Short-term association between sulfur dioxide and daily mortality: The Public Health and Air Pollution in Asia (PAPA) study

Abstract

Sulfur dioxide (SO2) has been associated with increased mortality and morbidity, but few studies were conducted in Asian countries. Previous studies suggest that SO2 may have adverse health effects independent of other pollutants. In the Public Health and Air Pollution in Asia (PAPA) project, the short-term associations between ambient sulfur dioxide (SO2) and daily mortality were examined in Bangkok, Thailand, and three Chinese cities: Hong Kong, Shanghai, and Wuhan. Poisson regression models incorporating natural spline smoothing functions were used to adjust for seasonality and other time-varying covariates. Effect estimates were obtained for each city and then for the cities combined. The impact of alternative model specifications, such as lag structure of pollutants and degree of freedom (df) for time trend, on the estimated effects of SO2 were also examined. In both individual-city and combined analysis, significant effects of SO2 on total non-accidental and cardiopulmonary mortality were observed. An increase of 10 μg/m3 of 2-day moving average concentrations of SO2 corresponded to 1.00% [95% confidence interval (CI), 0.75-1.24], 1.09% (95% CI, 0.71-1.47), and 1.47% (95% CI, 0.85-2.08) increase of total, cardiovascular and respiratory mortality, respectively, in the combined analysis. Sensitivity analyses suggested that these findings were generally insensitive to alternative model specifications. After adjustment for PM10 or O3, the effect of SO2 remained significant in three Chinese cities. However, adjustment for NO2 diminished the associations and rendered them statistically insignificant in all four cities. In conclusion, ambient SO2 concentration was associated with daily mortality in these four Asian cities. These associations may be attributable to SO2 serving as a surrogate of other substances. Our findings suggest that the role of outdoor exposure to SO2 should be investigated further in this region.

Air Pollution and Health Studies in China—Policy Implications

“…28 In addition, an intervention study in Hong Kong cutting down sulfur concentration in fuels has demonstrated direct health benefits after significant decrease in ambient SO 2 levels. 29 On the other hand, due to rapid increase in the number of motor vehicles, the MOEP is considering to add "total emission of NO 2 " as another index of air pollution control.…”

Hospital out-and-in-patients as Functions of Trace Gaseous Species and Other Meteorological Parameters in Chiang-Mai, Thailand

“…Several empirical studies highlight the association of nitrogen dioxide (NO 2 ), ozone (O 3 ), sulfur dioxide (SO 2 ) and carbon monoxide (CO) with adverse short-term effects, including increases in daily mortality, particularly cardiorespiratory mortality, and morbidity (Kan et al, 2010;Sousa et al, 2012;Zhang et al, 2013). NO 2 and O 3 have been observed to influence principally respiratory outcomes, while CO predominantly affects the cardiac system (Katsouyanni et al, 2011).…”

Spatiotemporal characteristics and health effects of air pollutants in Shenzhen

“…The longterm effect of exposure to low-concentration SO 2 is similar to the short-term effect of exposure to high-concentration SO 2 in many industrial settings and chemical industries. Numerous epidemiological studies have suggested that SO 2 exposure is associated with health risk and mortality caused by respiratory tract diseases, lung cancer, and cardiovascular diseases (Meltzer et al, 2009;Kan et al, 2010;Meng et al, 2013;Guarnieri and Balmes, 2014). The greatest RRs in mortality number with a 10 mg/m 3 increase of SO 2 were CO is a colorless, tasteless, odorless, and nonirritating gas that is a product of incomplete combustion of carbon-containing fuels (Nathan, 2007;Chen et al, 2011).…”

“…Annual NO 2 concentration was higher in western Shenzhen, which can be related to greater traffic or indoor combustion emissions there. SO 2 is a traditional pollutant of industrial origin related to combustion of coal and other fossil fuels (Kan et al, 2010). SO 2 had greater concentrations in eastern Shenzhen, and the lowest CO concentrations were in the Luohu District.…”