[PM _2.5 and Emergency Calls for Health with Respiratory Diseases in Chengdu in 2017]

To determine the association between daily particulate matter 2.5 (PM _2.5) mass and emergency calls for help with respiratory diseases.

Semi-parametric generalized additive model was established to determine the association between daily PM _2.5 and emergency calls for help with respiratory diseases in 2017 in Chengdu, after adjustments for time trend and variations in the days of the week and weather conditions.

In 2017, a total of 9 309 emergency calls for help with respiratory diseases were recorded in Chengdu: on average 26 calls a day. Over the year, Chengdu reported a mean PM _2.5 mass concentration of 53.6 μg/m ³, an average temperature of 16.6 ℃, and an average relative humidity of 81.2%. The single pollutant model with lag time effect showed that a 10 μg/m ³ increase in PM _2.5 was associated with an increase of 1.26% (95% confidence interval ( CI) 0.56%-1.97%) emergency calls for help with respiratory diseases. The exposure-response was almost in a direct line. The dual pollutant model found that O ₃ 8-hour sliding average (O _{3-8 h}) enhanced the effect of PM _2.5 on emergency calls for help with respiratory diseases.

Outdoor PM _2.5 is a significant predictor of emergency calls for help with respiratory diseases in Chengdu.