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 (O₃), 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 O₃ 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 O₃ 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 μm (PM₁₀) and SO₂. Effects are more prominent in winter because the analysis was stratified according to season. CONCLUSIONS: The air pollutants NO₂, SO₂, O₃, and PM₁₀ increase the chances of outpatient visits for nonspecific conjunctivitis and have no evident lag effects.