the association between shortterm exposure to fine particulate matter and outpatient visit in beijing, china

Background: we tried to investigate the effect of pm2.5 on daily counts of outpatient visits in the guang’anmen hospital to determine if short-term pm2.5 exposure with extremely high concentration affects cardiopulmonary func-tion of beijing residents. methods: outpatient visits and pm2.5 data from 01/11/2011 to 03/31/2013 were extracted from the guang’anmen hospital and the american embassy in beijing, respectively. followed by using a semi-parametric generalized additive model (gam) with time dependent covariates, we analyzed the association between pm2.5 concentrations and daily count of outpatient visits on day 0, 1, 2, 3, 4 and 5 of pm2.5 exposure. results: overall, 284354 subjects were collected. there were significant associations of short-term pm2.5 exposures with outpatient visits for cardiopulmonary diseases (p<0.05). specifically, a 10 μg/m³ increase in pm2.5 was positively associated with a 0.74% of increase in angina visit on the first day and 0.50% increased visit on the second day (p<0.05). with an increase in pm2.5, the cough and respiratory visits significantly decreased by 0.17% and 0.30% on the first day, respectively (p<0.05). however, there were significant positive associations of pm2.5 with increased cough and respiratory visits (increased by 0.17% and 0.10%, respectively) on the fifth day (p<0.05). conclusion: our association studies showed an instant effect of pm2.5 level on cardiovascular outpatient visit in the guang’anmen hospital in beijing while a lag effect on respiratory outpatient visits.