[Time-series analysis on the relationship between ambient PM2.5 and daily outpatient visits due to allergic conjunctivitis among children in Shenzhen].

Objective: To explore the short-term effects of ambient PM _2.5 on the outpatient visits of allergic conjunctivitis among children in Shenzhen. Methods: It was a ecological study. Data on daily visits including date of visit, sex and age from children with allergic conjunctivitis were collected from Shenzhen Eye Hospital and Shenzhen Children's Hospital in 2018. Related data on air pollution (PM _2.5 , PM ₁₀ , SO ₂ , NO ₂ , CO and O ₃ ) and meteorology (atmospheric pressure, temperature and relative humidity) were also collected. Pearson correlation analysis was used for normal distribution data and Spearman rank correlation analysis was used for non-normal distribution data. Generalized additive model was used to estimate the impact of PM _2.5 pollution on allergic conjunctivitis outpatients and the lagging effects. Results: In 2018, there were 16 133 allergic conjunctivitis outpatients in the two hospitals. The maximum age was 18 years and the minimum age was 2 months. Males accounted for 49.3%. The daily average concentration of PM _2.5 was 22 (15, 31) μg/m ³ . Changes of the concentration of PM _2.5 had a positive correlation with the amount of allergic conjunctivitis visits, and the Spearman correlation coefficient was 0.150 ( P =0.004). The single pollutant model showed that the strongest effect appeared at 3 days ( RR =1.111， 95% CI :1.071-1.152). A 10 μg/m ³ increase of PM _2.5 would result in an excessive number of allergic conjunctivitis outpatients as much as 11.112% (95% CI ：7.011%-15.212%). In the multiple air pollutants models, after the introduction of NO ₂ , O ₃ and CO, the concentration of PM _2.5 showed an enhanced effect on the number of hospital visits due to allergic conjunctivitis on the same day, and the difference was statistically significant ( P <0.05). Conclusion: Changes of the concentration of PM _{2.5 h} ad a positive correlation with daily outpatient visits of allergic conjunctivitis among children in Shenzhen. (Chin J Ophthalmol, 2020, 56: 608-614) .