Objective To assess the association between the concentration of the air pollutant PM2.5 and daily outpatient visits for respiratory disease. Methods All records of daily outpatient visits to three hospitals in Shenzhen from January 1 to December 31, 2013 were collected. Daily air pollution monitoring and meteorology data from the same period were also collected in Shenzhen. The data were analyzed using a semiparametric generalized additive model with Poisson distribution of time series analysis controlling for long-term and seasonal trends, flu, DOW, public holidays, and meteorological factors. The excess risk (ER) of respiratory disease and its 95%CI value were calculated, along with the incremental increase of 10 μg/m3 in PM2.5 concentration. Results Number of outpatient visits for respiratory diseases totaled 1 428 672 (daily range:1 790-5 228). The annual average PM2.5 concentration was 40.2μg/m3 (daily range:7.2-137.1μg/m3). The lag1 factor had the most significant impact on the lag effect. We estimated that a 10 μg/m3 increase in day-before PM2.5 concentration was associated with a 1.809% (95% CI:1.709%-1.909%) ER of visits for respiratory disease. After controlling for other pollutants (NO2, CO, and O3), the effect remained stable. When NO2, CO, and O3 were introduced separately, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of daily outpatient visits for respiratory disease was 1.814% (95% CI:1.706%-1.923%), 2.780% (95% CI: 2.668%-2.892%), and 1.513% (95% CI: 1.403%-1.624%), respectively. With simultaneous control of NO2 and O3, NO2 and CO, and CO and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 1.369% (95% CI: 1.242%-1.497%), 2.709% (95% CI: 2.590%- 2.828% ), and 2.577% (95% CI: 2.452%- 2.702% ), respectively. With simultaneous control of NO2, CO, and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 2.370% (95% CI: 2.231%-2.509%). Conclusions PM2.5 can increase the risk of outpatient visits for respiratory disease in Shenzhen.

Objective To assess the association between the concentration of the air pollutant PM2.5 and daily outpatient visits for respiratory disease. Methods All records of daily outpatient visits to three hospitals in Shenzhen from January 1 to December 31, 2013 were collected. Daily air pollution monitoring and meteorology data from the same period were also collected in Shenzhen. The data were analyzed using a semiparametric generalized additive model with Poisson distribution of time series analysis controlling for long-term and seasonal trends, flu, DOW, public holidays, and meteorological factors. The excess risk (ER) of respiratory disease and its 95%CI value were calculated, along with the incremental increase of 10 μg/m3 in PM2.5 concentration. Results Number of outpatient visits for respiratory diseases totaled 1 428 672 (daily range:1 790-5 228). The annual average PM2.5 concentration was 40.2μg/m3 (daily range:7.2-137.1μg/m3). The lag1 factor had the most significant impact on the lag effect. We estimated that a 10 μg/m3 increase in day-before PM2.5 concentration was associated with a 1.809% (95% CI:1.709%-1.909%) ER of visits for respiratory disease. After controlling for other pollutants (NO2, CO, and O3), the effect remained stable. When NO2, CO, and O3 were introduced separately, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of daily outpatient visits for respiratory disease was 1.814% (95% CI:1.706%-1.923%), 2.780% (95% CI: 2.668%-2.892%), and 1.513% (95% CI: 1.403%-1.624%), respectively. With simultaneous control of NO2 and O3, NO2 and CO, and CO and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 1.369% (95% CI: 1.242%-1.497%), 2.709% (95% CI: 2.590%- 2.828% ), and 2.577% (95% CI: 2.452%- 2.702% ), respectively. With simultaneous control of NO2, CO, and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 2.370% (95% CI: 2.231%-2.509%). Conclusions PM2.5 can increase the risk of outpatient visits for respiratory disease in Shenzhen.