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

Considering the limited information on the impact of PM content on ocular health, a follow-up study was conducted on 50 healthy adults. Samples were collected twice, once before the PM exposure season and again after exposure. Daily PM 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 toxicity and ocular symptoms. The findings revealed that daily PM concentrations surpassed the WHO-recommended range by around threefold. Exposure to PM 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 season, showing a strong link to elevated PM levels. Lymphocyte counts were also positively correlated with redness, watering, and dryness during high PM exposure. In conclusion, our study shows that subjects exposed to higher PM levels presented more significant ocular surface alterations.