Indoor Air Concentrations Research Articles

Indoor Airborne Microplastics: Human Health Importance and Effects of Air Filtration and Turbulence

Microplastics (MPs) are omnipresent particles that receive special attention because of their persistent nature and their potential impact on human disease and on the environment. Most MPs are generated by the degradation of larger plastic items such as clothing, car tires, and discarded plastic materials. In indoor environments, where human beings spend most of their time, aerial MP levels are higher, and the majority are fibers produced from textiles. Airborne MPs indoors are a greater potential danger to humans than MPs ingested in food and drink. Fragments small enough to remain substantially suspended in the air column, the small airborne microparticles that are measured as PM10 and PM2.5, become available for assimilation by human beings through respiration, potentially producing various health problems. Larger MPs act by ingestion and skin contact. MPs can carry microorganisms and micropollutants adsorbed to their surfaces, facilitating their uptake and survival within the human body. Indoor airborne MPs thus represent emerging pollutants of fast-growing concern that are especially important as potential invaders of the human respiratory system, reaching the alveoli of the lungs and finally entering the circulatory system and other tissues. Since this direct human exposure to MP contamination via indoor air is so important, we discuss in this article the ways in which MP concentration and dispersal in indoor air can be affected by air turbulence that is induced by anthropogenic objects such as air conditioners, filters, and purifiers. Much evidence is equivocal and further research is necessary.

Schools and Indoor Air Quality: seasonal variation

Abstract Background Indoor Air Quality (IAQ) in schools is a public health concern, given the vulnerability of children as a demographic group and substantial amount of time that they spend in (highly occupied) classrooms. Conditions specific for school buildings, as well as location and outdoor air quality (OAQ), can adversely affect IAQ and children’s health. The aim of this study was to examine the seasonal variation in IAQ and the influence of OAQ herein in primary schools. Methods Sampling was carried out in summer and winter in 5 schools in central Poland. A culture-dependent method using impactors was applied to examine the total number of bacteria and fungi. Gas chromatography with flame ionization detector (quartz filters for sampling) was applied to determine concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), crucial for their health impact. Results In poorly ventilated classrooms bacteria levels exceeded that of fungi. Bacterial contamination decreased in efficiently ventilated rooms, and before/after the lessons. In summer fungi concentration in indoor air was higher than in winter and reached the level of fungi outdoors. PAHs concentrations (especially those with 4 and more rings, which are biologically active) and the mutagenicity and carcinogenicity equivalents were elevated in winter and related to changes in concentrations in outdoor air. Conclusions IAQ in schools depends on a season. Occupants in classrooms are the main source of bacteria, but the type and number of microorganisms also depend on ventilation conditions. PAHs characteristic of coal/wood combustion indicates that in the absence of internal emission sources, external sources most likely affect IAQ in schools in winter.

Air pollution by BTEX and the related health risks due to the tobacco smoke, a systematic review

BTEX is a group of hazardous chemical compounds that include benzene, toluene, ethylbenzene, and xylene. The indoor concentration of BTEX is mostly influenced by tobacco smoking, the region within the house, and seasonal variations. This systematic review analyzed studies on BTEX concentrations in indoor air, using data from Google Scholar, Science Direct, and Springer from 2010 to 2020, and performed statistical analysis with R after thorough data extraction and evaluation. Duplicate studies were removed, and disagreements during the article selection process were resolved by a third reviewer. Out of the 1351 articles obtained from the keyword search, only 13 were eventually selected for this study. The most abundant compound found in houses among BTEX was toluene, with a concentration of 13.80±16.50 µg/m3. The results indicated that the concentration of ƩBTEX in houses where smoking occurred was lower than in houses where no smoking occurred (18.52 vs. 27.66 µg/m3); However, the concentration of benzene in smoking houses was higher than in non-smoking houses (7.17±9.42 vs. 2.65±3.77 µg/m3, unpaired Wilcoxon test: p>0.05). The concentration of BTEX in houses was substantially lower than that in cafes (21.10±31.10 vs. 15,100±9740 µg/m3, unpaired Wilcoxon test: p<0.05). The urban region had the most significant accumulation of all BTEXs, with the industrial and rural sectors following suit. The findings indicated that the average concentration of BTEX in warm months (such as spring and summer) were higher than in cold months (such as fall and winter) within houses (28.50±44.30 vs. 8.60±7.77 µg/m3, unpaired Wilcoxon test: p>0.05). The findings indicated that the Cancer Risk (CR) associated with houses (3.11×10-6) and cafes (3.54×10-3) exceeded the permissible threshold. Moreover, the waterpipe cafes that utilized fruit-flavored tobacco had the greatest CR (4.98×10-3). Furthermore, the presence of smoking, regional factors, and seasonal variations did not result in an increase in the hazard quotient (HQ) in houses beyond the acceptable thresholds. Finally, smoking, seasonal variations, and region had critical impact on indoor BTEX concentrations, and they could increase the risk of carcinogenic potential in the indoor environments.

Peracetic Acid Emissions and Exposures during Building Disinfection Events

Since the onset of the COVID-19 pandemic, there has been a significant increase in chemical disinfection of high-touch surfaces in buildings. Peracetic acid (PAA) is a commercially available and widely used disinfectant for inactivation of viruses and bacteria. The objective of this study is to evaluate indoor PAA emissions and exposures during full-scale building disinfection events via real-time PAA measurement in a test house. The measurements revealed that PAA-based surface disinfection can lead to a significant increase in PAA concentrations in indoor air (0.1–1 mg/m3). PAA emission factors (EFs) for spray-based products ranged from 0.22–0.59 mg of PAA emitted per mg of PAA sprayed, indicating that a significant fraction of the PAA applied to surfaces is emitted into the indoor atmosphere. Inhalation intake fractions (iFs) ranged from 1,597–3,436 ppm for a one-hour exposure period, demonstrating that around 0.16–0.34% of the PAA emitted into indoor air can be inhaled by an occupant during a disinfection event. iFs were similar between the active disinfection period and the subsequent concentration decay period, suggesting that inhalation intake is important both during and after the disinfectant is applied. Real-time breathing zone (BZ) experiments demonstrated that occupants can be exposed to elevated PAA concentrations beyond those measured in the bulk indoor air due to the source-to-BZ proximity effect inherent in disinfection processes. The PAA EFs enabled modeling of PAA dynamics in different indoor environments. Model results show that PAA concentrations often exceed exposure limits, indicating a need for improved exposure mitigation strategies.

Residential proximity to conventional and unconventional wells and exposure to indoor air volatile organic compounds in the Exposures in the Peace River Valley (EXPERIVA) study

BackgroundIn a previous study located in Northeastern British Columbia (Canada), we observed associations between density and proximity of oil and gas wells and indoor air concentrations of certain volatile organic compounds (VOCs). Whether conventional or unconventional well types and phases of unconventional development contribute to these associations remains unknown. ObjectiveTo investigate the associations between proximity-based metrics for conventional and unconventional wells and measured indoor air VOC concentrations in the Exposures in the Peace River Valley (EXPERIVA) study samples. MethodsEighty-four pregnant individuals participated in EXPERIVA. Passive indoor air samplers were analyzed for 47 VOCs. Oil and gas well legacy data were sourced from the British Columbia Energy Regulator. For each participant's home, 5 km, 10 km and no buffer distances were delineated, then density and Inverse Distance Square Weighted (ID2W) metrics were calculated to estimate exposure to conventional and unconventional wells during pregnancy and the VOC measurement period. Multiple linear regression models were used to test for associations between the well exposure metrics and indoor air VOCs. For exposure metrics with >30% participants having a value of 0, we dichotomized exposure (0 vs. >0) and performed ANOVAs to assess differences in mean VOCs concentrations. ResultsAnalyses indicated that: 1) conventional well density and ID2W metrics were positively associated with indoor air acetone and decanal; 2) unconventional well density and ID2W metrics were positively associated with indoor air chloroform and decamethylcyclopentasiloxane, and negatively associated with decanal; 3) drilling specific ID2W metrics for unconventional wells were positively associated with indoor air chloroform. ConclusionOur analysis revealed that the association between the exposure metrics and indoor air acetone could be attributed to conventional wells and the association between exposure metrics and indoor air chloroform and decamethylcyclopentasiloxane could be attributed to unconventional wells.

Dynamics of indoor volatile organic compounds and seasonal ventilation strategies for residential buildings in Northeast China

This study utilized a questionnaire survey to collect data from 265 residents in Changchun, encompassing building characteristics, ventilation frequency and overall satisfaction with the indoor environment. Statistical analysis revealed significant disparities in ventilation frequency and satisfaction with indoor temperature. The survey results indicate that the primary mode of indoor air exchange amongst Changchun residents is window ventilation, accounting for 93%. Field tracking was conducted to measure indoor air concentrations of volatile organic compounds (VOCs) in residential buildings during winter and summer seasons. The study revealed a significant increase in the average indoor/outdoor (I/O) ratio of the targeted 25 VOC concentrations in winter, rising from 10.8 to 17.7. The findings underscore indoor sources as predominant contributors to the measured VOCs. Temperature, humidity and room functions are the main factors affecting VOC concentration. Higher temperatures and increased relative humidity both contributed to elevated indoor VOC levels. This study recommended the opening of more windows during high temperature and high humidity in summer, to maintain good indoor air quality and effectively age the emission of VOCs from furniture. This study contributes to the enhancement of the database on indoor air quality and effective ventilation strategies in cold regions for safeguarding public health.

Microplastics comparison of indoor and outdoor air and ventilation rate effect in outskirts of the Seoul metropolitan city

Microplastics in the air are becoming a concern, especially in indoor environments. Outdoor microplastics can travel from far spaces while indoor ones remain suspended and recirculate in the indoor environment. In this study, we collected air samples from the same buildings indoors and outdoors and observed the indoor microplastic concentration was 1.8 times higher than the outdoor. 24-hour sampling was performed with a mini-volume air sampler at the rate of 5 L/min. In this study, along with a comparison of indoor and outdoor concentrations, we also studied the microplastics' type size, and shape. We found that fiber-type microplastics account for nearly 90 % of the total and synthetic fibers. We also reported the 10 highest present microplastics are Polyethylene, Polyethersulfone, Polyamide, Polystyrene, Acrylic, Polyvinyl Chloride, Polytetrafluoroethylene, Alkyd, and Polyurethane. It is also observed the indoor ventilation rate plays a major role in the microplastic concentrations, long and periodic ventilation resulted in the lower concentration of the indoor microplastics. This study resulted in higher indoor air concentrations than outdoor and even in the outskirts of the metropolitan city which shows that indoor air concentrations are dependent on indoor sources and human activity.

Influence of meteorological conditions on the variability of indoor and outdoor particulate matter concentrations in a selected Polish health resort

The article evaluates air pollution by particulate matter (PM) in indoor and outdoor air in one of the Polish health resorts, where children and adults with respiratory diseases are treated. The highest indoor PM concentrations were recorded during the winter season. Therefore, the maximum average daily concentration values in indoor air for the PM10, PM2.5, and PM1 fractions were 50, 42 and 23 µg/m3, respectively. In the case of outdoor air, the highest average daily concentrations of PM2.5 reached a value of 40 µg/m3. The analyses and backward trajectories of episodes of high PM concentrations showed the impact of supra-regional sources and the influx of pollutants from North Africa on the variability of PM concentrations. The correlation between selected meteorological parameters and PM concentrations shows the relationship between PM concentrations and wind speed. For example, the correlation coefficients between PM1(I) and PM1(O) concentrations and wind speed were − 0.8 and − 0.7 respectively. These factors determined episodes of high PM concentrations during winter periods in the outdoor air, which were then transferred to the indoor air. Elevated concentrations in indoor air during summer were also influenced by chimney/gravity ventilation and the appearance of reverse chimney effect.

Estimation of Formaldehyde Levels in Indoor Air of Gross Anatomy Laboratory

Introduction: Medical students spend majority of their times in Anatomy lab during their first year MBBS. Formalin has attracted attention as a health hazard for students and instructors as formalin concentrations in air of gross anatomy laboratories are often higher than permissible limits. Despite the known toxicity of formaldehyde and its potential health effects, laboratory workers and others have little enthusiasm for reducing or replacing the formaldehyde working solution Materials and Methods: The FA concentration (in ppm) of indoor air in Anatomy laboratory was measured using a SMILEDRIVE Portable air quality pollution meter. The mean FA concentration was measured after 1 hour after the cadavers were shifted to dissection table at three different levels a. At the level of floor b. At the level of roof c. 2 feets above the table (Breathing Zone of medical students) Three air samples from the breathing zones were tested and mean concentration of FA was taken with exhaust fan on at the level of roof and recorded as a. S1R- First immediately before the dissection (Zero hour), b. S2R- Second sample was collected after one hour after first sample was taken (First hour) and c. S3R- Third sample after two hours after first sample was taken (Second hour). Three air samples from the breathing zones were tested and mean concentration of FA was taken with exhaust fan on at the level of floor and recorded as a. S1F- First immediately before the dissection (Zero hour), b. S2F- Second sample was collected after one hour after first sample was taken (First hour) and c. S3F- Third sample after two hours after first sample was taken (Second hour). Results: The vertical distribution of FA was measured by taking the mean air samples at the level of floor, at roof level and about 2 feet above dissection table immediately after the cadavers were shifted to tables. It was found to be about 0.54ppm at the level of floor, 0.52 at the breathing zone and 0.51 ppm at roof level. The FA concentration was highest at the level of floor and least at the level of roof. On comparing S2F and S2R the p value was 1.335. Thus, it was not statistically significant. On comparing S3F and S3R the p value was 0.411. Thus, it was not statistically significant. Conclusion: The mean FA at the level of floor was 0.54 ppm. At the breathing zone the mean FA concentration was 0.51 ppm before the dissection was started. Exhaust fans at the level of roof were switched on and the second sample was taken after 1 hour. The FA concentration was 0.23 ppm. Third sample was taken at 2nd hour and FA concentration was 0.11 ppm. The exhaust fans at the level of floor were switched on. The air samples were measured at 0, 1st and 2nd hour at breathing zones. It was 0.51, 0.31 and 0,15 ppm respectively.

Indoor concentrations of radioactive aerosols from nuclear accidents.

In previous studies, some of the important factors that affect the spread of radioactive aerosols into indoors were considered. The studies were based on a new CFD approach and provided good descriptions for the deposition of aerosol particles inside small spaces and the penetration of aerosols into buildings through wall cracks. In this article, an application of those studies is implemented, where all the graphical relations that are required to estimate the indoor concentrations of radioactive aerosols from nuclear accidents are provided. This includes the deposition velocities, deposition rate, and the penetration factor. Particular interest is in the Fukushima-Daiichi nuclear power plant accident that took place in Japan in 2011. The aerosols carrying the radioiodine iodine-131 and the radiocesium cesium-134 and cesium-137 are studied. Based on the model's assumptions, and assuming steady-state air concentrations, the radioactive aerosols' concentrations in indoor air are about 97% of the concentrations in outdoor air. The applications demonstrate the model to be convenient and practical.

Emissions and exposure to NOx, CO, CO2 and PM2.5 from a gas stove using reference and low-cost sensors

Gas stoves and cooking are significant sources of indoor pollution. Using a combination of regulatory and calibrated low-cost sensors (LCS) we measured NO, NO2, CO and CO2 emission rates (g hr−1) and emission factors (g J−1) from a natural-gas stove and oven. The emission rates for gaseous pollutants were significantly higher, by factors of 2.6–29, from the oven compared to the stove for every pollutant measured.To evaluate the indoor air concentrations, we used a calibrated low-cost sensor (TSI Inc, AirAssure) to examine indoor concentration of CO, CO2, NO2 and PM2.5 for one month in one U.S. home with a gas stove during normal activities, including cooking. Indoor concentrations of one or more pollutants exceeded the U.S. EPA's Air Quality Index (AQI) level of 100 (for CO, NO2, and PM2.5) or 2000 ppm (for CO2) for an average of 99 min per day. The AirAssure, with only the manufacturer's calibration, was an excellent indicator of times when indoor concentrations of CO, CO2, and NO2 exceeded these reference levels. Without in-situ calibration, the AirAssure underestimated in-home PM2.5 concentrations. After in-situ calibration, the AirAssure correctly identified 1-min periods when the AQI was >100 85% of the time (up from 46% of the time without calibration).

Synergistic interaction of co-exposure to humidifier disinfectant chemicals CMIT/MIT and PHMG in lung injury.

A number of biocidal disinfectant chemicals are used as household products to prevent spread of pathogens. People are commonly exposed to multiple chemicals through those disinfectants. However, effects of interactions (e.g., synergism) between disinfectants on human health outcomes have been rarely studied. In this study, we aimed to investigate associations of a mixture of chloromethylisothiazolinone/methylisothiazolinone (CMIT/MIT) and polyhexamethylene guanidine (PHMG), which had been used as humidifier disinfectants (HDs) in South Korea, with HD-associated lung injury (HDLI) in a Korean population (n = 4058) with HD exposure through use of HD products. Exposure to HD was retrospectively assessed by an interview-based standardized survey, and HDLI was determined by clinical assessment. After adjusting for covariates, PHMG-specific exposure indices (e.g., amount of use, indoor air concentration, and weekly exposure level) were dose-dependently associated with HDLI (their odds ratios for the comparison of third tertile versus first tertile were 1.95, 1.77, and 2.16, respectively). CMIT/MIT exposure was not observed to have a significant association with HDLI in a single chemical exposure model; however, associations between PHMG exposure and HDLI were strengthened by co-exposure to CMIT/MIT in combined chemical exposure models, where synergistic interactions between CMIT/MIT use and PHMG indices (amount of use and weekly exposure level) were observed (p-interaction in additive scale: 0.02 and 0.03, respectively). Our findings imply that adverse effects of PHMG exposure on lung injury among HD users might be worsened by co-exposure to CMIT/MIT. Given that plenty of household products contain disinfectants on global markets, epidemiological and toxicological investigations are warranted on interaction effects of co-exposure to disinfectants.

Relevance of radon progeny measurements for the assessment of inhalation doses in groundwater utilities

The high radon concentrations measured in the indoor air of groundwater facilities and the prevalence of the problem have been known for several years. Unlike in other workplaces, in groundwater plants, radon is released into the air from the water treatment processes. During the measurements of this study, the average radon concentrations varied from 500 to 8800 Bq m–3. In addition, the indoor air of the treatment plants is filtered and there are no significant internal aerosol sources. However, only a few published studies on groundwater plants have investigated the properties of the radon progeny aerosol, such as the equilibrium factor (F) or the size distribution of the aerosol, which are important for assessing the dose received by workers. Moreover, the International Commission on Radiological Protection has not provided generic aerosol parameter values for dose assessment in groundwater treatment facilities. In this study, radon and radon progeny measurements were carried out at three groundwater plants. The results indicate surprisingly high unattached fractions (fp = 0.27–0.58), suggesting a low aerosol concentration in indoor air. The corresponding F values were 0.09–0.42, well below those measured in previous studies. Based on a comparison of the effective dose rate calculations, either the determination of the fp or, with certain limitations, the measurement of radon is recommended. Dose rate calculation based on the potential alpha energy concentration alone proved unreliable.

Impact of indoor air pollution exposure from traditional stoves on lung functions in adult women of a rural Indian district

Introduction: Biomass Fuels (BMF) used for daily cooking in developing countries inside home is the highest exposures to air pollutants. Inhalation of these pollutants causes harmful health effects. This study aims to assess the health effects with the indoor air pollutants generated BMF.
 Materials and methods: A cross-sectional study, conducted in a rural village of India. 450 households were divided into two groups based on the cooking fuel, the BMF group and the Liquefied Petroleum Gas (LPG) clean fuel group. Socioeconomic and respiratory symptoms information was obtained using a standard questionnaire. Indoor air concentration for PM10 and PM2.5 was measured during cooking hours. Pulmonary Function Tests (PFTs) were conducted for the women inhabitants using spirometer.
 Results: Respiratory symptoms like chest pain, breathlessness, eye irritation, and blackout found to be significantly higher in biomass users (P<0.05). Moreover, an increasing trend in the prevalence of symptoms/ morbid conditions observed with an increase in exposure.
 Conclusion: Findings of the study confirms that the traditional use of biomass fuels exposes all family members daily to air pollution levels that well exceed available health guidelines for indoor air quality and highlights the critical gender and age dimensions of the Household Air Pollution (HAP) problem. Women exposed to BMF smoke suffer more from health problems and are at higher risk of respiratory illnesses than other fuel users.

Impact of Hurricanes, Tropical Storms, and Coastal Extratropical Storms on Indoor Air VOC Concentrations

AbstractUnderstanding vapor intrusion (VI) temporal variability is key for the design of sampling strategies intended to assess reasonable maximum exposure of indoor air concentrations of volatile organic compounds (VOCs) as well as risk evaluation and mitigation planning. VI temporal variability has previously been shown to be dependent on the complex interactions of multiple independent variables—meteorological, hydrogeological, and human behavioral. Several meteorological variables, including barometric pressure, wind speed, and rainfall, are linked during tropical and extratropical storm events. High‐frequency meteorological and indoor VOC data from a series of seven tropical storms and four extratropical storms were collected at a single industrial building with multiple heating, ventilation, and air conditioning (HVAC) zones. The storms and sampling zones showed a variety of effects on trichloroethylene (TCE) concentrations in indoor air. In one zone (supply room), increases in TCE concentrations often, but not always, closely coincided with decreasing barometric pressure, sustained wind speeds over 32 km/h (20 mph), and differential pressures indicating subslab to indoor flow. A second zone, in a restroom, did not show a consistent pattern of temporal correlation between meteorological factors and indoor air concentrations. While peak indoor air concentrations may be associated with the passage of cyclonic storms at some sampling locations, this does not appear to be generalizable to all sampling locations. The observed increase in indoor air concentration potentially attributable to these storms is typically less than an order of magnitude and the duration ranges from a day to a week.

Indoor air quality in Kazakh households: Evaluating PM2.5 levels generated by cooking activities

AbstractThe present study introduces a concentration estimation model for indoor inhalable fine particles (PM2.5) during cooking activities in typical Kazakh houses, which are generally poorly ventilated with high emission levels. The aim of the present work is to identify factors influencing PM2.5 concentrations during cooking and elucidate the mechanisms underlying the build‐up and reduction of PM2.5 concentrations. These are achieved through a methodology that combines PM2.5 sampling, monitoring, and modeling to predict household PM2.5 levels and estimate daily concentrations. Specifically, USEPA's IAQX v1.1 was employed to simulate the one‐zone concept (kitchen) for concentrations related to cooking activities in several households. The results reveal that PM2.5 concentrations varied between 13 and 266 μg/m3 during cooking activities. Factors such as kitchen size, air exchange characteristics, and the type of food and cooking style were identified as important, influencing the observed concentrations. The model accurately captured concentration trends (R > 0.9). However, certain predictions tended to overestimate the measurements, attributing to inaccuracies in selecting air exchange and emission rates. Cooking activities contributed to household air pollutant (HAP) PM2.5 levels ranging from 9% to 94%. Notably, during the non‐heating period of the year (corresponding to the warmer half of the year), the impact of cooking became more significant and was identified as a major contributor to indoor PM2.5 concentrations. Conversely, during the heating period (i.e., the colder part of the year), outdoor PM levels and household ventilation practices played primary roles in regulating indoor air concentrations. This present study presents one of the initial efforts to assess household air pollutants in Central Asia, providing foundation and insights into the indoor air quality of Kazakh houses, where the understanding of indoor air quality remains limited. Future research recommendations include developing advanced models that account for individual activity patterns and specific house types for improved accuracy and representativeness.

External liquid calibration method for iodide chemical ionization mass spectrometry enables quantification of gas-phase per- and polyfluoroalkyl substances (PFAS) dynamics in indoor air.

Per- and polyfluoroalkyl substances (PFAS) are manufactured chemicals that have been detected across the globe. Fluorotelomer alcohols (FTOHs) are one PFAS class commonly found in indoor air due to emissions from consumer products (e.g., textiles and food packaging) and are human metabolic, atmospheric oxidative, and industrial precursors of perfluoroalkyl carboxylic acids (PFCAs). We developed a quantitative method for real-time analysis of gas-phase FTOHs, perfluoroalkyl acids (PFCAs and GenX), one perfluorooctane sulfonamide (EtFOSA), one fluorotelomer diol (FTdiOH), and one fluorinated ether (E2) using high-resolution time-of-flight chemical ionization mass spectrometry equipped with iodide reagent ion chemistry (I-HR-ToF-CIMS). Herein, we present a direct liquid injection method for external calibration, providing detection limits of 0.19-3.1 pptv for 3 s averaging and 0.02-0.44 pptv for 120 s averaging, with the exception of E2, which had detection limits of 1700 and 220 pptv for 3- and 120 s averaging, respectively. These calibrations enabled real-time gas-phase quantification of 6 : 2 FTOH in room air while microwaving popcorn, with an average peak air concentration of 31.6 ± 4.5 pptv measured 2 meters from a closed microwave. Additionally, 8 : 2 and 10 : 2 FTOH concentrations in indoor air were measured in the presence and absence of a rain jacket, with observed peak concentrations of 110 and 25 pptv, respectively. Our work demonstrates the ability of I-HR-ToF-CIMS to provide real-time air measurements of PFAS relevant to indoor human exposure settings and allow for PFAS source identification. We expect that real-time quantification of other gas-phase PFAS classes is possible, enabling advances in understanding PFAS sources, chemistry, and partitioning.

Indoor air concentrations of PM2.5 quartz fiber filter-collected ionic PFAS and emissions to outdoor air: findings from the IPA campaign.

Per- and polyfluoroalkyl substances (PFAS) are prevalent in consumer products used indoors. However, few measurements of ionic PFAS exist for indoor air. We analyzed samples collected on PM2.5 quartz fiber filters (QFFs) in 11 North Carolina homes 1-3 times in living rooms (two QFFs in series), and immediately outside each home (single QFF), for 26 ionic PFAS as part of the 9 months Indoor PFAS Assessment (IPA) Campaign. All targeted PFAS, except for PFDS and 8:2 monoPAP, were detected indoors. PFBA, PFHpA, PFHxA, PFOA, PFOS, and 6:2 diPAP were detected in >50% of indoor samples. PFHxA, PFOA, and PFOS had the highest detection frequency (DF = 80%; medians = 0.5-0.7 pg m-3), while median PFBA concentrations (3.6 pg m-3; DF = 67%) were highest indoors. Residential indoor air concentrations (sum of measured PFAS) were, on average, 3.4 times higher than residential outdoor air concentrations, and an order of magnitude higher than regional background concentrations. Indoor-to-outdoor emission rate estimates suggest that emissions from single unit homes could be a meaningful contributor to PFBA, PFOA, and PFOS emissions in populated areas far from major point sources. Backup QFFs were observed to adsorb some targeted PFAS from the gas-phase, making reported values upper-bounds for particle-phase and lower-bounds for total air (gas plus particle) concentrations. We found that higher concentrations of carbonaceous aerosol were associated with a shift in partitioning of short chain PFCAs and long chain PFSAs toward the particle phase.

Investigation of Formaldehyde Concentration in Indoor and Outdoor Air, A Systematic Review

Formaldehyde, commonly recognized as formalin, stands as the archetypal aldehyde, distinguished by its colorless gaseous form and acrid scent. Widespread usage and dissemination of this compound pose potential risks of dermatological and ocular irritation, respiratory ailments, genetic alterations, and carcinogenesis. This study aims to explore the concentrations of formaldehyde in both indoor and outdoor environments. The search strategy involved querying English-language articles in Google Scholar and Science Direct databases, specifically selecting those detailing formaldehyde concentrations. Ultimately, 16 articles meeting the criteria were included in the study. Results reveal that outdoor formaldehyde mean concentration reached up to 17.02 ± 11.46 ppm, while indoor level was 0.528 ± 0.527 ppm. Industrial settings exhibited the highest concentrations, with a mean of 10.73 ± 4.5 ppm. The study exposes higher formaldehyde levels in Asian countries (0.0522 ± 0.075 ppm) compared to European and North American counterparts. Additionally, concentrations displayed a tendency to rise during the summer (3.57 ± 5.03 ppm) in contrast to the winter season (3.08 ± 5.03 ppm). These findings underscore the need for heightened awareness and regulatory measures to mitigate formaldehyde exposure, especially in industrial contexts and regions with elevated concentrations.

Evaluation of the performance of bituminous geomembranes (BGMs) as vapour barriers

Vapour barriers (VBs) are essential in maintaining the indoor air quality of home basements or industrial facilities, especially when subsurface contamination poses a risk to human health. It is of utmost importance that the material installed as VB has the capacity to prevent contaminant migration into the indoor air space and reduce its concentration to an acceptable limit. Bituminous geomembranes (BGMs) have been used as contaminant barriers in spite of the gap in research regarding the permeation of volatile organic compounds (VOCs) through BGMs. This study examines the performance of a 4.1mm thick elastomeric BGM as a diffusive barrier to four commonly found VOCs; benzene, toluene, ethylbenzene, and xylenes (BTEX), utilizing computer modelling of contaminant migration from a contaminated soil source to a hypothetical warehouse building constructed on a brownfield site. The effectiveness of BGM in preventing vapour intrusion is evaluated based on its capacity to keep the indoor air concentration of the contaminant below the recommended exposure limits (RELs). Based on the modelling results, the BGM can be expected to perform as a very efficient VB for the simulated warehouse if quality control can be ensured during installation. This modelling approach can be adopted to investigate BGMs’ performance in different remediated site scenarios to make scope for a robust decision-making process regarding the construction and the engineering control requirements.