Changes in ambient temperature increase hospital outpatient visits for allergic rhinitis in Xinxiang, China.

Background: The effect of ambient temperature on allergic rhinitis (AR) remains unclear. Accordingly, this study aimed to explore the relationship between ambient temperature and the risk of AR outpatients in Xinxiang, China.

Method: Daily data of outpatients for AR, meteorological conditions, and ambient air pollution in Xinxiang, China were collected from 2015 to 2018. The lag-exposure-response relationship between daily mean temperature and the number of hospital outpatient visits for AR was analyzed by distributed lag non-linear model (DLNM). Humidity, long-time trends, day of the week, public holidays, and air pollutants including sulfur dioxide (SO), and nitrogen dioxide (NO) were controlled as covariates simultaneously.

Results: A total of 14,965 AR outpatient records were collected. The relationship between ambient temperature and AR outpatients was generally M-shaped. There was a higher risk of AR outpatient when the temperature was 1.6-9.3 °C, at a lag of 0-7 days. Additionally, the positive association became significant when the temperature rose to 23.5-28.5 °C, at lag 0-3 days. The effects were strongest at the 25th (7 °C) percentile, at lag of 0-7 days (RR: 1.32, 95% confidence intervals (CI): 1.05-1.67), and at the 75th (25 °C) percentile at a lag of 0-3 days (RR: 1.15, 95% CI: 1.02-1.29), respectively. Furthermore, men were more sensitive to temperature changes than women, and the younger groups appeared to be more influenced.

Conclusions: Both mild cold and mild hot temperatures may significantly increase the risk of AR outpatients in Xinxiang, China. These findings could have important public health implications for the occurrence and prevention of AR.