| Air pollution episodes have taken place in the1940-60s, which has shocked the world. These events have caused great harm to human health and ecological environment, and raised the widespread concern of the acadamic and the public. With the extensive research, researchers found the adverse health effects of air pollutant concentrations even at below-guideline levels. According to the estimates of the world health organization, the number of population deaths exceeded2.7million in2003.Although China has worked hard at controlling air pollution in past ten years and air quality has been improved in many cities, China is still facing the worst air pollution problem and health impacts and economic loss due to air pollution. According to the statistics of the world bank (2007), national health cost was up to157-520billion Chinese yuan associated with air pollution in cities, accounting for1.2-3.3%of the gross domestic product (GDP). At present, coal has been and is still the main source of energy in China, constituting about75%of all energy sources. Consequently, air pollution mainly consists of coal smoke, with sulfur dioxide (SO2) and suspended particulater matter (PM) as the principal air pollutants. With the increase in urbanization, industrialization, and number of motor vehicles, air pollution in large cities of China has gradually changed from the conventional coal combution type to the mixed coal combustion/motor vehicle emission type.In recent years, numerous epidemiological studies have reported the associations between different air pollutants and the incidence of various health endpoints, including increases in daily mortality. Among the various air pollutants, atmospheric particulate matter (PM) has shown the strongest evidence for adverse health effects. In the1990s, epidemiological studies have been conducted in large cities of China. because of the lack of data and techniques, the exposure-response function in America and Europe was often adopted as health effects of air pollution in China. However, compared with the developed countries such as Western Europe and America, China has significant difference in levels of air pollution concentration, characteristics of air pollutant components, social demographic characteristics of local population such as age and sex distribution, education levels and so on. So pollution exposure-response relationships from developed countries could not applied to Chinese regions. We should take account of local conditions, and provide more accurate evidence to the policymakers of air quality and health index.Tianjin city was chosen as the study area because of its serious air pollution. Both the change characteristics of air pollution in recent years and the concentration of particulate matter with different sizes one year were analyzed. Furthermore, the relationship between air pollution and daily non-accidental mortality and cause-specific mortality including cardiovascular, cerebrovascular, respiratory diseases were studied using generalized additive model (GAM) and stratified by sex, age, educational levels and seasonality. Thirdly, the associations between dfferent size fractions of particulate air pollutants and total and cause-specific mortalities were also investigated and analyzed. Some meaning results were obtained.1. The principal air pollutants SO2, NO2and PM10in Tianjin City have been decreasing gradually in recent years. PM10concentrations changed greatly in the different months, while NO2and SO? had relative small variation with the U curves. In that, SO2and NO2concentration were high in the first and by the end of the year and were low in the rest of the year. Different size fractions of particles during the sampling time had similar change trends. In addition, varied trends of fine particualte matter PM2.5and PM1.0were basically identical.2. PM10has been statistically and significantly associated with total non-accidental deaths, respiratory diseases, heart diseases and stroke deaths including ischemic heart disease and ischemic stroke deaths. After adjusting for SO2and NO?, the health effect of PM10was roughly stable except for ischemic heart disease and ischemic stroke. SO2and NO2have been significantly positive associated with total and cause-specific mortalities. However, the mortality effects of SO2and NO2were not statistically significant after the adjustment of other pollutants, respectively.3. In stratified analysis by sex, age, and educational levels, men were more vulnerable to the effects of air pollution than women. The elderly were more sensitive to the effects of air pollution than the younger.Compared with population groups with high education degrees, population groups with the low education level were more vulnerable to the adverse effects of atmospheric pollution. Furtermore, In seasonal hierarchical analysis, residents in the warm seasons were more strongly affected by air pollution than those in the cold seasons.4. In a single pollutant model, different size fractions of particles (including PM10, PM2.5PMi, PM10-2.5, and PM2.5.1) had acute effects on total non-accidental mortality, other mortality of heart diseases, stroke respiratory diseases. Besides, PM1.0had the most significant positive association with cause-specific mortality. In two and multi pollutant models, the relation between PMi and total mortality or other disease mortality was stable after the adjustment for other different particles.5. In a single pollutant model, PM1-2.5and PM2.5-10only had associations with increased total non-accidental deaths. However, in multi-pollutant models the mortality effects of PM1-2.5and PM2.5-10had not statistically significant level after adjusting for other particles or gaseous pollutants.6. The models mostly showed the non-linear and linear relationships for the relative risks of death for all causes (total deaths) and for specific causes in relation to different air pollutants (SO2, NO2and PMjo) and size fractions of particulate matter (PM1, PM10-2.5. and PM1-2.5). Whether in the non-linear or linear relationships, there were no threshold levels. |
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