Impact of fine particulate matter (PM2.5) on ocular health among people living in Chiang Mai, Thailand

Considering the limited information on the impact of PM_2.5 content on ocular health, a follow-up study was conducted on 50 healthy adults. Samples were collected twice, once before the PM_2.5 exposure season and again after exposure. Daily PM_2.5 concentration data was gathered from Thung Satok monitoring station. All subjects completed the self-structured ocular symptom questionnaire. The concentrations of 1-OHP were determined using HPLC-FLD. Logistic regression analysis investigated the relationship between PM_2.5 toxicity and ocular symptoms. The findings revealed that daily PM_2.5 concentrations surpassed the WHO-recommended range by around threefold. Exposure to PM_2.5 significantly raised the likelihood of ocular redness (adjusted OR: 12.39, 95% CI), watering (adjusted OR: 2.56, 95% CI), and dryness (adjusted OR: 5.06, 95% CI). Additionally, these symptoms had an exposure-response relationship with increasing 1-OHP levels. Ocular symptoms worsened in frequency and severity during the high PM_2.5 season, showing a strong link to elevated PM_2.5 levels. Lymphocyte counts were also positively correlated with redness, watering, and dryness during high PM_2.5 exposure. In conclusion, our study shows that subjects exposed to higher PM_2.5 levels presented more significant ocular surface alterations.