Outdoor Air Pollution and Pterygium in Korea

Abstract

We investigated relationships between outdoor air pollution and pterygium in Korean adults. This study includes 23,276 adults in population-based cross-sectional data using the Korea National Health and Nutrition Examination Survey 2008-2011. Pterygium was assessed using slit lamp biomicroscopy. Air pollution data (humidity, particulate matter with aerodynamic diameter less than 10 μm [PM₁₀], ozone [O₃], nitrogen dioxide [NO₂], and sulfur dioxide levels [SO₂]) for 2 years preceding the ocular examinations were acquired. Associations of multiple air pollutants with pterygium or pterygium recurrence after surgery were examined using multivariate logistic models, after adjusting for several covariates. Distributed lag models were additionally used for estimating cumulative effects of air pollution on pterygium. None of air pollution factors was significantly associated with pterygium or pterygium recurrence (each P > 0.05). Distributed lag models also showed that air pollution factors were not associated with pterygium or pterygium recurrence in 0-to-2 year lags (each P > 0.05). However, primary pterygium showed a weak association with PM10 after adjusting for covariates (odds ratio [OR] 1.23; [per 5 μg/m³ PM₁₀ increase]; P = 0.023). Aging, male sex, and greater sun exposure were associated with pterygium, while higher education level and myopia were negatively associated with pterygium (each P ≤ 0.001). Male sex and myopia were negatively associated with pterygium recurrence (each P < 0.05). In conclusion, exposure to higher PM10 levels was associated with primary pterygium, although this study observed no significant association between air pollution and overall pterygium or pterygium recurrence in Korean adults.

Keywords: Air Pollution; Association; PM₁₀; Pterygium; Recurrence.

Fig. 1

Flow diagram presenting the selection of study participants. KNHANES = Korea National Health and Nutrition Examination Survey.

Fig. 2

Distributed lag models between outdoor air pollutants (humidity, PM, O₃, NO₂, and SO₂) and pterygium. (A) Model 1, (B) Model 2. Model 1: sociodemographic factors were included as covariates; Model 2: sociodemographic factors, sun exposure, and myopia were included as covariates. PM₁₀ = particulate matter with aerodynamic diameter less than 10 µm, O₃ = ozone, NO₂ = nitrogen dioxide, SO₂ = sulfur dioxide, OR = odds ratio, CI = confidence interval.

Fig. 3

Distributed lag models between PM and primary pterygium. (A) Model 1, (B) Model 2. Model 1: sociodemographic factors were included as covariates; Model 2: sociodemographic factors, sun exposure, and myopia were included as covariates. PM₁₀ = particulate matter with aerodynamic diameter less than 10 µm, OR = odds ratio, CI = confidence interval. ^*Associated with primary pterygium in multivariate logistic regression.