Short-term ambient air pollution exposure and adult primary insomnia outpatient visits in Chongqing, China: A time-series analysis

Growing evidence suggest that air pollutants can be associated with sleep disorders. However, no study has explored the association of short-term air pollution exposure with primary insomnia, a specific type of sleep disorders. To evaluate the correlation of short-term air pollution exposure with adult primary insomnia outpatient visits in Chongqing, China, we collected data of adult primary insomnia outpatient visits and air pollutants' concentrations between 2013 and 2019 and the associations were estimated with single-day lags as well as moving average lags using a generalized additive model. Totally, 23,919 outpatient visits for adult primary insomnia were identified. The daily data of adult insomnia outpatient visits, air pollutants (NO2, CO, SO2, O3, PM10 and PM2.5) and meteorological conditions (daily mean temperature and relative humidity) were gathered. Short-term exposure to multiple air pollutants, especially NO2 and SO2, was associated with adult primary insomnia visits. A 10 μg/m3 increase in NO2 and SO2 at lag 05 corresponded to increased primary insomnia outpatient visits 3.87% (95% CI: 1.50%-6.24%) and 7.22% (95% CI: 2.10%-12.35%), respectively. Moreover, stronger links were presented in females and cool seasons for NO2 while in the elderly for SO2. Collectively, this time-series study suggested that short-term exposure to air pollutants, especially to NO2 and SO2, was associated with higher risk of adult primary insomnia outpatient visits, and such association could to be sex-, age-, and season-modified.