Modifying Factors for Air Pollution- Related Deaths in Shanghai, China

Abstract:

Various factors may modify the health effect of outdoor air pollution. Prior findings about modifiers are inconsistent, and most of these studies were conducted in developed countries. We conducted a time-series analysis to examine the modifying effect of season, gender, age and education on the association between outdoor air pollutants (PM10, SO2, NO2 and O3) and daily mortality in Shanghai, China, using four years of daily data (2001-2004). Natural spline model was used to analyze the data. We examined effects of air pollution for the warm season (from April to September) and cool season (from October to March) separately. For total mortality, we examined the association stratified by gender and age. Stratified analysis by educational attainment was conducted for total, cardiovascular and respiratory mortality. It was found that outdoor air pollution was associated with mortality from all causes and from cardiorespiratory diseases in Shanghai. An increase of 10µg/m3 of 2-day average concentrations of PM10, SO2, NO2 and O3 corresponds to 0.25% (95%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%) increase of all-cause mortality. The effects of air pollutants were more evident in the cool season than in the warm season. 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). Our results suggest that season, gender, 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.