Relationship between Air Pollution and Outpatient Visits for Nonspecific Conjunctivitis

PURPOSE. Past studies present evidence of associations between air pollution and human ocular symptoms; however, to the knowledge of the authors, research investigating the hazardous effects of air pollution on nonspecific conjunctivitis is nonexistent. This study investigates the relationship between air pollution and outpatient visits for nonspecific conjunctivitis in Taiwan. A multiarea analysis was conducted to examine and assess the risks of short-term effects of particulate matter (PM), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O-3), and carbon monoxide on nonspecific conjunctivitis. METHODS. Data were collected from outpatient visits for nonspecific conjunctivitis from seven air-quality-monitoring areas. To find immediate and lag effects of air pollution, an area-specific, case-crossover analysis was performed and a meta-analysis with random effects was used to combine the area-specific results. RESULTS. The effects on outpatient visits for nonspecific conjunctivitis are strongest for O-3 and NO2, with a 2.5% increase (95% confidence interval [CI], 0.9-4.1) for a 16.4 ppb (parts per billion) concentration rise in O-3 and a 2.3% increase (95% CI, 0.7-3.9) for an 11.47 ppb concentration rise in NO2. Effects are also found for particulate matter with an aerodynamic diameter <= 10 mu m (PM10) and SO2. Effects are more prominent in winter because the analysis was stratified according to season. CONCLUSIONS. The air pollutants NO2, SO2, O-3, and PM10 increase the chances of outpatient visits for nonspecific conjunctivitis and have no evident lag effects. (Invest Ophthalmol Vis Sci. 2012; 53: 429-433) DOI:10.1167/iovs.11-8253