish an effective network. Meanwhile, cities with an existing one do not adequately represent spatial coverage of air pollution issues or face rapid urbanization where additional stations are needed. To resolve the two cases, we propose four methods for finding stations and constructing a network using Euclidean distance and the k-nearest neighbor algorithm, consisting of Euclidean Distance (ED), Fixed Surrounding Sphere (FSS), Euclidean Distance + Fixed Surrounding Sphere (ED + FSS), and Euclidean Distance + Adjustable Surrounding Sphere (ED + ASS). We introduce and apply a coverage percentage and weighted coverage degree for evaluating the results from our proposed methods. Our experiment result shows that ED + ASS is better than other methods for finding stations to enhance spatial coverage. In the case of setting up the initial networks, coverage percentages are improved up to 22%, 37%, and 56% compared with the existing network, and adding a station in the existing one improved up by 34%, 130%, and 39%, in Sejong, Bonn, and Bangkok cities, respectively. Our method depicts acceptable results and will be implemented as a guide for establishing a new network and can be a tool for improving spatial coverage of the existing network for future expansions in air monitoring. Full article

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24 pages, 3643 KiB

Open AccessFeature PaperArticle

Atmospheric Concentrations and Health Implications of PAHs, PCBs and PCDD/Fs in the Vicinity of a Heavily Industrialized Site in Greece

by Konstantinos G. Koukoulakis, Panagiotis George Kanellopoulos, Eirini Chrysochou, Danae Costopoulou, Irene Vassiliadou, Leondios Leondiadis and Evangelos Bakeas

Appl. Sci. 2020, 10(24), 9023; https://doi.org/10.3390/app10249023 - 17 Dec 2020

Cited by 9 | Viewed by 2463

Abstract

Background: Thriassion Plain is considered the most industrialized area in Greece and thus a place where emissions of pollutants are expected to be elevated, leading to the degradation of air quality. Methods: Simultaneous determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), and [...] Read more.

Background: Thriassion Plain is considered the most industrialized area in Greece and thus a place where emissions of pollutants are expected to be elevated, leading to the degradation of air quality. Methods: Simultaneous determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs) was performed in PM10 samples. SPSS statistical package was employed for statistical analysis and source apportionment purposes. Cancer risk was estimated from total persistent organic pollutants’ (POPs) dataset according to the available literature. Results: POPs concentrations in particulate matter were measured in similar levels compared to other studies in Greece and worldwide, with mean concentrations of ΣPAHs, ΣPCDD/Fs, dioxin like PCBs, and indicator PCBs being 7.07 ng m⁻³, 479 fg m⁻³, 1634 fg m⁻³, and 18.1 pg m⁻³, respectively. Seasonal variations were observed only for PAHS with higher concentrations during cold period. MDRs, D/F ratios, and principal component analysis (PCA) highlighted combustions as the main source of POPs’ emissions. Estimation of particles’ carcinogenic and mutagenic potential indicates the increased toxicity of PM10 during cold periods, and cancer risk assessment concludes that 3 to 4 people out of 100,000 may suffer from cancer due to POPs’ inhalation. Conclusions: Increased cancer risk for citizens leads to the necessity of chronic POPs’ monitoring in Thriassion Plain, and such strategies have to be a priority for Greek environmental authorities. Full article

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17 pages, 6159 KiB

Open AccessArticle

Pollution Characteristics of Particulate Matter (PM_2.5 and PM₁₀) and Constituent Carbonaceous Aerosols in a South Asian Future Megacity

by Afifa Aslam, Muhammad Ibrahim, Imran Shahid, Abid Mahmood, Muhammad Kashif Irshad, Muhammad Yamin, Ghazala, Muhammad Tariq and Redmond R. Shamshiri

Appl. Sci. 2020, 10(24), 8864; https://doi.org/10.3390/app10248864 - 11 Dec 2020

Cited by 17 | Viewed by 4091

Abstract

The future megacity of Faisalabad is of prime interest when considering environmental health because of its bulky population and abundant industrial and anthropogenic sources of coarse particles (PM₁₀) and fine airborne particulate matter (PM_2.5). The current study was aimed [...] Read more.

The future megacity of Faisalabad is of prime interest when considering environmental health because of its bulky population and abundant industrial and anthropogenic sources of coarse particles (PM₁₀) and fine airborne particulate matter (PM_2.5). The current study was aimed to investigate the concentration level of PM_2.5 and PM₁₀, also the characterization of carbonaceous aerosols including organic carbon (OC), elemental carbon (EC) and total carbon (TC) in PM_2.5 and PM₁₀ samples collected from five different sectors (residential, health, commercial, industrial, and vehicular zone). The data presented here are the first of their kind in this sprawling city having industries and agricultural activities side by side. Results of the study revealed that the mass concentration of PM_2.5 and PM₁₀ is at an elevated level throughout Faisalabad, with ambient PM_2.5 and PM₁₀ points that constantly exceeded the 24-h standards of US-EPA, and National Environment Quality Standards (NEQS) which poses harmful effects on the quality of air and health. The total carbon concentration varied between 21.33 and 206.84 μg/m³, and 26.08 and 211.15 μg/m³ with an average of 119.16 ± 64.91 μg/m³ and 124.71 ± 64.38 μg/m³ for PM_2.5 in summer and winter seasons, respectively. For PM₁₀, the concentration of TC varied from 34.52 to 289.21 μg/m³ with an average of 181.50 ± 87.38 μg/m³ (for summer season) and it ranged between 44.04 and 300.02 μg/m³ with an average of 191.04 ± 87.98 μg/m³ (winter season), respectively. No significant difference between particulate concentration and weather parameters was observed. Similarly, results of air quality index (AQI) and pollution index (PI) stated that the air quality of Faisalabad ranges from poor to severely pollute. In terms of AQI, moderate pollution was recorded on sampling sites in the following order; Ittehad Welfare Dispensary > Saleemi Chowk > Kashmir Road > Pepsi Factory, while at Nazria Pakistan Square and Allied Hospital, higher AQI values were recorded. The analysis and results presented in this study can be used by policy-makers to apply rigorous strategies that decrease air pollution and the associated health effects in Faisalabad. Full article

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22 pages, 3613 KiB

Open AccessArticle

Impact of the ‘13th Five-Year Plan’ Policy on Air Quality in Pearl River Delta, China: A Case Study of Haizhu District in Guangzhou City Using WRF-Chem

by Juanming Zhan, Minyi Wang, Yonghong Liu, Chunming Feng, Ting Gan, Li Li, Ruiwen Ou and Hui Ding

Appl. Sci. 2020, 10(15), 5276; https://doi.org/10.3390/app10155276 - 30 Jul 2020

Cited by 7 | Viewed by 2440

Abstract

Due to increasingly stringent control policy, air quality has generally improved in major cities in China during the past decade. However, the standards of national regulation and the World Health Organization are yet to be fulfilled in certain areas (in some urban districts [...] Read more.

Due to increasingly stringent control policy, air quality has generally improved in major cities in China during the past decade. However, the standards of national regulation and the World Health Organization are yet to be fulfilled in certain areas (in some urban districts among the cities) and/or certain periods (during pollution episode event). A further control policy, hence, has been issued in the 13th Five-Year Plan (2016–2020, hereafter 13th FYP). It will be of interest to evaluate the air quality before the 13th FYP (2015) and to estimate the potential air quality by the end of the 13th FYP (2020) with a focus on the area of an urban district and the periods of severe pollution episodes. Based on observation data of major air pollutants, including SO₂ (sulphur dioxide), NO₂ (nitrogen dioxide), CO (carbon monoxide), PM₁₀ (particulate matter with aerodynamic diameter equal to or less than 10 μm), PM_2.5 (particulate matter with aerodynamic diameter equal to or less than 2.5 µm) and O₃ (Ozone), the air quality of Haizhu district [an urban district in the Pearl River Delta (PRD), China] in 2015 suggested that typical heavy pollution occurred in winter and the hot season, with NO₂ or PM_2.5 as the key pollutants in winter and O₃ as the key pollutant in the hot season. We also adopted a state-of-the-art chemical transport model, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), to predict the air quality in Haizhu District 2020 under different scenarios. The simulation results suggested that among the emission control scenarios, comprehensive measures taken in the whole of Guangzhou city would improve air quality more significantly than measures taken just in Haizhu, under all conditions. In the urban district, vehicle emission control would account more than half of the influence of all source emission control on air quality. Based on our simulation, by the end of the 13th FYP, it is noticeable that O₃ pollution would increase, which indicates that the control ratio of volatile organic compounds (VOCs) and nitrogen oxides (NO_x) may be unsuitable and therefore should be adjusted. Our study highlights the significance of evaluating the efficacy of current policy in reducing the air pollutants and recommends possible directions for further air pollution control for urban areas during the 13th FYP. Full article

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14 pages, 2229 KiB

Open AccessArticle

Chemical and Biological Characterization of Particulate Matter (PM 2.5) and Volatile Organic Compounds Collected at Different Sites in the Los Angeles Basin

by Arthur K. Cho, Yasuhiro Shinkai, Debra A. Schmitz, Emma Di Stefano, Arantza Eiguren-Fernandez, Aline Lefol Nani Guarieiro, Erika M. Salinas, John R. Froines and William P. Melega

Appl. Sci. 2020, 10(9), 3245; https://doi.org/10.3390/app10093245 - 07 May 2020

Cited by 4 | Viewed by 2056

Abstract

Background: Most studies on air pollution (AP) exposure have focused on adverse health effects of particulate matter (PM). Less well-studied are the actions of volatile organic compounds (VOCs) not retained in PM collections. These studies quantified chemical and biological properties of both PM2.5 [...] Read more.

Background: Most studies on air pollution (AP) exposure have focused on adverse health effects of particulate matter (PM). Less well-studied are the actions of volatile organic compounds (VOCs) not retained in PM collections. These studies quantified chemical and biological properties of both PM2.5 and VOCs. Methods: Samples were collected near the Port of Los Angeles (Long Beach, LB), railroads (Commerce, CM), and a pollution-trapping topography-site (San Bernardino, SB). Quantitative assays were conducted: (1) chemical—prooxidant and electrophile content, (2) biological—tumor necrosis factor-α (TNF-α) and heme oxygenase-1 (HO-1) expression (3), VOC modulation of PM effects and (4), activation of the antioxidant response element (ARE) using murine RAW 264.7 macrophages. Results: SB site samples were the most potent in the chemical and biological assays, followed by a CM railroad site. Only PM2.5 exhibited significant proinflammatory responses. VOCs were more potent than PM2.5 in generating anti-inflammatory responses; further, VOC pretreatment reduced PM-associated TNF-α expression. VOCs significantly increased ARE activation compared to their corresponding PM2.5 which remained at background levels. Conclusion: Ambient VOCs are major contributors to adaptive responses that can modulate PM effects, in vitro, and, as such, need to be included in comprehensive assessments of AP. Full article

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17 pages, 7547 KiB

Open AccessArticle

Transport Pathways and Potential Source Region Contributions of PM_2.5 in Weifang: Seasonal Variations

by Chengming Li, Zhaoxin Dai, Xiaoli Liu and Pengda Wu

Appl. Sci. 2020, 10(8), 2835; https://doi.org/10.3390/app10082835 - 20 Apr 2020

Cited by 23 | Viewed by 2903

Abstract

As air pollution becomes progressively more serious, accurate identification of urban air pollution characteristics and associated pollutant transport mechanisms helps to effectively control and alleviate air pollution. This paper investigates the pollution characteristics, transport pathways, and potential sources of PM_2.5 in Weifang [...] Read more.

As air pollution becomes progressively more serious, accurate identification of urban air pollution characteristics and associated pollutant transport mechanisms helps to effectively control and alleviate air pollution. This paper investigates the pollution characteristics, transport pathways, and potential sources of PM_2.5 in Weifang based on PM_2.5 monitoring data from 2015 to 2016 using three methods: Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT), the potential source contribution function (PSCF), and concentration weighted trajectory (CWT). The results show the following: (1) Air pollution in Weifang was severe from 2015 to 2016, and the annual average PM_2.5 concentration was more than twice the national air quality second-level standard (35 μg/m³). (2) Seasonal transport pathways of PM_2.5 vary significantly: in winter, spring and autumn, airflow from the northwest and north directions accounts for a large proportion; in contrast, in summer, warm-humid airflows from the ocean in the southeastern direction dominate with scattered characteristics. (3) The PSCF and CWT results share generally similar characteristics in the seasonal distributions of source areas, which demonstrate the credibility and accuracy of the analysis results. (4) More attention should be paid to short-distance transport from the surrounding areas of Weifang, and a joint pollution prevention and control mechanism is critical for controlling regional pollution. Full article

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13 pages, 1460 KiB

Open AccessArticle

Improved Interpolation and Anomaly Detection for Personal PM_2.5 Measurement

by JinSoo Park and Sungroul Kim

Appl. Sci. 2020, 10(2), 543; https://doi.org/10.3390/app10020543 - 11 Jan 2020

Cited by 5 | Viewed by 2515

Abstract

With the development of technology, especially technologies related to artificial intelligence (AI), the fine-dust data acquired by various personal monitoring devices is of great value as training data for predicting future fine-dust concentrations and innovatively alerting people of potential danger. However, most of [...] Read more.

With the development of technology, especially technologies related to artificial intelligence (AI), the fine-dust data acquired by various personal monitoring devices is of great value as training data for predicting future fine-dust concentrations and innovatively alerting people of potential danger. However, most of the fine-dust data obtained from those devices include either missing or abnormal data caused by various factors such as sensor malfunction, transmission errors, or storage errors. This paper presents methods to interpolate the missing data and detect anomalies in PM_2.5 time-series data. We validated the performance of our method by comparing ours to well-known existing methods using our personal PM_2.5 monitoring data. Our results showed that the proposed interpolation method achieves more than 25% improved results in root mean square error (RMSE) than do most existing methods, and the proposed anomaly detection method achieves fairly accurate results even for the case of the highly capricious fine-dust data. These proposed methods are expected to contribute greatly to improving the reliability of data. Full article

(This article belongs to the Special Issue Advances in Air Quality Monitoring and Assessment)

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