Personal exposure to aldehydes and potential health risks among schoolchildren in the city.

Schoolchildren are sensitive to airborne aldehyde exposures. The knowledge regarding inhalation exposure to aldehydes and the factors influencing exposure in schoolchildren is limited. This study aimed to assess the variability and potential health risks of exposure to aldehydes (including formaldehyde) in schoolchildren. The important factors affecting personal exposure to aldehydes were also explored. Forty schoolchildren were recruited from the urban and suburban areas of Taiwan for aldehyde samplings and questionnaire surveys. Personal and indoor home samples of aldehydes were collected simultaneously during warm and cold seasons. We also identified the potential variables associated with aldehyde exposure based on the participant's responses to the questionnaires using mixed-effects models. The dominant three abundant aldehydes identified in personal exposure samples were formaldehyde (geometric mean, GM = 12.2 µg/m3), acetaldehyde (GM = 5.53 µg/m3), and hexaldehyde (GM = 8.79 µg/m3), accounting for approximately 80% of the total selected aldehydes. Higher personal exposure to aldehydes was observed during the warm season. Moreover, the within-subject variance was predominant, accounting for 66.6 to > 99.9% of the total variance in exposure. Schoolchildren had a high probability of overexposure to formaldehyde and acrolein, which resulted in an incremental lifetime cancer risk of 1.59 × 10-4 (95th percentile = 4.64 × 10-4). Season, location, household refurbishment, and indoor ventilation variables were significantly associated with personal exposure to aldehydes. The results can improve our understanding of aldehyde exposure among schoolchildren to propose mitigation strategies. These findings may be applied to further epidemiological studies.

Impacts of COVID-19's restriction measures on personal exposure to VOCs and aldehydes in Taipei City.

The Coronavirus Disease 2019 (COVID-19) pandemic provided an unprecedented natural experiment, that allowed us to investigate the impacts of different restrictive measures on personal exposure to specific volatile organic compounds (VOCs) and aldehydes and resulting health risks in the city. Ambient concentrations of the criteria air pollutants were also evaluated. Passive sampling for VOCs and aldehydes was conducted for graduate students and ambient air in Taipei, Taiwan, during the Level 3 warning (strict control measures) and Level 2 alert (loosened control measures) of the COVID-19 pandemic in 2021-2022. Information on the daily activities of participants and on-road vehicle counts nearby the stationary sampling site during the sampling campaigns were recorded. Generalized estimating equations (GEE) with adjusted meteorological and seasonal variables were used to estimate the effects of control measures on average personal exposures to the selected air pollutants. Our results showed that ambient CO and NO2 concentrations in relation to on-road transportation emissions were significantly reduced, which led to an increase in ambient O3 concentrations. Exposure to specific VOCs (benzene, methyl tert-butyl ether (MTBE), xylene, ethylbenzene, and 1,3-butadiene) associated with automobile emissions were remarkably decreased by ~40-80 % during the Level 3 warning, resulting in 42 % and 50 % reductions of total incremental lifetime cancer risk (ILCR) and hazard index (HI), respectively, compared with the Level 2 alert. In contrast, the exposure concentration and calculated health risks in the selected population for formaldehyde increased by ~25 % on average during the Level 3 warning. Our study improves knowledge of the influence of a series of anti-COVID-19 measures on personal exposure to specific VOCs and aldehydes and its mitigations.

Exposure variability and determining factors of urinary metals for schoolchildren in Taiwan.

Urinary heavy metal levels in schoolchildren vary greatly over time, and research on the determinant variables explaining variance components in urinary metal exposure is limited. This study assessed metal concentrations and variability in the urine of schoolchildren and explored their important determining factors. We collected spot urine samples from schoolchildren (n = 321) living in urban, suburban, and rural areas during the warm and cold seasons. The toxic (As, Cd, Ni, Cd, and Pb) and essential (Co, Cu, Mo, and V) elements of urine samples were analyzed by inductively coupled plasma mass spectrometry. We assessed the within- and between-subject variability in urinary metal concentrations, calculated the "probability of overexposure (θ)," compared with the reference values. We evaluated the spatiotemporal and biological factors that determine average exposure by using a mixed-effects model. The within-subject variance accounting for 63.8%-95.4% of the total variance in exposures was predominant for selected urinary metals. Urinary As levels (subject-specific mean = 69.0 µg/g creatinine) in schoolchildren were remarkably high and presented ∼99.9% of θ. After adjusting for the selected variables, we found that urban schoolchildren had significantly higher urinary metal levels (As, Cr, Co, and Ni) than suburban and rural schoolchildren. The urinary levels of most metals (except for Cu and Pb) increased during the cold season. Girls had higher urinary Cr, Co, Cu, Ni, and Pb levels than boys. Body mass index and urinary creatinine could also affect urinary metal levels. Those variables explained 15.8% (Pb), 11.6% (Cr), and 6.5% (Cd) of total variance in urinary concentrations. The repeated measurements of spot urine samples across seasons in individuals for long-term exposure estimates of metals were suggested. This biomonitoring survey of a large number of urine samples provided useful information on toxic metals and on the important determinants of exposure in schoolchildren.

Household airborne endotoxin associated with asthma and allergy in elementary school-age children: a case-control study in Kaohsiung, Taiwan.

To evaluate the association between the presence of asthma and allergy, and airborne endotoxin in homes of school-age children in Kaohsiung City, Taiwan, with a case-control study design by matching the age and class exposure. Data collection of home visits included an interviewer-administered questionnaire and air sampling of participants' homes for endotoxin, bacteria, and fungi, as well as temperature and relative humidity measurements. Endotoxin was detected in all air samples with a median value of 0.67 EU m-3. In the adjusted logistic regression model, household airborne endotoxin was associated with higher prevalence of asthma and allergy; OR = 4.88 (95% CI 1.16-20.55) for Q3 (between 0.67 and 1.97 EU m -3) vs. Q1 (< 0.31 EU m -3), with statistical significance. Airborne fungi were associated with higher prevalence of asthma and allergy; OR = 4.47 (95% CI 1.13-17.69) for Q3 (between 314 and 699 CFU m -3) vs. Q1 (< 159 CFU m -3) in adjusted logistic regression models. Airborne endotoxin and fungi were significantly associated with children's asthma and allergy.

Indoor ozone and particulate matter modify the association between airborne endotoxin and schoolchildren's lung function.

BACKGROUND: To date, the effect of household airborne pollutants on the association between airborne endotoxin and lung function of schoolchildren is unknown. OBJECTIVES: The objective of this study is to evaluate whether indoor air pollutants such as carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), particulate matter with aerodynamic diameter <10 and 2.5 µm (PM10, PM2.5) can modify the association between airborne endotoxin and school children's lung function in a heavy industrial city in Taiwan. METHODS: We recruited 120 elementary school-age children in Kaohsiung City, Taiwan. Aerosol samples were collected on a filter membrane for 24 h period and then analyzed for endotoxin. Air pollutants were measured for 24 h in living rooms while school children's lung function was measured. The modification of air pollutants on the relationship between airborne endotoxin and children's lung function was estimated after adjusting the gender, age, height, weight, and case-control status. RESULTS: We found that both O3 and PM10 concentrations significantly modified the relationships between airborne endotoxin and school children's lung function. Among children living in homes with O3 ≥ 0.01 ppm or PM10 ≥ 62 µg/m3, airborne endotoxin was negatively associated with lung functions, whereas among those living in homes with O3 < 0.01 ppm or PM10 < 62 µg/m3, airborne endotoxin was positively associated with lung functions. CONCLUSIONS: The indoor air pollutant concentration of O3 and PM10 modifies the association between airborne endotoxin and school children's lung function.

Jumping on the bed and associated increases of PM10, PM2.5, PM1, airborne endotoxin, bacteria, and fungi concentrations.

Jumping on the bed is a favorite behavior of children; however, no study has investigated the increased air pollutants resulting from jumping on the bed. Therefore, we aimed to investigate the elevated concentrations of particulate matter (PM) and bioaerosols from jumping on the bed and making the bed. Simulation of jumping on the bed and making the bed was performed at sixty schoolchildren's houses in Taiwan. PM10, PM2.5, PM1 (PM with aerodynamic diameter less than 10, 2.5, and 1 µm, respectively) and airborne bacteria, fungi and endotoxin concentrations were simultaneously measured over simulation and background periods. Our results show the increase of PM10, PM2.5, PM1, airborne bacteria and fungi through the behavior of jumping on the bed (by 414 µg m-3, 353 µg m-3, 349 µg m-3, 6569 CFU m-3 and 978 CFU m-3, respectively). When making the bed, the PM10, PM2.5, PM1, airborne bacteria and fungi also significantly increased by 4.69 µg m-3, 4.09 µg m-3, 4.15 µg m-3, 8569 CFU m-3, and 779 CFU m-3, respectively. Airborne endotoxin concentrations significantly increased by 21.76 EU m-3 following jumping on the bed and making the bed. Moreover, when jumping on the bed, higher PM2.5 and PM1 concentrations in houses with furry pets rather than no furry pets, and less airborne fungi in apartments than in townhouses were found. For making the bed, lower airborne fungi was found in houses using essential oils rather than no essential oils using. The airborne endotoxin concentrations were positively associated with furry pets and smokers in the homes and negatively correlated to the home with window opening with a statistical significance during the periods of jumping on the bed and making the bed. In conclusion, significant increases of PM and bioaerosols during jumping on the bed and making the bed may need to be concerned.

The concentrations of ambient Burkholderia pseudomallei during typhoon season in endemic area of melioidosis in Taiwan.

BACKGROUND: Melioidosis is a severe bacterial infection caused by Burkholderia pseudomallei with a high case-fatality rate. Epidemiological and animal studies show the possibility of inhalation transmission. However, no B. pseudomallei concentrations in ambient air have been researched. Here, we developed a method to quantify ambient B. pseudomallei and then measured concentrations of ambient B. pseudomallei during the typhoon season and the non-typhoon season to determine the factors influencing ambient B. pseudomallei levels. METHODS: We quantified ambient B. pseudomallei by using a filter/real-time qPCR method in the Zoynan Region in Kaohsiung, southern Taiwan. Twenty-four hour samples were collected at a sampling rate of 20 L/min every day from June 11 to December 21, 2012 including during the typhoon season (June to September) and reference season (October to December). RESULTS: We successfully developed a filtration/real-time qPCR method to quantify ambient B. pseudomallei. To our knowledge, this is the first report describing concentrations of ambient B. pseudomallei. Ambient B. pseudomallei were only detected during the typhoon season when compared to the reference season. For the typhoons affecting the Zoynan Region, the positive rates of ambient B. pseudomallei were very high at 80% to 100%. During June to December, rainfall was positively correlated with ambient B. pseudomallei with a statistical significance. Sediment at a nearby pond significantly influenced the concentration of ambient B. pseudomallei. During the typhoon month, the typhoon was positively correlated with ambient B. pseudomallei whereas wind speed was reversely correlated with ambient B. pseudomallei. CONCLUSIONS: Our data suggest the possibility of transmission of B. pseudomallei via inhalation during the typhoon season.