Exposure to volatile organic compounds and health risks among residents in an area affected by a petrochemical complex in Rayong, Thailand.

In Thailand, there is a growing concern regarding the possible effects of air pollution on the health of residents living near a petrochemical complex in Map Ta Phut Industrial Estate (MTPIE), Rayong Province, Thailand. We studied exposure to selected volatile organic compounds (VOCs) in Map Ta Phut and the association between residing near the petrochemical complex and respiratory ailments. We carried out a population-based cross-sectional study, utilizing health data regarding respiratory problems among adults collected as part of a Health Effects of Air Pollution study of residents living in Map Ta Phut Municipality, Thailand, using a standardized questionnaire. The distance from the subject's residence to the center of the MTPIE was mapped using a geographical information system (GIS). A total of 15,441 adults aged > or = 13 years who lived in Map Ta Phut Municipality for at least 1 year were included in the study. Multiple logistic regression models were used to examine the relationship between the distance between the subject's residence and the MTPIE and the presence of the respiratory problems during the previous 12 months. A 5 km distance was chosen as the maximum study radius. Volatile organic compounds were observed higher concentrations at sites downwind from the MTPIE, and closer to the MTPIE. Study subjects who lived closer to the MTPIE reported an odor more frequently than subjects who lived farther from the MTPIE. Living closer to the MTPIE was associated with more acute respiratory problems, but not more chronic respiratory problems than living farther from the MTPIE. Adults aged > or = 40 years were more likely to have respiratory symptoms and eye irritation than those aged < 40 years. Females were more likely to have dyspnea, wheezing and upper respiratory symptoms than males. Living near the MTPIE for more than 5 years was associated with an increased risk of wheezing and upper respiratory symptoms.

Part 5. Public health and air pollution in Asia (PAPA): a combined analysis of four studies of air pollution and mortality.

BACKGROUND: In recent years, Asia has experienced rapid economic growth and a deteriorating environment caused by the increasing use of fossil fuels. Although the deleterious effects of air pollution from fossil-fuel combustion have been demonstrated in many Western nations, few comparable studies have been conducted in Asia. Time-series studies of daily mortality in Asian cities can contribute important new information to the existing body of knowledge about air pollution and health. Not only can these studies verify important health effects of air pollution in local regions in Asia, they can also help determine the relevance of existing air pollution studies to mortality and morbidity for policymaking and environmental controls. In addition, the studies can help identify factors that might modify associations between air pollution and health effects in various populations and environmental conditions. Collaborative multicity studies in Asia-especially when designed, conducted, and analyzed using a common protocol-will provide more robust air pollution effect estimates for the region as well as relevant, supportable estimates of local adverse health effects needed by environmental and public-health policymakers. SPECIFIC OBJECTIVES: The Public Health and Air Pollution in Asia (PAPA*) project, sponsored by the Health Effects Institute, consisted of four studies designed to assess the effects of air pollution on mortality in four large Asian cities, namely Bangkok, in Thailand, and Hong Kong, Shanghai, and Wuhan, in China. In the PAPA project, a Common Protocol was developed based on methods developed and tested in NMMAPS, APHEA, and time-series studies in the literature to help ensure that the four studies could be compared with each other and with previous studies by following an established protocol. The Common Protocol (found at the end of this volume) is a set of prescriptive instructions developed for the studies and used by the investigators in each city. It is flexible enough to allow for adjustments in methods to optimize the fit of health-effects models to each city's data set. It provides the basis for generating reproducible results in each city and for meta-estimates from combined data. By establishing a common methodology, factors that might influence the differences in results from previous studies can more easily be explored. Administrative support was provided to ensure that the highest quality data were used in the analysis. It is anticipated that the PAPA results will contribute to the international scientific discussion of how to conduct and interpret time-series studies of air pollution and will stimulate the development of high-quality routine systems for recording daily deaths and hospital admissions for time-series analysis. METHODS: Mortality data were retrieved from routine databases with underlying causes of death coded using the World Health Organization (WHO) International Classification of Diseases, 9th revision or 10th revision (ICD-9, ICD-10). Air quality measurements included nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with aerodynamic diameter < or = 10 microm (PM10), and ozone (O3) and were obtained from several fixed-site air monitoring stations that were located throughout the metropolitan areas of the four cities and that met the standards of procedures for quality assurance and quality control carried out by local government units in each city. Using the Common Protocol, an optimized core model was established for each city to assess the effects of each of the four air pollutants on daily mortality using generalized linear modeling with adjustments for time trend, seasonality, and other time-varying covariates by means of a natural-spline smoothing function. The models were adjusted to suit local situations by correcting for influenza activity, autocorrelation, and special weather conditions. Researchers in Hong Kong, for example, used influenza activity based on frequency of respiratory mortality; researchers in Hong Kong and Shanghai used autoregressive terms for daily outcomes at lag days; and researchers in Wuhan used additional smoothing for periods with extreme weather conditions. RESULTS AND DISCUSSION: For mortality due to all natural (nonaccidental) causes at all ages, the effects of air pollutants per 10-microg/m3 increase in concentration was found to be higher in Bangkok than in the three Chinese cities, with the exception of the effect of NO2 in Wuhan. The magnitude of the effects for cardiovascular and respiratory mortality were generally higher than for all natural mortality at all ages. In addition, the effects associated with PM10 and O3 in all natural, cardiovascular; and respiratory mortality were found to be higher in Bangkok than in the three Chinese cities. The explanation for these three findings might be related to consistently higher daily mean temperatures in Bangkok, variations in average time spent outdoors by the susceptible populations, and the fact that less air conditioning is available and used in Bangkok than in the other cities. However, when pollutant concentrations were incorporated into the excess risk estimates through the use of interquartile range (IQR), the excess risk was more comparable across the four cities. We found that the increases in effects among older age groups were greater in Bangkok than in the other three cities. After excluding data on extremely high concentrations of PM10 in Bangkok, the effect estimate associated with PM10 concentrations decreased in Bangkok (suggesting a convex relationship between risk and PM10, where risk levels off at high concentrations) instead of increasing, as it did in the other cities. This leveling off of effect estimates at high concentrations might be related to differences in vulnerability and exposure of the population to air pollution as well as to the sources of the air pollutant. IMPLICATIONS OF THE STUDY: The PAPA project is the first coordinated Asian multicity air pollution study ever published; this signifies the beginning of an era of cooperation and collaboration in Asia, with the development of a common protocol for coordination, data management, and analysis. The results of the study demonstrated that air pollution in Asia is a significant public health burden, especially given the high concentrations of pollutants and high-density populations in major cities. When compared with the effect estimates reported in the research literature of North America and Western Europe, the study's effect estimates for PM10 were generally similar and the effect estimates for gaseous pollutants were relatively higher. In Bangkok, however, a tropical city where total exposures to outdoor pollution might be higher than in most other cities, the observed effects were greater than those reported in the previous (i.e., Western) studies. In general, the results suggested that, even though social and environmental conditions across Asia might vary, it is still generally appropriate to apply to Asia the effect estimates for other health outcomes from previous studies in the West. The results also strongly support the adoption of the global air quality guidelines recently announced by WHO.

Risk factors affecting visual-motor coordination deficit among children residing near a petrochemical industrial estate.

Thailand has been changed to rapid urbanization and industrialization since 1980s. During 1992 through 1996, the number of industrial factories in Rayong province increased very sharply. The major types of industries are petrol-chemical and plastic production. However, after the petrochemical industry boomed, the higher demand led to an industrial area expansion. The establishment of factories in this area leads to serious environmental and health impacts. The study aims to investigate the factors that affect visual-motor coordination deficit among children, 6-13 years of age, residing near the Petrochemical Industrial Estate, Map Ta Phut, Rayong province. A population-based cross-sectional study was employed for collecting data on neurobehavioral effects using the Digit Symbol Test. The study found one-third of 2,956 children presented with visual-motor coordination deficits. Three factors were identified that caused children to have a higher risk of visual-motor coordination deficits: gender (adjusted OR 1.934), monthly parental income (range of adjusted OR 1.977 - 2.612), and household environmental tobacco smoke (adjusted OR 1.284), while age (adjusted OR 0.874) and living period (adjusted OR 0.954) in study areas were reversed effects on visual-motor coordination deficit among children. The finding indicated that children with visual-motor coordination deficit were affected by gender, monthly parental income, age of children, length of living period, and household environmental tobacco smoke.

Air pollution and respiratory symptoms: results from three panel studies in Bangkok, Thailand.

Several studies in North American cities have reported associations between air pollution and respiratory symptoms. Replicating these studies in cities with very different population and weather characteristics is a useful way of addressing uncertainties and strengthening inferences of causality. To this end we examined the responses of three different panels to particulate matter (PM) air pollution in Bangkok, Thailand, a tropical city characterized by a very warm and humid climate. Panels of schoolchildren, nurses, and adults were asked to report daily upper and lower respiratory symptoms for 3 months. Concentrations of daily PM(10) (PM with a mass median aerodynamic diameter less than 10 microm) and PM(2.5) (airborne particles with aerodynamic diameters less than 2.5 microm) were collected at two sites. Generally, associations were found between these pollution metrics and the daily occurrence of both upper and lower respiratory symptoms in each of the panels. For example, an interquartile increase of 45 microg/m(3) in PM(10) was associated with about a 50% increase in lower respiratory symptoms in the panel of highly exposed adults, about 30% in the children, and about 15% in the nurses. These estimates were not appreciably altered by changes in the specification of weather variables, stratification by temperature, or inclusion of individual characteristics in the models; however, time trends in the data cause some uncertainty about the magnitude of the effect of PM on respiratory symptoms. These pollutants were also associated with the first day of a symptom episode in both adult panels but not in children. The estimated odds ratios are generally consistent with and slightly higher than the findings of previous studies conducted in the United States.

Indoor/outdoor PM10 and PM2.5 in Bangkok, Thailand.

Twenty-four-hour averaged PM10 and PM2.5 concentrations were obtained by using 4-liter-per-minute-pumps and impactors in microenvironments of a busy shopping district and a university hospital campus. In both areas, most people live directly adjacent to their worksites--minimizing the need to measure commuting exposure as part of total daily exposure. Co-located samplers were set in indoor microenvironments, the near-ambient zone of the households, and at nearby streetside central ambient monitoring stations. Smoking and use of other indoor PM sources were recorded daily via questionnaires. Consistent with previous studies, smoking and the use of charcoal stoves increased indoor particulate matter levels. The sampled air-conditioned hospital area had substantially lower particle concentrations than outdoors. A simple total exposure model was used to estimate the human exposure. The averaged ratios of co-located PM2.5/PM10 concentrations in various microenvironments are reported for each location. A single daily indoor average PM10 concentration for all households measured in a given sampling day is calculated for correlation analysis. Results showed that day-to-day fluctuations of these calculated indoor PM10 levels correlated well with near-ambient data and moderately well with ambient data collected at the nearby central monitoring site. This implies that ambient monitors are able to capture the daily variations of indoor PM levels or even personal exposure and may help explain the robust association of ambient PM levels and health effects found in many epidemiological studies. Absolute PM exposures, however, were substantially underestimated by ambient monitors in the shopping district, probably because of strong local sources.

The impact of particulate matter on daily mortality in Bangkok, Thailand.

Several studies conducted in U.S. cities report an association between acute exposures to particulate matter (PM), usually measured as PM10, and mortality. Evidence of high concentrations of PM10 in Eastern Europe and in large metropolitan areas outside of the United States, such as Mexico City and Bangkok, underscores the need to determine whether these same associations occur outside of the United States. In addition, conducting studies of mortality and air pollution in regions that have distinctly different seasonal patterns than those of the United States provides an effective opportunity to assess the potentially confounding aspects of seasonality. Over the last few years, daily measures of ambient PM10 have been collected in Bangkok, a tropical city of over 6 million people. In this metropolitan area, PM10 consists largely of fine particles generated from diesel- and gasoline-powered automobiles, and from two-stroke motorcycle engines. Our analysis involved the examination of the relationship between PM10 and daily mortality for 1992 through 1995. In addition to counts of daily natural mortality (total mortality net of accidents, homicides, and suicides), the data were compiled to assess both cardiovascular and respiratory mortality, and natural mortality by age group. A multivariate Poisson regression model was used to explain daily mortality while controlling for several covariates including temperature, humidity, day of the week, season, and time. The analysis indicated a statistically significant association between PM10 and all of the alternative measures of mortality. The results suggest a 10-microgram/m3 change in daily PM10 is associated with a 1-2% increase in natural mortality, a 1-2% increase in cardiovascular mortality, and a 3-6% increase in respiratory mortality. These relative risks are generally consistent with or greater than those reported in most studies undertaken in the United States.