Associations between atmospheric particulate matters concentration and visits for ophthalmoxerosis: A time-series analysis in a general hospital in Xuzhou, 2015—2019

Background Air pollution is one of the research hotspots in public health. Ophthalmoxerosis is an ocular surface disease with the highest incidence in this category, but its relationship with air particulate pollutants is still unclear.

Objective This study quantitatively estimates the associations of daily concentrations of ambient PM_2.5 and PM₁₀ with daily outpatient department visits due to ophthalmoxerosis in local residents in Xuzhou.

Methods Air pollutant variables, meteorological variables, and daily ophthalmoxerosis cases in a general hospital in Xuzhou were collected from 2015 to 2019. Poisson generalized additive models were applied. After controlling for confounding factors such as long-term trend, dayof-the-week effect, and meteorological factors, single pollutant models of daily concentrations of PM_2.5 and PM₁₀ of current day and lag 1-7 days in association with daily outpatient visits due to ophthalmoxerosis in local residents were constructed, and RRs and 95% CIs were calculated. Multi-pollutant models of PM_2.5 or PM₁₀ combined with gaseous pollutants (SO₂, NO₂, and O₃) on the day with the strongest effect were also established.

Results A total of 315 806 ophthalmoxerosis outpatient visits were included in this study, with a daily average of 173 cases. The Spearman correlation analysis results showed that PM₁₀ had the strongest correlation with PM_2.5 (r=0.90); PM_2.5 and PM₁₀ were both positively correlated with SO₂, NO₂, and relative humidity (P < 0.01) and negatively correlated with O₃ and average temperature (P < 0.01). The single pollutant models showed that a 10μg·m^-3 increase of PM_2.5 and PM₁₀ was associated with 0.46% (95%CI:0.38%-0.53%) and 0.43% (95% CI:0.35%-0.51%) increment respectively for the hospital visits due to ophthalmoxerosis of current day. The effects of PM_2.5 and PM₁₀ of lag 4 days were strongest, the excess relative risks were 0.66% (95% CI:0.61%-0.72%) and 0.69% (95% CI:0.62%-0.76%), respectively. In the multi-pollutant models, after adjusting for other pollutants, the estimated values of PM_2.5 and PM₁₀ were lower than those in the single pollutant models, and there were still positive correlations of PM_2.5 and PM₁₀ daily concentrations with daily outpatient volume of ophthalmoxerosis.

Conclusion The ambient PM_2.5 and PM₁₀ are in positive association with hospital visits due to ophthalmoxerosis in Xuzhou.