Association between air pollution and upper respiratory tract infection in hospital outpatients aged 0-14 years in Hefei, China: a time series study.

OBJECTIVE: To investigate the association between air pollution and upper respiratory tract infection (URTI) in children aged 0-14 years in Hefei, China in 2014-2015.

STUDY DESIGN: An ecological method (i.e. generalised additive model [GAM]) was used to explore the effects of air pollutants on paediatric hospital outpatients with URTI.

METHODS: GAM was used to evaluate the lag effects (including lag0 to lag6, lag01 and lag06) between daily changes in particulate matter (PM10 ), fine particulate matter (PM2.5 ), sulphur dioxide (SO2 ), nitrogen dioxide (NO2 ), ozone (O3 ) and carbon monoxide (CO) and the number of hospital outpatients with URTI in 2014-2015, after controlling for the confounding effects of long-term trends, seasonality, day of the week, public holidays and meteorological factors.

RESULTS: PM10 , PM2.5 , SO2 , NO2 and CO in the single-pollutant models had significant positive effects on the number of paediatric hospital outpatients with URTI. It was found that per 10 μg/m3 increasing in concentrations of PM10 at lag3, PM2.5 , SO2 , NO2 and CO at lag06 were associated with an increase of Excess risk (ER) with 0.15% (95% CI: 0.07%∼0.23%), 0.38% (95% CI: 0.17%∼0.60%), 2.92% (95% CI: 1.88%∼3.97%), 4.47% (95% CI: 3.69%∼5.25%) and 0.05% (95% CI: 0.02%∼0.08%), respectively. Only NO2 remained significantly positively associated with the number of hospital outpatients with URTI in the full-pollutant models, and ERs were 4.72% (95% CI = 3.76%-5.69%) and 4.70% (95% CI = 3.76%-5.65%) per 10 μg/m3 increase in NO2 in Model 1 (including PM10, SO2 , NO2 , O3 and CO) and Model 2 (including PM2.5 , SO2 , NO2 , O3 and CO), respectively.

CONCLUSION: This study showed that short-term exposure to air pollution was associated with increased risk of URTI among paediatric hospital outpatients aged 0-14 years in Hefei. NO2 was the major air pollutant affecting the daily number of paediatric hospital outpatients with URTI.