Indoor air quality and sick-building syndrome at a metro station in Tianjin, China.

Metro systems play a crucial role in public transportation worldwide. Given that metro stations are unique built environments with a significant volume of daily commuters, ensuring a satisfactory air quality in these spaces becomes paramount. This study involved measurements of indoor air quality (IAQ), staff satisfaction, particulate matter (PM) chemical composition, and heavy metal health risks at a typical metro station in Tianjin over two seasons. Although the air exchange rate was sufficient to maintain a CO2 concentration less than 1000 ppm, the proportion of staff reporting no sick-building symptoms decreased from 83 % in spring to 25 % in winter. An average mass concentration of PM with an aerodynamic diameter smaller than 2.5 µm (PM2.5) of 68.0 ± 42.2 µg/m3 and an average PM1 mass concentration of 51.8 ± 33.3 µg/m3 were observed on the platform in winter. PM2.5 contained more metal in winter than in spring. PM2.5 in winter contained more metal in winter than in spring. With a lower relative humidity in winter, the coefficient of friction between railway wheels and rails increased, thus increasing particle emission. The carcinogenic risk of Cr on the platform was unacceptable. Moreover, the health risks induced by Ba should be investigated. The findings indicate that PM control at metro stationss, particularly on platforms in winter, should be emphasized.

To breathe or not to breathe: Inhalational exposure to heavy metals and related health risk.

This study reviewed scientific literature on inhalation exposure to heavy metals (HMs) in various indoor and outdoor environments and related carcinogenic and non-carcinogenic risk. A systematic search in Web of Science, Scopus, PubMed, Embase, and Medline databases yielded 712 results and 43 articles met the requirements of the Population, Exposure, Comparator, and Outcomes (PECO) criteria. Results revealed that HM concentrations in most households exceeded the World Health Organization (WHO) guideline values, indicating moderate pollution and dominant anthropogenic emission sources of HMs. In the analyzed schools, universities, and offices low to moderate levels of air pollution with HMs were revealed, while in commercial environments high levels of air pollution were stated. The non-carcinogenic risk due to inhalation HM exposure exceeded the acceptable level of 1 in households, cafes, hospitals, restaurants, and metros. The carcinogenic risk for As and Cr in households, for Cd, Cr, Ni, As, and Co in educational environments, for Pb, Cd, Cr, and Co in offices and commercial environments, and for Ni in metros exceeded the acceptable level of 1 × 10-4. Carcinogenic risk was revealed to be higher indoors than outdoors. This review advocates for fast and effective actions to reduce HM exposure for safer breathing.

Assessment of Portuguese fitness centers: Bridging the knowledge gap on harmful microbial contamination with focus on fungi.

The lack of knowledge regarding the extent of microbial contamination in Portuguese fitness centers (FC) puts attendees and athletes at risk for bioaerosol exposure. This study intends to characterize microbial contamination in Portuguese FC by passive sampling methods: electrostatic dust collectors (EDC) (N = 39), settled dust (N = 8), vacuum filters (N = 8), and used cleaning mops (N = 12). The obtained extracts were plated in selective culture media for fungi and bacteria. Filters, EDC, and mop samples' extracts were also screened for antifungal resistance and used for the molecular detection of the selected Aspergillus sections. The detection of mycotoxins was conducted using a high-performance liquid chromatograph (HPLC) system and to determine the cytotoxicity of microbial contaminants recovered by passive sampling, HepG2 (human liver carcinoma) and A549 (human alveolar epithelial) cells were employed. The results reinforce the use of passive sampling methods to identify the most critical areas and identify environmental factors that influence microbial contamination, namely having a swimming pool. The cardio fitness area presented the highest median value of total bacteria (TSA: 9.69 × 102 CFU m-2.day-1) and Gram-negative bacteria (VRBA: 1.23 CFU m-2.day-1), while for fungi it was the open space area, with 1.86 × 101 CFU m-2.day-1. Aspergillus sp. was present in EDC and in filters used to collect settled dust. Reduced azole susceptibility was observed in filters and EDC (on ICZ and VCZ), and in mops (on ICZ). Fumonisin B2 was the only mycotoxin detected and it was present in all sampling matrixes except settled dust. High and moderate cytotoxicity was obtained, suggesting that A549 cells were more sensitive to samples' contaminants. The observed widespread of critical toxigenic fungal species with clinical relevance, such as Aspergillus section Fumigati, as well as Fumonisin B2 emphasizes the importance of frequent and effective cleaning procedures while using shared mops appeared as a vehicle of cross-contamination.

Exposure and biomonitoring of PAHs in indoor air at the urban residential area of Iran: Exposure levels and affecting factors.

The concentration of polycyclic aromatic hydrocarbons (PAHs) in the air inside residential houses in Iran along with measuring the amount of 1-OHpyrene metabolite in the urine of the participants in the study was investigated by gas chromatography-mass spectrometry (GC-MS). Demographic characteristics (including age, gender, and body composition), equipment affecting air quality, and wealth index were also investigated. The mean ± standard error (SE) concentration of particulate matter 10 (PM10) and ∑PAHs in the indoor environment was 43.2 ± 1.98 and 1.26 ± 0.15 µg/m3, respectively. The highest concentration of PAHs in the indoor environment in the gaseous and particulate phase related to Naphthalene was 1.1 ± 0.16 µg/m3 and the lowest was 0.01 ± 0. 0.001 µg/m3 Pyrene, while the most frequent compounds in the gas and particle phase were related to low molecular weight hydrocarbons. 30% of the samples in the indoor environment have BaP levels higher than the standards provided by WHO guidelines. 68% of low molecular weight hydrocarbons were in the gas phase and 73 and 75% of medium and high molecular weight hydrocarbons were in the particle phase. There was a significant relationship between the concentration of some PAH compounds with windows, evaporative coolers, printers, and copiers (p < 0.05). The concentration of PAHs in houses with low economic status was higher than in houses with higher economic status. The average concentration of 1-hydroxypyrene metabolite in the urine of people was 7.10 ± 0.76 µg/L, the concentration of this metabolite was higher in men than in women, and there was a direct relationship between the amount of this metabolite in urine and the amount of some hydrocarbon compounds in the air, PM10, visceral fat and body fat. This relationship was significant for age (p = 0.01). The concentration of hydrocarbons in the indoor environment has been above the standard in a significant number of non-smoking indoor environments, and the risk assessment of these compounds can be significant. Also, various factors have influenced the amount of these compounds in the indoor air, and paying attention to them can be effective in reducing these hydrocarbons in the air.

Working with cattle slurry on farms: emission and dispersion of hydrogen sulfide gas during stirring.

Over the past 15 years, there have been numerous fatalities related to working with animal slurry. Working with cattle slurry releases toxic gases, in particular, hydrogen sulphide (H2S), which can cause acute central nervous system toxicity, breathing difficulties, and death if exposed to high concentrations. Real-time measurements of H2S gas were taken over distance and time, during the stirring of cattle slurry on farms. Gas was measured at eight slurry stores with differing typical configurations of indoor or outdoor stores and with or without slatted flooring. Highest H2S gas levels were measured from indoor stores under slatted floors, and generally at positions closest to the stirrer or the point of maximum stirring, with levels decreasing with distance from source. Most of the data indicate H2S gas levels increase very rapidly after stirring starts, and mostly decline to baseline levels within 30 min post start of stirring. There were, however, circumstances where gas levels remained high and only started to decline once the stirrer had stopped. H2S gas levels at all farms, at all positions measured were consistently below 10 ppm within 30 min of the stirrer being stopped. The current data highlight areas of the farm and ways of working that have the potential for workers and others to be at risk of exposure to toxic slurry gases. The area should be left to ventilate naturally for at least 30 min after the stirrer has been stopped before re-entering buildings. Influencing the design of stirring equipment and future slurry stores would likely reduce the risk of worker exposure to slurry gases.

Indoor and ambient black carbon and fine particulate matter associations with blood biomarkers in COPD patients.

BACKGROUND: Systemic inflammation contributes to cardiovascular risk and chronic obstructive pulmonary disease (COPD) pathophysiology. Associations between systemic inflammation and exposure to ambient fine particulate matter (PM ≤ 2.5 µm diameter; PM2.5), and black carbon (BC), a PM2.5 component attributable to traffic and other sources of combustion, infiltrating indoors are not well described. METHODS: Between 2012 and 2017, COPD patients completed in-home air sampling over one-week intervals, up to four times (seasonally), followed by measurement of plasma biomarkers of systemic inflammation, C-reactive protein (CRP) and interleukin-6 (IL-6), and endothelial activation, soluble vascular adhesion molecule-1 (sVCAM-1). Ambient PM2.5, BC and sulfur were measured at a central site. The ratio of indoor/ambient sulfur in PM2.5, a surrogate for fine particle infiltration, was used to estimate indoor BC and PM2.5 of ambient origin. Linear mixed effects regression with a random intercept for each participant was used to assess associations between indoor and indoor of ambient origin PM2.5 and BC with each biomarker. RESULTS: 144 participants resulting in 482 observations were included in the analysis. There were significant positive associations between indoor BC and indoor BC of ambient origin with CRP [%-increase per interquartile range (IQR);95 % CI (13.2 %;5.2-21.8 and 11.4 %;1.7-22.1, respectively)]. Associations with indoor PM2.5 and indoor PM2.5 of ambient origin were weaker. There were no associations with IL-6 or sVCAM-1. CONCLUSIONS: In homes of patients with COPD without major sources of combustion, indoor BC is mainly attributable to the infiltration of ambient sources of combustion indoors. Indoor BC of ambient origin is associated with increases in systemic inflammation in patients with COPD, even when staying indoors.

A systematic review on solid fuel combustion exposure and respiratory health in adults in Europe, USA, Canada, Australia and New Zealand.

Epidemiological studies performed in low- and middle-income countries have shown a positive association between solid fuel burning exposure and adverse health effects, including respiratory effects in adults. However, the evidence is less clear in other countries. We performed a systematic review of epidemiological studies conducted in Europe, North America (Canada and USA only), Australia and New Zealand on the association between outdoor and indoor exposure to solid fuel (biomass and coal) combustion and respiratory outcomes in adults. We identified 34 articles. The epidemiological evidence is still limited. Positive associations were found between indoor coal, wood and combined solid fuel combustion exposure and lung cancer risk, although based on a limited number of studies. A significant association was found between indoor solid fuel exposure and COPD risk. Inconsistent results were found considering indoor coal, wood and mixed solid fuel burning exposure and other respiratory outcomes (i.e. lower respiratory infections, upper respiratory infections and other upper respiratory tract diseases, asthma and respiratory symptoms). Inconsistent results were found considering the relationship between the exposure to outdoor wood burning exposure and overall respiratory mortality, asthma, COPD and respiratory symptoms in adults. The available epidemiological evidence between outdoor exposure to residential coal burning and respiratory outcomes suggests an increased risk of adverse respiratory effects. The studies considering the impact of the introduction of measures in order to reduce solid fuel burning on air quality and health showed an improvement in air quality resulting in a reduction of adverse respiratory effects. The identified epidemiological studies have several limitations. Additional and better conducted epidemiological studies are needed to establish whether exposure occurring indoors and outdoors to solid fuel combustion pollutants is associated with adverse respiratory outcomes in adults.

Association of long-term indoor exposure to fine particles with pulmonary effects in Northern Taiwan.

An association between short-term indoor exposure to fine particles (PM2.5) and acute respiratory effects has been reported. It is still unclear whether long-term indoor exposure to PM2.5 is associated with pulmonary events. This study recruited 1023 healthy adult homeworkers to conduct a prospective observational study from 2010 to 2021. Four repeated home visits per year were conducted for each participant to measure 24-hour PM2.5 and peak expiratory flow rate (PEFR) and to collect blood samples for absolute eosinophil count (AEC) and carcinoembryonic antigen (CEA) analysis. Additionally, a questionnaire related to personal characteristics, health status and home characteristics was conducted for each participant. The mixed-effects models showed a significant association of PM2.5 with increased CEA and AEC and decreased % predicted PEFR. No significant association between low-level PM2.5 exposure (10-year mean level < 10 µg/m3) and adverse pulmonary effects was observed. The present study concluded that long-term indoor exposure to PM2.5 at a concentration higher than 10 µg/m3 was associated with adverse pulmonary effects among healthy adult homeworkers.

Household Air Pollution and Respiratory Symptoms a Month Before and During the Stringent COVID-19 Lockdown Levels 5 and 4 in South Africa.

Background: Household air pollution (HAP) is associated with adverse human health impacts. During COVID-19 Lockdown Levels 5 and 4 (the most stringent levels), South Africans remained at home, potentially increasing their exposure to HAP. Objectives: To investigate changes in fuel use behaviours/patterns of use affecting HAP exposure and associated HAP-related respiratory health outcomes during COVID-19 Lockdown Levels 5 and 4. Methods: This was a cross-sectional online and telephonic survey of participants from an existing database. Logistic regression and McNemar's test were used to analyse household-level data. Results: Among 2 505 participants, while electricity was the main energy source for cooking and heating the month before and during Lockdown Levels 5 and 4, some households used less electricity during Lockdown Levels 5 and 4 or switched to "dirty fuels." One third of participants reported presence of environmental tobacco smoke in the home, a source of HAP associated with respiratory illnesses. Prevalence of HAP-related respiratory health outcomes were <10% (except dry cough). Majority of households reported cooking more, cleaning more and spending more time indoors during Lockdown Levels 5 and 4 - potentially exposed to HAP. Conclusion: Should South Africa return to Lockdown Levels 5 or 4, awareness raising about the risks associated with HAP as well as messaging information for prevention of exposure to HAP, including environmental tobacco smoke, and associated adverse health impacts will be necessary.

Association between indoor air pollution and cognitive function among nationally representative sample of middle-aged and older adults in India-A multilevel modelling approach.

We have used a nationally representative sample of middle-aged and older adults in India to study the association between indoor air pollution and cognitive function. Longitudinal aging study in India (LASI) Wave-I data was utilized for this study. A two-level mixed-effects linear regression model was used to study the association between indoor air pollution and cognitive function and interpreted as adjusted beta coefficient (ꞵ) with 95% confidence interval (CI). In total, 56,179 participants aged ≥45 years were included in the analysis. The proportion of participants living in households with indoor air pollution were 30.6% (95%CI: 30.0%-31.3%). After adjusting for all the potential confounders (age, gender, education, region, religion, separate kitchen, socioeconomic status, marital status, residence, smoking, alcohol consumption, body mass index, self-rated health, and sleep problems), participants living in households with indoor air pollution had significant decline in the cognitive function when compared to those living in households without indoor air pollution (ꞵ = -0.57; 95%CI: -0.69 to -0.45). Since the LASI survey is being conducted as a biennial panel survey, assessing the impact of indoor air pollution on cognitive decline using the follow-up data can provide further insights into the pathogenesis of condition.

Association between prenatal exposure to indoor air pollution and autistic-like behaviors among preschool children.

Indoor air pollution is a recognized risk factor for a range of negative health outcomes. This study aimed to investigate the association between maternal prenatal exposure to indoor air pollution and the presence of autistic-like behaviors among preschool children. Data were obtained from the Longhua Child Cohort Study in 2017, in which we enrolled a total of 65 317 preschool children. Associations between maternal exposure to four sources of indoor air pollution (e.g., cooking, environmental tobacco smoke (ETS), mosquito coils, and home decoration) during pregnancy and preschool children's autistic traits were analyzed using multivariate logistic regression. Our results showed that maternal exposure to indoor air pollution from four different sources during pregnancy was associated with the presence of children's autistic-like behaviors. There was dose-response relationship between the accumulative exposure to the four different indoor air pollution sources and the risk of autistic-like behaviors. Furthermore, we found a significant additive interaction between prenatal exposure to both cooking and mosquito coil incense on the risk of autistic-like behaviors. Maternal prenatal exposure to the indoor air pollution from four sources might increase with the risk of autistic-like behaviors being present among preschool children, with an additive interaction effect between some pollution sources.

Indoor Air Pollution (IAP) Traceable to Household Fuel Consumption and its Impact on Health.

Energy is an essential and obligatory prerequisite of life. Indoor air pollution is one of the biggest environmental problems in the world being specifically concentrated in resource limited settings. Inspite of the availability of cleaner fuel technologies, people in resource limited setting still depend on traditional fuel to meet their basic needs resulting even in premature deaths. In Nepal people in rural areas are the pre-dominant users of biomass fuel, there is limited research focusing on rural areas particularly; women as they spend most of their time in kitchen. Reports were extensively searched for literature using preset keywords in English language peer-reviewed journals databases PubMed and Google Scholar published between the years 2005 to 2020. Citation details were examined, titles and abstracts screened for eligibility and if relevant, full text was also reviewed in greater detail. Findings were then presented primarily under two bold themes: Household fuel consumption: existing theories and evidence; and health impact of indoor air pollution. Several health effects were reported of indoor air pollution including respiratory illnesses, cardiovascular diseases, cancer, endocrine system disruption and pregnancy complications. These exposures almost double the health risks predominantly among children and women of rural communities as they are directly involved in household activities causing air pollution. Based on our review of evidence, women and children of rural households were the major victims. Further, determinants of household fuel consumption and health effects should be considered while formulating policies in regard to promoting accessibility of clean fuels and reducing household air pollutants.

Parental tobacco and indoor secondhand smoking exposure and the risk of offspring under-five mortality in low- and middle-income countries.

Children are vulnerable to exposure of secondhand smoking (SHS) which is a major preventable cause of disease and death. This study aimed to investigate the association between parental tobacco use or SHS exposure, respectively, and under-five mortality. Data were obtained from the nationally representative and population-based Demographic and Health Surveys in low- and middle-income countries (LMICs) between 2000 and 2018. Cox proportional hazard regression models with complex survey design were conducted to examine the adjusted associations between parental smoking and SHS exposure and child under-five mortality. In the pooled analysis of parental smoking, 437 322 children were included. Compared with children whose parents are not smoking, those whose father or both parents smoked any form of tobacco had higher risks of mortality (hazard ratio [HR] = 1.08, 95% confidence interval [CI] = 1.03-1.13; HR = 1.18, 95% CI = 1.06-1.32, respectively). In addition, parental using smokeless tobacco, smoking tobacco, and using smokeless tobacco and smoking tobacco simultaneously was significantly associated with child under-five mortality (HR = 1.07, 95% CI = 1.01-1.12; HR = 1.12, 95%CI = 1.04-1.21; and HR = 1.17, 95%CI = 1.06-1.30, respectively). In the pooled analysis of SHS exposure, 605 442 children were included, and weekly and daily SHS exposure were significantly associated with child under-five mortality (HR = 1.11, 95% CI = 1.03-1.20, and HR = 1.10, 95% CI = 1.06-1.15, respectively). The results were robust in most stratification analyses and sensitivity analyses. Parental tobacco use and indoor SHS exposure were associated with increased risk of under-five mortality in LMICs. Comprehensive tobacco control programs should be considered by policymakers in LMICs to promote smoke-free environments for children.

Efficacy and cost-effectiveness of a community-based smoke-free-home intervention with or without indoor-air-quality feedback in Bangladesh (MCLASS II): a three-arm, cluster-randomised, controlled trial.

BACKGROUND: Exposure to second-hand smoke from tobacco is a major contributor to global morbidity and mortality. We aimed to evaluate the efficacy and cost-effectiveness of a community-based smoke-free-home intervention, with or without indoor-air-quality feedback, in reducing second-hand-smoke exposure in homes in Bangladesh. METHODS: We did a three-arm, cluster-randomised, controlled trial in Dhaka, Bangladesh, and randomly assigned (1:1:1) mosques and consenting households from their congregations to a smoke-free-home intervention plus indoor-air-quality feedback, smoke-free-home intervention only, or usual services. Households were eligible if they had at least one resident attending one of the participating mosques, at least one adult resident (age 18 years or older) who smoked cigarettes or other forms of smoked tobacco (eg, bidi, waterpipe) regularly (on at least 25 days per month), and at least one non-smoking resident of any age. The smoke-free-home intervention consisted of weekly health messages delivered within an Islamic discourse by religious leaders at mosques over 12 weeks. Indoor-air-quality feedback comprised providing households with feedback on their indoor air quality measured over 24 h. Households in the usual services group received no intervention. Masking of participants and mosque leaders was not possible. The primary outcome was the 24-h mean household airborne fine particulate matter (<2·5 microns in diameter [PM2·5]) concentration (a marker of second-hand smoke) at 12 months after randomisation. Cost-effectiveness was estimated using incremental cost-effectiveness ratios (ICERs). This trial is registered with ISRCTN, 49975452. FINDINGS: Between April 11 and Aug 2, 2018, we enrolled 1801 households from 45 mosques. 640 households (35·5%) were assigned to the smoke-free-home intervention plus indoor-air-quality feedback group, 560 (31·1%) to the smoke-free-home intervention only group, and 601 (33·4%) to the usual services group. At 12 months, the adjusted mean difference in household mean 24-h PM2·5 concentration was -1·0 µg/m3 (95% CI -12·8 to 10·9, p=0·88) for the smoke-free-home intervention plus indoor-air-quality feedback group versus the usual services group, 5·0 µg/m3 (-7·9 to 18·0, p=0·45) for the smoke-free-home intervention only group versus the usual services group, and -6·0 µg/m3 (-18·3 to 6·3, p=0·34) for the smoke-free-home intervention plus indoor-air-quality feedback group versus the smoke-free-home intervention only group. The ICER for the smoke-free-home intervention plus indoor-air-quality feedback versus usual services was US$653 per quality-adjusted life-year (QALY) gained, which was more than the upper limit of the Bangladesh willingness-to-pay threshold of $427 per QALY. INTERPRETATION: The smoke-free-home intervention, with or without indoor-air-quality feedback, was neither effective nor cost-effective in reducing household second-hand-smoke exposure compared with usual services. These interventions are therefore not recommended for Bangladesh. FUNDING: Medical Research Council UK. TRANSLATION: For the Bengali translation of the abstract see Supplementary Materials section.

Environmental Determinants of Coronavirus Disease 2019 (COVID-19).

PURPOSE FOR REVIEW: Since the coronavirus SARS-CoV-2 outbreak in China in late 2019 turned into a global pandemic, numerous studies have reported associations between environmental factors, such as weather conditions and a range of air pollutants (particulate matter, nitrogen dioxide, ozone, etc.) and the first wave of COVID-19 cases. This review aims to offer a critical assessment of the role of environmental exposure risk factors on SARS-CoV-2 infections and COVID-19 disease severity. RECENT FINDINGS: In this review, we provide a critical assessment of COVID-19 risk factors, identify gaps in our knowledge (e.g., indoor air pollution), and discuss methodological challenges of association and causation and the impact lockdowns had on air quality. In addition, we will draw attention to ethnic and socioeconomic factors driving viral transmission related to COVID-19. The complex role angiotensin-converting enzyme 2 (ACE2) plays in COVID-19 and future promising avenues of research are discussed. To demonstrate causality, we stress the need for future epidemiologic studies integrating personal air pollution exposures, detailed clinical COVID-19 data, and a range of socioeconomic factors, as well as in vitro and in vivo mechanistic studies.

The home environment in a nationwide sample of multi-family buildings in Sweden: associations with ocular, nasal, throat and dermal symptoms, headache, and fatigue among adults.

Risk factors at home for ocular, nasal, throat and dermal symptoms, headache, and fatigue were studied in a nationwide questionnaire survey in Sweden, the BETSI study in 2006. Totally, 5775 adults from a stratified random sample of multi-family buildings participated. Associations between home environment factors and weekly symptoms were analyzed by multi-level logistic regression. In total, 8.3% had ocular symptoms; 11.9% nasal symptoms; 7.1% throat symptoms; 11.9% dermal symptoms; 8.5% headache and 23.1% fatigue. Subjects in colder climate zones had more mucosal and throat symptoms but less fatigue and ocular symptoms. Rented apartments had poorer indoor environment than self-owned apartments. Those living in buildings constructed from 1961 to 1985 had most symptoms. Building dampness, mold and mold odor were risk factors, especially headache and ocular symptoms. Lack of mechanical ventilation system was another risk factor, especially for headache. Environmental tobacco smoke (ETS), electric radiators, and crowdedness were other risk factors. Oiled wooden floors, recent indoor painting, and new floor materials were negatively associated with symptoms. In conclusion, building dampness, mold, poor ventilation conditions, crowdedness, ETS, and emissions from electric radiators in apartments in Sweden can increase the risk of ocular, nasal, throat and dermal symptoms, headache, and fatigue.

Modeling approaches and performance for estimating personal exposure to household air pollution: A case study in Kenya.

This study assessed the performance of modeling approaches to estimate personal exposure in Kenyan homes where cooking fuel combustion contributes substantially to household air pollution (HAP). We measured emissions (PM2.5 , black carbon, CO); household air pollution (PM2.5 , CO); personal exposure (PM2.5 , CO); stove use; and behavioral, socioeconomic, and household environmental characteristics (eg, ventilation and kitchen volume). We then applied various modeling approaches: a single-zone model; indirect exposure models, which combine person-location and area-level measurements; and predictive statistical models, including standard linear regression and ensemble machine learning approaches based on a set of predictors such as fuel type, room volume, and others. The single-zone model was reasonably well-correlated with measured kitchen concentrations of PM2.5 (R2  = 0.45) and CO (R2  = 0.45), but lacked precision. The best performing regression model used a combination of survey-based data and physical measurements (R2  = 0.76) and a root mean-squared error of 85 µg/m3 , and the survey-only-based regression model was able to predict PM2.5 exposures with an R2 of 0.51. Of the machine learning algorithms evaluated, extreme gradient boosting performed best, with an R2 of 0.57 and RMSE of 98 µg/m3 .

Real-time molecular characterization of air pollutants in a Hong Kong residence: Implication of indoor source emissions and heterogeneous chemistry.

Due to the high health risks associated with indoor air pollutants and long-term exposure, indoor air quality has received increasing attention. In this study, we put emphasis on the molecular composition, source emissions, and chemical aging of air pollutants in a residence with designed activities mimicking ordinary Hong Kong homes. More than 150 air pollutants were detected at molecular level, 87 of which were quantified at a time resolution of not less than 1 hour. The indoor-to-outdoor ratios were higher than 1 for most of the primary air pollutants, due to emissions of indoor activities and indoor backgrounds (especially for aldehydes). In contrast, many secondary air pollutants exhibited higher concentrations in outdoor air. Painting ranked first in aldehyde emissions, which also caused great enhancement of aromatics. Incense burning had the highest emissions of particle-phase organics, with vanillic acid and syringic acid as markers. The other noteworthy fingerprints enabled by online measurements included linoleic acid, cholesterol, and oleic acid for cooking, 2,5-dimethylfuran, stigmasterol, iso-/anteiso-alkanes, and fructose isomers for smoking, C28 -C34 even n-alkanes for candle burning, and monoterpenes for the use of air freshener, cleaning agents, and camphor oil. We showed clear evidence of chemical aging of cooking emissions, giving a hint of indoor heterogeneous chemistry. This study highlights the value of organic molecules measured at high time resolutions in enhancing our knowledge on indoor air quality.

Health risk assessment of volatile organic compounds at daycare facilities.

Children are particularly vulnerable to many classes of the volatile organic compounds (VOCs) detected in indoor environments. The negative health impacts associated with chronic and acute exposures of the VOCs might lead to health issues such as genetic damage, cancer, and disorder of nervous systems. In this study, 40 VOCs including aldehydes and ketones, aliphatic hydrocarbons, esters, aromatic hydrocarbons, cyclic terpenes, alcohols, and glycol ethers were identified and qualified in different locations at the University of Missouri (MU) Child Development Laboratory (CDL) in Columbia, Missouri. Our results suggested that the concentrations of the VOCs varied significantly among classrooms, hallways, and playground. The VOCs emitted from personal care and cleaning products had the highest indoor levels (2-ethylhexanol-1, 3-carene, homomenthyl salicylate with mean concentration of 5.15 µg/m3 , 1.57 µg/m3 , and 1.47 µg/m3 , respectively). A cancer risk assessment was conducted, and none of the 95th percentile dose estimates exceeded the age-specific no significant risk levels (NSRL) in all classrooms. Dimensionless toxicity index scores were calculated for all VOCs using a novel web-based framework called Toxicological Prioritization Index (ToxPi), which integrates multiple sources of toxicity data. According to the method, homomenthyl salicylate, benzothiazole, 2-ethylhexyl salicylate, hexadecane, and tridecane exhibited diverse toxicity profiles and ranked as the five most toxic indoor VOCs. The findings of this study provide critical information for policy makers and early education professionals to mitigate the potentially negative health impacts of indoor VOCs in the childcare facilities.

The effects of household solid fuel use on self-reported and performance-based physical functioning in middle-aged and older Chinese populations: A cross-sectional study.

BACKGROUND: Physical limitation, which has been linked to outdoor air pollution exposure in previous studies, is a risk factor for disability and even for premature death. Although people often spend more time indoors, the relationship between indoor air pollution and physical function has not been fully explored. METHODS: The associations of household fuel types with self-reported and performance-based physical functioning were tested on a total of 12,458 participants in the China Health and Retirement Longitudinal Study (CHARL), using generalized linear models and logistic regression models. Additionally, subgroup analyses according to smoking status and number of chronic diseases, were performed regarding these associations. RESULTS: Our results revealed that after adjusting for potential confounds, solid fuel use in cooking showed -0.08 (-0.13, -0.04) and -0.15 (-0.23, -0.06) declines in self-reported and performance-based physical functioning scores (higher scores means fewer physical limitations), when compared with cleaner groups, respectively. Considering these outcomes as binary variables, the ORs (95% CIs) for abnormal self-reported and performance-based physical functioning in the solid fuel cooking group were 1.226 (1.053-1.427) and 1.194 (1.072-1.330), respectively. No significant association between heating fuel use and physical functioning was observed. Additionally, no modification effect of smoking status and the number of chronic diseases on the association between cooking fuel use and performance-based physical functioning was observed (P > 0.05). CONCLUSION: Our findings suggested that solid cooking fuel use may be associated with self-reported and performance-based physical functioning decline of middle-aged and elder Chinese populations.