Abstract
Purpose:
Exposure to particulate matter less than 2.5 μm in aerodynamic diameter (PM2.5) was associated with increasing severity of asthma and respiratory symptoms; however, little is known about the effect of PM2.5 with allergic conjunctivitis. The purpose of this study is to examine the associations of PM2.5 on the daily clinical visits for allergic conjunctivitis.
Methods:
We conducted a time-series analysis of associations between outpatient visits for allergic conjunctivitis and PM2.5 concentrations during May to July (non-pollen season) and August to October 2012 (autumnal pollen season). Air pollution data including PM2.5, oxidant, nitric oxide, nitrogen dioxide, nitrogen oxide, carbon monoxide, methane, non-methane hydrocarbons, and total hydrocarbons, and daily weather conditions (temperatures, wind speed and humidity) were collected at a centrally located monitor in Tokyo. We calculated weekly averages for the daily number of outpatient visits and data of air pollution and weather conditions and used the weekly average data for the analysis.
Results:
The only significant association obtained was between outpatient visits for allergic conjunctivitis and the concentration of PM2.5 (r=0.62, p=0.0177) during May to July, while, no correlation was found between the number of outpatients and any variables of air conditions during August to November. Multivariate analysis also showed that significant predictor of the number of outpatients was the concentration of PM2.5 during May to July (odds ratio=9.05, p=0.0463), while there were no significant predictors of the number of outpatients during August to October. During May to July, PM2.5 was negatively correlated with humidity (r=-0.53, p=0.0499).
Conclusions:
These results suggest a possible role for PM2.5 in the development of allergic conjunctivitis during non-pollen season. Moreover, the observed association between PM2.5 and allergic conjunctivitis has a broad public health impact on allergic diseases.
Keywords: 475 conjunctivitis