Fine particle air pollution and mortality: importance of specific sources and chemical species.

BACKGROUND: While exposure to ambient fine particles <2.5 µm in aerodynamic diameter (PM2.5) has well-established health effects, there is limited quantitative evidence that links specific sources of PM2.5 with those effects. This study was designed to examine the risks of exposure to chemical species and source-specific PM2.5 mass on mortality in Seoul, Korea, a highly populated city. METHODS: We compare daily mortality counts with PM2.5 chemical speciation data collected every 3 days, as well as nine sources of PM2.5 mass resolved by a positive matrix factorization receptor model, from March 2003 through November 2007. A Poisson generalized linear model incorporating natural splines was used to evaluate associations of PM2.5 chemical species and sources with mortality. RESULTS: PM2.5 mass and several chemical species were associated with mortality. Organic carbon, elemental carbon, and lead were associated with mortality outcomes when using multipollutant models adjusted for other chemical species levels. Source-apportioned PM2.5 derived from mobile sources (ie, gasoline and diesel emissions) and biomass burning was associated with respiratory mortality and cardiovascular mortality, respectively. There were moderate associations of industry and of roadway emissions with cardiovascular mortality. CONCLUSIONS: Local combustion sources may be particularly important contributors to PM2.5, leading to adverse health effects.

Association between environmental tobacco smoke exposure of children and parental socioeconomic status: a cross-sectional study in Korea.

INTRODUCTION: It has been reported that most environmental tobacco smoke (ETS) exposure of children occurs at home, and lower parental socioeconomic status (SES) increases the risk of this exposure. We estimated the independent and interactive effects of parental SES and residential area SES on ETS exposure of children at home. METHODS: We evaluated whether ETS exposure was associated with parental SES by entering data from 7,059 school-aged children in Korea into fixed effects models. The empirical model, including the interaction variable of the level of deprivation of each residential area, was fitted with parental SES. RESULTS: After adjustment for possible confounding variables, low paternal education (odds ratio [OR], 1.81; 95% CI, 1.30-2.54) and highly deprived areas (OR, 1.34; 95% CI, 1.06-1.69) were significantly associated with the ETS exposure of children, especially among children whose fathers had <12 years of education and lived in the most deprived area (OR, 2.04; 95% CI, 1.04-4.02). CONCLUSIONS: Our findings suggest that the SES of residential areas may influence the ETS exposure of children directly, as well as interactively with parental SES, in Korea. Findings from this study will help inform policy decision makers that intervention to promote smoking cessation should consider not only the SES of individuals but also that of residential areas.

Effect of environmental tobacco smoke on atopic dermatitis among children in Korea.

The prevalence of atopic dermatitis is increasing in many countries. Several factors are known to be associated with childhood atopic dermatitis. Environmental tobacco smoke (ETS) is one of the most common indoor pollutants, and children are more vulnerable to ETS exposure than adults are. In this study, the possible association of ETS with atopic dermatitis was evaluated in 7030 individuals aged 6-13 years who participated in the Children's Health and Environment Research study. In addition, predictive factors, such as the allergic history of the parents, children's immunoglobulin E levels and children's history of rhinitis and its association with dermatitis, were assessed. After adjustment for possible confounding variables, atopic dermatitis was found to be highly correlated with ETS, especially among children whose mothers had smoked during pregnancy and/or in the first year after birth (OR=2.06, 95% CI: 1.01-4.22). In conclusion, our results show that childhood exposure to ETS is a major risk factor for atopic dermatitis.

Does area level socioeconomic status modify the effects of PM(10) on preterm delivery?

BACKGROUND: Air pollution has been one of the focal points for investigations of maternal health and birth, and an association has been found between air pollution and birth outcomes. Some individual-level risk factors of mothers have been identified as strong predictors of preterm delivery (PTD). Recent literature has shown that the neighborhood environment of the mother and child has an independent influence on birth outcomes that was not explained by individual-level risk factors. OBJECTIVE: This study explored the effects of maternal exposure to particulate air pollution (PM(10)) and its relationship to the probability of preterm delivery (PTD) in Seoul, Korea. Our hypothesis was that PM(10) increased the probability of PTD, and that the area level socioeconomic status (SES), measured by monthly average household income, modified the PM(10) effects on PTD after controlling for individual-level risk factors such as individual-level SES. DATA AND METHOD: Birth data from the Korean National Statistics Office consisted of records on 433,173 singleton births in the years 2000-2003, and included individual characteristics. Area-level characteristics were also controlled for in 25 administrative regions in Seoul. Maternal exposure to PM(10) was calculated at an individual level for each trimester using information from monitoring sites in residential areas. Hourly data on PM(10) for 1999-2003 were acquired from the National Institute of Environment Research. Birth outcome was dichotomously coded: term birth (gestation > or =37 weeks) or PTD (gestation <37 weeks). For multilevel analysis, we conducted a hierarchical logistic regression with a random intercept for each administrative area to account for the hierarchical nature of the data. RESULTS: We found that area-level SES modified the PM(10) effects on PTD, specifically among those who were in low SES areas. Results of multilevel analyses showed that an increase in PM(10) by 10 microg/m(3) led to a statistically significant increase in the probability of PTD [3.12% (95% CI, 0.17-6.15)] during the 2nd trimester in the low-income group. Analyses using the stratified population found a 3.4% increase (95% CI, 0.31-6.58) in the probability of PTD during the 2nd trimester in areas with low income. CONCLUSION: Mothers exposed to higher PM(10) in Seoul, Korea, had a higher probability of PTD. Individual-level characteristics had different effects on the probability of PTD depending on the area-level SES. Area-level SES modified the effect of PM(10) concentration on PTD.

Seasonal effect of PM(10) concentrations on mortality and morbidity in Seoul, Korea: a temperature-matched case-crossover analysis.

BACKGROUND: Explorations of interactions between air pollution and seasonal changes have represented one approach in examining the consequences of global warming. However, only a few studies have focused on evaluating the effects of seasonal air pollution using data on both morbidity and mortality in Asia. METHOD: We examined the associations between PM(10) concentrations and mortality and hospital admissions in Seoul, Korea for the periods 2000-2006 and 2001-2006. We employed a temperature-matched case-crossover design, where reference periods matched case days in regard to temperature (same rounded to degrees celsius ( degrees C)), month, and year. RESULTS: A total of 238,826 deaths were identified, along with 98,570 and 93,553 inpatient admissions for cardiovascular and respiratory diseases, respectively. We found that the association with PM(10) and mortality/morbidity increased during the summer. During the study period, 10microg/m(3) increase in PM(10) was associated with the increase in mortality by 0.28% (95% confidence interval: 0.12, 0.44), 0.51% (0.19, 0.83), and 0.59% (-0.08, 1.26) for non-accidental, cardiovascular, and respiratory causes. 10microg/m(3) increase in PM(10) was also associated with increase in hospitalization from cardiovascular and respiratory causes by 0.77% (0.53, 1.01) and 1.19% (0.94, 1.44). In the summer, the increase in mortality and hospitalization was 0.57% (0.20, 0.93), 0.64% (-0.10, 1.38), 0.50% (-1.02, 2.05), 1.52% (0.89, 2.16), and 1.55% (0.87, 2.22). CONCLUSIONS: This study provides evidence that the effect of PM(10) on mortality and morbidity varies with season and increases during the summer season.

The role of differences in individual and community attributes in perceived air quality.

Most epidemiological studies on the adverse effects of air pollution on health have focused on scientific measurements of air quality provided by monitoring stations. However, many studies have indicated that self-reported health status, such as disease severity and depressive symptoms, are associated with perceived air pollution rather than measured air pollution. The main goal of this study was to investigate social factors that may affect perceived local air quality using a multilevel analysis among a Korean population. We used the Seoul Citizens Health Indicator Survey (SCHIS III) and five air pollutants. The total study population was 16,041. We considered individual-level and community-level variables that may affect perceived air quality, such as the percentage of college-educated individuals aged >20 years, satisfaction with public transportation, and the percentage of individuals below the poverty line. Measured air quality showed a negative or neutral relationship with perceived air quality. We found that the degree of perceived air pollution was associated with younger age (20-34 years; OR=1.40, 95% CI=1.18-1.65), married and divorced/separated/widowed people, a higher level of education (>17 years; OR=1.67, 95% CI=1.30-2.15), and lower household income. Communities that were more economically deprived were associated with poor perceived air quality. Differences in individual and community characteristics affected perceived air quality. Perception is a key factor influencing the public acceptance of environmental policy. This study may help policymakers understand the social distribution of environmental awareness.

Susceptibility to air pollution effects on mortality in Seoul, Korea: a case-crossover analysis of individual-level effect modifiers.

Air pollution's mortality effects may differ by subpopulation; however, few studies have investigated this issue in Asia. We investigated susceptibility to air pollutants on total, cardiovascular, and respiratory mortality in Seoul, Korea for the period 2000-2007. We applied time-stratified case-crossover analysis, which allows direct modeling of interaction terms, to estimate susceptibility based on sex, age, education, marital status, and occupation. An interquartile range increase in pollution was associated with odds ratios of 0.94 (95% confidence interval, 0.25-1.62), 2.27 (1.03-3.53), 1.94 (0.80-3.09), and 2.21 (1.00-3.43) for total mortality and 1.95 (0.64-3.27), 4.82 (2.18-7.54), 3.64 (1.46-5.87), and 4.32 (1.77-6.92) for cardiovascular mortality for PM(10), nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), and carbon monoxide (CO), respectively. Ozone effect estimates were positive, but not statistically significant. Results indicate that some populations are more susceptible than others. For total or cardiovascular mortality, associations were higher for males, those 65-74 years, and those with no education or manual occupation for some pollutants. For example, the odds ratio for SO(2) and cardiovascular mortality was 1.19 (1.03-1.37) times higher for those with manual occupations than professional occupations. Our findings provide evidence that some populations are more susceptible to the effects of air pollution than others, which has implications for public policy and risk assessment for susceptible subpopulations.