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BACKGROUND: Various factors can modify the health effects of outdoor air pollution. Prior findings about modifiers are inconsistent, and most of these studies were conducted in developed countries. OBJECTIVES: We conducted a time-series analysis to examine the modifying effect of season, sex, age, and education on the association between outdoor air pollutants [particulate matter < 10 µm in aerodynamic diameter (PM10), sulfur dioxide, nitrogen dioxide, and ozone] and daily mortality in Shanghai, China, using 4 years of daily data (2001--2004). METHODS: Using a natural spline model to analyze the data, we examined effects of air pollution for the warm season (April--September) and cool season (October--March) separately. For total mortality, we examined the association stratified by sex and age. Stratified analysis by educational attainment was conducted for total, cardiovascular, and respiratory mortality. RESULTS: Outdoor air pollution was associated with mortality from all causes and from cardio-respiratory diseases in Shanghai. An increase of 10 µg/m3 in a 2-day average concentration of PM10, SO2, NO2, and O3 corresponds to increases in all-cause mortality of 0.25% [95% confidence interval (CI), 0.14--0.37), 0.95% (95% CI, 0.62--1.28), 0.97% (95% CI, 0.66--1.27), and 0.31% (95% CI, 0.04--0.58), respectively. The effects of air pollutants were more evident in the cool season than in the warm season, and females and the elderly were more vulnerable to outdoor air pollution. Effects of air pollution were generally greater in residents with low educational attainment (illiterate or primary school) compared with those with high educational attainment (middle school or above). CONCLUSIONS: Season, sex, age, and education may modify the health effects of outdoor air pollution in Shanghai. These findings provide new information about the effects of modifiers on the relationship between daily mortality and air pollution in developing countries and may have implications for local environmental and social policies. INSET: 4. [ABSTRACT FROM AUTHOR]

BACKGROUND: Controversy remains regarding the relationship between ambient ozone and mortality worldwide. In mainland China, the largest developing country, there has been no prior study investigating the acute effect of O3 on death risk. Given the changes in types of air pollution from conventional coal combustion to the mixed coal combustion/motor vehicle emissions in China's large cities, it is worthwhile to investigate the acute effect of O3 on mortality outcomes in the country. OBJECTIVES: We conducted a time-series study to investigate the relation between O3 and daily mortality in Shanghai using 4 years of daily data (2001–2004). METHODS: We used the generalized additive model with penalized splines to analyze mortality, O3 pollution, and covariate data in warm and cold seasons. We considered daily counts of all-cause mortality and several cause-specific subcategories (respiratory and cardiovascular). We also examined these associations among several subpopulations based on age and sex. RESULTS: O3 was significantly associated with total and cardiovascular mortality in the cold season but not in the warm season. In the whole-year analysis, an increase of 10 μg/m² of 2-day average (lag01) O3 corresponds to 0.45% [95% confidence interval (CI), 0.16–0.73%], 0.53% (95% CI, 0.10–0.96%), and 0.35% (95% CI, -0.40 to 1.09%) increase of total nonaccidental, cardiovascular, and respiratory mortality, respectively. In the cold season, the estimates increased to 1.38% (95% CI, 0.68–2.07%), 1.53% (95% CI, 0.54–2.52%), and 0.95% (95% CI, -0.71 to 2.60%), respectively. In the warm season, we did not observe significant associations for both total and cause-specific mortality. The results were generally insensitive to model specifications such as lag structure of O3 concentrations and degree of freedom for time trend. Multipollutant models indicate that the effect of O3 was not confounded by particulate matter ≤ 10 μm in diameter (PM10) or by sulfur dioxide; however, after adding nitrogen dioxide into the model, the association of O3 with total and cardiovascular mortality became statistically insignificant. CONCLUSIONS: O3 pollution has stronger health effects in the cold than in the warm season in Shanghai. Our analyses also strengthen the rationale for further limiting levels of O3 pollution in outdoor air in the city. [ABSTRACT FROM AUTHOR]