Long-term changes in air pollution and health implications in four Chinese cities

Abstract

The rapid increase in energy consumption resulting from rapid economic growth in the past decade or so has produced high stress on China's urban air quality. A variety of approaches (e.g., the nationwide Blue Sky Program) directly or indirectly related to energy infrastructural and technology interventions have, consequently, been implemented to improve urban air quality. It is important to assess the effectiveness of these approaches in improving air quality and ultimately public health. In this paper, we use the data, collected as part of an epidemiological study of air pollution health effects, to examine long-term changes in air pollution levels and in respiratory morbidity prevalence in the four Chinese cities of Chongqing, Guangzhou, Lanzhou, and Wuhan. Over four urban and four suburban districts of the four cities, outdoor concentrations of total suspended particles (TSP) were reduced by 58 μg/m 3 or 16.5 % from the 1993-1994 level to the 1999-2000 level, those of sulfur dioxide (SO 2 ) were reduced by 42 μg/m 3 or 39 % from the 1993-1994 level to the 2002-2003 level, those of PM 10 were reduced by 32 μg/m 3 or 21 % from the 1995-1996 level to the 2002-2003 level, and those of oxides of nitrogen (NO x ) were reduced by 14 μg/m 3 or 17 % from the 1993-1994 level to the 1998-1999 level. These pollutant concentration changes were “translated” into morbidity prevalence changes, using the concentration-response relationships observed across the eight districts in the epidemiological study. Our estimates indicate that the overall reductions in TSP and PM 10 concentrations led to ~30 % and ~50 % reductions in school children's prevalence rates of persistent phlegm and bronchitis, respectively, and a ~30 % reduction infemale adults' prevalence rates of wheeze and persistent phlegm. In male adults, the TSP reduction generated the largest morbidity prevalence reductions, up to 50 % for bronchitis, among all the pollutants. The SO 2 reduction was only found to bring in prevalence reductions in adults for a few morbidity outcomes. When interpreting these results, however, an important caveat needs to be added, which is that our estimates of current prevalence rates used the average values of all confounding factors at the 1993-1996 levels. Changes in many of these confounding factors have expectedly occurred in the four cities, which may moderate or magnify health effects associated with changes in air pollution.