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18 pages, 10856 KiB

Open AccessArticle

A Study of Expiratory Droplet Dispersion and Deposition Density in an Enclosed Residential Space

by Sahar Kharrufa, Debadatta Panigrahi, Sahar Makky, Abdulrahman Al Muaitah, Othman Aziz and Mhmd Basheer

Buildings 2023, 13(7), 1869; https://doi.org/10.3390/buildings13071869 - 23 Jul 2023

Cited by 1 | Viewed by 804

Abstract

This study attempts to compare the density of human expiratory droplet deposition on commonly exposed/used surfaces of an indoor residential setting by simulating the droplet exhalation using mist sprays filled with a colored medium. The simulation is not an exact replica of a [...] Read more.

This study attempts to compare the density of human expiratory droplet deposition on commonly exposed/used surfaces of an indoor residential setting by simulating the droplet exhalation using mist sprays filled with a colored medium. The simulation is not an exact replica of a human exhale but is designed to reveal the variations between surfaces. The droplets dispersed in expiratory air in an indoor environment can carry microorganisms, both bacteria and viruses, causing respiratory infections. The process involved a human actor performing predefined daily tasks and was followed around by a second actor, who mimicked breath exhalation using mist sprays. The activities included reading a magazine, watching TV, using a mobile phone, a laptop, making tea, receiving visitors, and talking to a friend. Paper surfaces were used to collect the spray pigment. The results were scanned and analyzed by a computer. The output was in the form of percentage and pixel count of colored pigment on each paper. The results showed that the most significant percentage of pigment was received on the surfaces that simulated activities performed closest to the face. The top recipient of pigment by far was the mobile phone, followed by the remote controller, laptop, keyboard, and mouse. The surfaces farthest from the face, such as the floor, received little to no detectable pigment. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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20 pages, 935 KiB

Open AccessArticle

Resuspension of Seeded Particles Containing Live Influenza A Virus in a Full-Scale Laboratory

by Mahender Singh Rawat, Alan D. Roberts, Deborah M. Brown and Andrea R. Ferro

Buildings 2023, 13(7), 1734; https://doi.org/10.3390/buildings13071734 - 08 Jul 2023

Cited by 1 | Viewed by 1161

Abstract

Many respiratory viruses, including influenza and SARS-CoV-2, are transmitted via the emission and inhalation of infectious respiratory aerosols in indoor environments. Resuspended particles from indoor surfaces and clothing can be a major source of airborne microbiological contaminants in indoor environments; however, it is [...] Read more.

Many respiratory viruses, including influenza and SARS-CoV-2, are transmitted via the emission and inhalation of infectious respiratory aerosols in indoor environments. Resuspended particles from indoor surfaces and clothing can be a major source of airborne microbiological contaminants in indoor environments; however, it is unknown whether resuspended viruses contribute substantially to disease transmission. In this study, we investigated the resuspension via human walking activity of influenza A virus H3N2 laboratory strain, which was generated through a nebulizer into a sealed, unventilated biosafety level 2 (BSL-2) laboratory. The mean airborne viral concentrations following the resuspension events (

3.7 \times 10^{3}

viral RNA copies

m^{- 3}

) were two orders of magnitude lower than those following direct emission via the nebulizer (

1.1 \times 10^{5}

viral RNA copies

m^{- 3}

). The calculated resuspension emission factor (normalized ratio of the airborne mass to mass available for resuspension on the surface) of

10^{- 3}

was similar to reported values for 1–2

μ

m particles. Thus, depending on the infectious dose and viability of the virus, resuspension of settled respiratory viruses could lead to transmission, but the risk appears to be much lower than for direct respiratory emissions. To our knowledge, this is the first full-scale experimental study designed to quantify virus resuspension. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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14 pages, 477 KiB

Open AccessArticle

Adjustment of Matrix Effects in Analysis of 36 Secondary Metabolites of Microbial and Plant Origin in Indoor Floor Dust Using Liquid Chromatography-Tandem Mass Spectrometry

by Cornelius Rimayi and Ju-Hyeong Park

Buildings 2023, 13(5), 1112; https://doi.org/10.3390/buildings13051112 - 22 Apr 2023

Viewed by 942

Abstract

Exposure to microbial agents in water-damaged buildings is a major public health concern. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become a primary tool for testing environmental samples for microbial secondary metabolites (SMs); however, matrix effects can lead to inaccurate results in exposure assessment. [...] Read more.

Exposure to microbial agents in water-damaged buildings is a major public health concern. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become a primary tool for testing environmental samples for microbial secondary metabolites (SMs); however, matrix effects can lead to inaccurate results in exposure assessment. Applying a universal internal standard (ISTD) and a matrix-matched calibration can adjust for matrix effects, as shown by our previous study. However, there are only few isotope-labeled internal standards for SMs available on the market. In this study, we determined the best-performing ISTDs among ten candidates (nine ¹³C-labeled isotopes and one unlabeled analogue) for each of 36 SMs. We analyzed school floor dust spiked with the 36 SMs to identify the best-performing ISTDs (initial experiment) and examined reproducibility with the selected ISTDs and the same spiked dust (validation 1). We also tested applicability for the selected ISTDs using spiked dust collected from different schools (validation 2). The three experiments showed that 26, 17, and 19 SMs had recoveries within the range 100 ± 40%. ¹³C-ochratoxin A and ¹³C-citrinin were most frequently selected as the best ISTDs for the 36 SMs, followed by deepoxy-deoxynivalenol, ¹³C-sterigmatocystin, and ¹³C-deoxynivalenol. Our study shows that using the identified, best-performing analogous ISTDs for those metabolites may improve testing accuracy for indoor dust and help better estimate exposure effects on potential health. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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24 pages, 5903 KiB

Open AccessArticle

Managing Building Water Disruptions in a Post-COVID World: Water Quality and Safety Risk Assessment Tool for Academic Institutions and School Settings

by Stephanie C. Griffin, Molly M. Scanlon and Kelly A. Reynolds

Buildings 2023, 13(4), 921; https://doi.org/10.3390/buildings13040921 - 31 Mar 2023

Cited by 2 | Viewed by 2316

Abstract

Fluctuating building occupancy during the COVID-19 pandemic contributed to poor water quality and safety conditions in building water distribution systems (BWDSs). Natural disasters, man-made events, or academic institutional calendars (i.e., semesters or holiday breaks) can disrupt building occupant water usage, which typically increases [...] Read more.

Fluctuating building occupancy during the COVID-19 pandemic contributed to poor water quality and safety conditions in building water distribution systems (BWDSs). Natural disasters, man-made events, or academic institutional calendars (i.e., semesters or holiday breaks) can disrupt building occupant water usage, which typically increases water age within a BWDS. High water age, in turn, is known to propagate poor water quality and safety conditions, which potentially exposes building occupants to waterborne pathogens (e.g., Legionella) associated with respiratory disease or hazardous chemicals (e.g., lead). Other influencing factors are green building design and municipal water supply changes. Regardless of the cause, an increasing number of water management policies require building owners to improve building water management practices. The present study developed a Water Quality and Safety Risk Assessment (WQSRA) tool to address gaps in building water management for academic institutions and school settings. The tool is intended to assist with future implementation of water management programs as the result of pending policies for the built environment. The WQSRA was modeled after water management practices created for controlling water contaminants in healthcare facilities. Yet, a novel WQSRA tool was adapted specifically for educational settings to allow building owners to evaluate risk from water hazards to determine an appropriate level of risk mitigation measures for implementation. An exemplar WQSRA tool is presented for safety, facility, industrial hygiene, and allied professionals to address current gaps in building water management programs. Academic institutions and school settings should examine the WQSRA tool and formulate an organization-specific policy to determine implementation before, during, and after building water-disruptive events associated with natural or man-made disasters. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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18 pages, 5979 KiB

Open AccessArticle

Evaluation of Optimal Mechanical Ventilation Strategies for Schools for Reducing Risks of Airborne Viral Infection

by Ayad Almaimani, Alaa Alaidroos, Moncef Krarti, Emad Qurnfulah and Alok Tiwari

Buildings 2023, 13(4), 871; https://doi.org/10.3390/buildings13040871 - 26 Mar 2023

Cited by 1 | Viewed by 1456

Abstract

Ventilation systems are one of the most effective strategies to reduce the risk of viral infection transmission in buildings. However, insufficient ventilation rates in crowded spaces, such as schools, would lead to high risks of infection transmission. On the other hand, excessive ventilation [...] Read more.

Ventilation systems are one of the most effective strategies to reduce the risk of viral infection transmission in buildings. However, insufficient ventilation rates in crowded spaces, such as schools, would lead to high risks of infection transmission. On the other hand, excessive ventilation rates might significantly increase cooling energy consumption. Therefore, energy-efficient control methods, such as Demand Control Ventilation systems (DCV), are typically considered to maintain acceptable indoor air quality. However, it is unclear if the DCV-based controls can supply adequate ventilation rates to minimize the probability of infection (POI) in indoor spaces. This paper investigates the benefits of optimized ventilation strategies, including conventional mechanical systems (MV) and DCV, in reducing the POI and cooling energy consumption through a detailed sensitivity analysis. The study also evaluates the impact of the ventilation rate, social distancing, and number of infectors on the performance of the ventilation systems. A coupling approach of a calibrated energy model of a school building in Jeddah, KSA, with a validated Wells–Riley model is implemented. Based on the findings of this study, proper adjustment of the DCV set point is necessary to supply adequate ventilation rates and reduce POI levels. Moreover, optimal values of 2 ACH for ventilation rate and 2 m for social distance are recommended to deliver acceptable POI levels, cooling energy use, and indoor CO₂ concentration for the school building. Finally, this study confirms that increasing the ventilation rate is more effective than increasing social distancing in reducing the POI levels. However, this POI reduction is achieved at the cost of a higher increase in the cooling energy. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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18 pages, 591 KiB

Open AccessArticle

Characterization of Cleaning and Disinfection Product Use, Glove Use, and Skin Disorders by Healthcare Occupations in a Midwestern Healthcare Facility

by Lisa Kobos, Kim Anderson, Laura Kurth, Xiaoming Liang, Caroline P. Groth, Lucy England, A. Scott Laney and M. Abbas Virji

Buildings 2022, 12(12), 2216; https://doi.org/10.3390/buildings12122216 - 14 Dec 2022

Cited by 1 | Viewed by 1563

Abstract

Healthcare facility staff use a wide variety of cleaning and disinfecting products during their daily operations, many of which are associated with respiratory or skin irritation or sensitization with repeated exposure. The objective of this study was to characterize the prevalence of cleaning [...] Read more.

Healthcare facility staff use a wide variety of cleaning and disinfecting products during their daily operations, many of which are associated with respiratory or skin irritation or sensitization with repeated exposure. The objective of this study was to characterize the prevalence of cleaning and disinfection product use, glove use during cleaning and disinfection, and skin/allergy symptoms by occupation and identify the factors influencing glove use among the healthcare facility staff. A questionnaire was administered to the current employees at a midwestern Veterans Affairs healthcare facility that elicited information on cleaning and disinfection product use, glove use during cleaning and disinfection, skin/allergy symptoms, and other demographic characteristics, which were summarized by occupation. The central supply/environmental service workers (2% of the total survey population), nurses (26%,), nurse assistants (3%), and laboratory technicians (5%) had the highest prevalence of using cleaning or disinfecting products, specifically quaternary ammonium compounds, bleach, and alcohol. Glove use while using products was common in both patient care and non-patient care occupations. The factors associated with glove use included using bleach or quaternary ammonium compounds and using cleaning products 2–3 or 4–5 days per week. A high frequency of glove use (≥75%) was reported by workers in most occupations when using quaternary ammonium compounds or bleach. The use of alcohol, bleach, and quaternary ammonium compounds was associated with skin disorders (p < 0.05). These research findings indicate that although the workers from most occupations report a high frequency of glove use when using cleaning and disinfection products, there is room for improvement, especially among administrative, maintenance, and nursing workers. These groups may represent populations which could benefit from the implementation of workplace interventions and further training regarding the use of personal protective equipment and the potential health hazards of exposure to cleaning and disinfecting chemicals. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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19 pages, 3444 KiB

Open AccessArticle

Air Pollution with Fine Particles in Closed Parking and Theoretical Studies of the Interaction of Inhaled Particles in Respiratory Tract

by Aleksandras Chlebnikovas and Raimondas Jasevičius

Buildings 2022, 12(10), 1696; https://doi.org/10.3390/buildings12101696 - 15 Oct 2022

Cited by 5 | Viewed by 1475

Abstract

Indoor air quality must be considered important in regards to its possible harmful effects on the human body. Premises such as underground garages, covered car parks and other similar structures remain crucial in assessing the level of air pollution. In such an environment, [...] Read more.

Indoor air quality must be considered important in regards to its possible harmful effects on the human body. Premises such as underground garages, covered car parks and other similar structures remain crucial in assessing the level of air pollution. In such an environment, the main sources of pollution are motor vehicles, emissions from the heating-ventilation-air-conditioning systems of the engineering networks of the joint building, and pollution. When visiting such premises, a person inhales the air, which contains fine particulate matter and a variety of gaseous pollutants harmful to health. The aim of this study is to assess indoor air pollution with fine particulate matter of 0.3–10 µm depending on the nature of the source, aerodynamic parameters in relation to the potential location of a person, and the mechanical behavior of inhaled particles with respiratory tissues. In this work, the interaction of a fine particle with an alveolar cell is theoretically studied when the particle enters the lungs through the human respiratory tract. Based on the results of this study, it would be possible to assess the extent of pollution and the movement or accumulation of particles in the respiratory system. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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16 pages, 3159 KiB

Open AccessArticle

Analysis of Particulate and Microbiological Filtration Performance of Air Handling Unit Filters in a Low-Energy Office Building over 12 Months

by Gaëtan Pavard, Aurélie Joubert, Yves Andrès and Pierre Le Cann

Buildings 2022, 12(9), 1475; https://doi.org/10.3390/buildings12091475 - 17 Sep 2022

Cited by 1 | Viewed by 1874

Abstract

Indoor air quality is an important consideration for the health and well-being of building occupants, and the SARS CoV-2 pandemic highlighted the importance of maintaining proper ventilation in buildings. Air handling units (AHUs) are used to provide fresh air and maintain occupant comfort. [...] Read more.

Indoor air quality is an important consideration for the health and well-being of building occupants, and the SARS CoV-2 pandemic highlighted the importance of maintaining proper ventilation in buildings. Air handling units (AHUs) are used to provide fresh air and maintain occupant comfort. The objective of this work was to study the evolution of filtration efficiency in an AHU fitted with bag filters, installed to treat office air in a low-energy building, over a 12-month period. The particulate filtration efficiency (PFE) and the microbial filtration efficiency (MFE) were quantified by measuring particle size distribution and bacterial and fungal concentration in the air circulating in the AHU. The resulting microbial concentration measurements in the fresh air (between 10²–10³ CFU/m³ for fungi and around 10³ CFU/m³ for bacteria) were higher than those in the extracted air from the offices (between 10¹ and 10² CFU/m³ for fungi and around 10² CFU/m³ for bacteria). The PFE and MFE measured were almost constant throughout the 12 months, with an increase of the filter pressure drop from 70 to 90 Pa. The PFE and MFE were quite comparable for a particle diameter. Therefore, the measurement of PFE is a reliable indicator of the MFE. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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20 pages, 737 KiB

Open AccessArticle

Potential for Exposure to Particles and Gases throughout Vat Photopolymerization Additive Manufacturing Processes

by Lauren N. Bowers, Aleksandr B. Stefaniak, Alycia K. Knepp, Ryan F. LeBouf, Stephen B. Martin, Jr., Anand C. Ranpara, Dru A. Burns and M. Abbas Virji

Buildings 2022, 12(8), 1222; https://doi.org/10.3390/buildings12081222 - 12 Aug 2022

Viewed by 1778

Abstract

Vat photopolymerization (VP), a type of additive manufacturing process that cures resin to build objects, can emit potentially hazardous particles and gases. We evaluated two VP technologies, stereolithography (SLA) and digital light processing (DLP), in three separate environmental chambers to understand task-based impacts [...] Read more.

Vat photopolymerization (VP), a type of additive manufacturing process that cures resin to build objects, can emit potentially hazardous particles and gases. We evaluated two VP technologies, stereolithography (SLA) and digital light processing (DLP), in three separate environmental chambers to understand task-based impacts on indoor air quality. Airborne particles, total volatile organic compounds (TVOCs), and/or specific volatile organic compounds (VOCs) were monitored during each task to evaluate their exposure potential. Regardless of duration, all tasks released particles and organic gases, though concentrations varied between SLA and DLP processes and among tasks. Maximum particle concentrations reached 1200 #/cm³ and some aerosols contained potentially hazardous elements such as barium, chromium, and manganese. TVOC concentrations were highest for the isopropyl alcohol (IPA) rinsing, soaking, and drying post-processing tasks (up to 36.8 mg/m³), lowest for the resin pouring pre-printing, printing, and resin recovery post-printing tasks (up to 0.1 mg/m³), and intermediate for the curing post-processing task (up to 3 mg/m³). Individual VOCs included, among others, the potential occupational carcinogen acetaldehyde and the immune sensitizer 2-hydroxypropyl methacrylate (pouring, printing, recovery, and curing tasks). Careful consideration of all tasks is important for the development of strategies to minimize indoor air pollution and exposure potential from VP processes. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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17 pages, 7181 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Investigation of Ventilation Systems to Improve Air Quality in the Occupied Zone in Office Buildings

by Szabolcs Szekeres, Attila Kostyák, Ferenc Szodrai and Imre Csáky

Buildings 2022, 12(4), 493; https://doi.org/10.3390/buildings12040493 - 15 Apr 2022

Cited by 14 | Viewed by 2322

Abstract

As a result of COVID-19, many office buildings around the world have downsized their employees, but the comfort parameters in the building had to be kept. The facilities operation rearranged the workstations to keep physical distance and placed plexiglass sheets on the desks [...] Read more.

As a result of COVID-19, many office buildings around the world have downsized their employees, but the comfort parameters in the building had to be kept. The facilities operation rearranged the workstations to keep physical distance and placed plexiglass sheets on the desks for physical protection. A series of measurements have been carried out with workstation set-ups to examine the fresh air rate in the occupied zone. The effect of plexiglass sheets placed on the desks was also examined to see how it changes the airflow pattern in the occupied zone. As the sheets act as a barrier, the primary air does not reach the occupied zone, therefore, the fresh air rate is less. To modify the properties of the ceiling diffusers a new air-ventilation service element was developed. This attachment allows modifying the properties of the ceiling diffusers. Simulations were made at the relevant zones to validate the measurements. Based on design software, the fresh air ratio for a standard ceiling swirl diffuser is 2.46 v% (volume percentage). A numerical model was used to show the fresh air ratio with the system elements for the two different table arrangements, which were 18.3 v% and 21.4 v%, respectively. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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17 pages, 4801 KiB

Open AccessArticle

Simulation Study of a Novel Cylindrical Micro-Electrostatic Particulate Air Filter with High Filtration Efficiency and Low Resistance

by Junyi He, Junjie Liu, Lingchang Kong, Pan Wang and Xin Zhang

Buildings 2021, 11(10), 465; https://doi.org/10.3390/buildings11100465 - 11 Oct 2021

Cited by 2 | Viewed by 2043

Abstract

The purification of indoor pathogenic microorganisms has become a topic of concern. The use of nonwoven media air filters causes high resistance, and the problem of noise limited their application under high air volume. Thus, we propose a micro-electrostatic filter, which has improved [...] Read more.

The purification of indoor pathogenic microorganisms has become a topic of concern. The use of nonwoven media air filters causes high resistance, and the problem of noise limited their application under high air volume. Thus, we propose a micro-electrostatic filter, which has improved performance compared to an electrostatic filter, with a new type of cylindrical structure to tackle indoor pathogenic microbial aerosol pollution. Through simulation, it is found that the filtration performance of a cylindrical structure is better than that of a plate structure under all simulation conditions. For particles larger than 1 μm, the shortest theoretical length of the dust collecting plate required for the cylindrical structure is 34% shorter than that for the plate structure. For 0.1 μm particles, the filtration efficiency of the cylindrical structure is nearly 20~30% (the maximum value is 29.76%) higher than that of the plate structure, while the air velocity is 1.5 m/s~2.5 m/s. The resistance of the cylindrical micro-electrostatic filter is only half of that of the combined plate type micro-electrostatic filter, indicating that the cartridge structure has enormous energy-saving potential. The introduction of the quality factor further proves that the integrated filtration performance of the cartridge micro-electrostatic filter is better. The application of cylindrical micro-electrostatic filters in HVAC systems can help improve indoor air quality and reduce health risks. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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17 pages, 3412 KiB

Open AccessFeature PaperProtocol

NIOSH Dampness and Mold Assessment Tool (DMAT): Documentation and Data Analysis of Dampness and Mold-Related Damage in Buildings and Its Application

by Ju-Hyeong Park and Jean M. Cox-Ganser

Buildings 2022, 12(8), 1075; https://doi.org/10.3390/buildings12081075 - 23 Jul 2022

Cited by 4 | Viewed by 2898

Abstract

Indoor dampness and mold are prevalent, and the exposure has been associated with various illnesses such as the exacerbation of existing asthma, asthma development, current asthma, ever-diagnosed asthma, bronchitis, respiratory infection, allergic rhinitis, dyspnea, wheezing, cough, upper respiratory symptoms, and eczema. However, assessing [...] Read more.

Indoor dampness and mold are prevalent, and the exposure has been associated with various illnesses such as the exacerbation of existing asthma, asthma development, current asthma, ever-diagnosed asthma, bronchitis, respiratory infection, allergic rhinitis, dyspnea, wheezing, cough, upper respiratory symptoms, and eczema. However, assessing exposures or environments in damp and moldy buildings/rooms, especially by collecting and analyzing environmental samples for microbial agents, is complicated. Nonetheless, observational assessment (visual and olfactory inspection) has been demonstrated as an effective method for evaluating indoor dampness and mold. The National Institute for Occupational Safety and Health developed an observational assessment method called the Dampness and Mold Assessment Tool (DMAT). The DMAT uses a semi-quantitative approach to score the level of dampness and mold-related damage (mold odor, water damage/stains, visible mold, and wetness/dampness) by intensity or size for each of the room components (ceiling, walls, windows, floor, furnishings, ventilation system, pipes, and supplies and materials). Total or average room scores and factor-or component-specific scores can be calculated for data analysis. Because the DMAT uses a semi-quantitative scoring method, it better differentiates the level of damage compared to the binary (presence or absence of damage) approach. Thus, our DMAT provides useful information on identifying dampness and mold, tracking and comparing past and present damage by the scores, and prioritizing remediation to avoid potential adverse health effects in occupants. This protocol-type article describes the DMAT and demonstrates how to apply it to effectively manage indoor dampness and mold-related damage. Full article

(This article belongs to the Special Issue Advances in the Indoor Environments and Respiratory Health)

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