Short-term effects of air pollutants on daily outpatient visits for hair loss: a multi-city time-series study in southwest China

Background: Few epidemiologic studies have evaluated the association between air pollution and hair loss. The aim of this study was to investigate the association between PM _2.5 , PM ₁₀ , SO ₂ and NO ₂ and the number of daily outpatient visits for hair loss outpatient visits in Sichuan Province, China. Methods: This study collected records of 95,535 hair loss outpatient visits from medical institutions in 21 cities in Sichuan Province, China, from 2017-2019, as well as meteorological data and air pollutant data from environmental monitoring stations in Sichuan Province for the same period. A generalized additive model (GAM) was used to analyze the association and lagged effects of air pollutants with the number of hair loss outpatient visits after controlling for long-term trends, public holidays, weekdays, and meteorological factors. Results: The adverse effect of PM _2.5 , PM ₁₀ and NO ₂ on the number of hair loss outpatient visits was maximized at lag 07, with RR values of 1.017 (95% CI:1.009-1.025), 1.012 (95% CI:1.006-1.018), and 1.054 (95% CI:1.029-1.079), respectively. No significant effect of SO ₂ on the number of hair loss outpatient visits was observed. In the stratified analysis, we found that PM _2.5 and PM ₁₀ had a more significant effect on the male population (p<0.05). PM _2.5 and PM ₁₀ had a more significant impact on the 19-59 year old population compared to other age groups (p<0.05). PM _2.5 and PM ₁₀ had a greater impact on the number of hair loss outpatient visits in the cool season than in the warm season (p<0.05). Conclusion: Our study suggests that short-term exposure to PM _2.5 , PM ₁₀ and NO ₂ leads to an increase in hair loss outpatient visits, and that the government should take action to mitigate air pollution and increase protection for sensitive populations during the cold season.