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.

This study examines how seasonal air pollution affects health perceptions, risk awareness, and preventive behaviors among a sample of 150 individuals, particularly within vulnerable people living in Thailand. Many participants were older adults (54.7% aged ≥ 60), female (76.7%), and had a low income (less than 10,000 THB/month (USD 295), 92.6%). Polycyclic Aromatic Hydrocarbon (PAH) exposure, as indicated by urinary 1-Hydroxypyrene (1-OHP), significantly increased during high-pollution periods (p < 0.001), while benzo[a]pyrene diol epoxide (BPDE) levels did not show significant changes. Farmers exhibited the highest PAH exposure (p = 0.018). Risk perception and preventive behavior scores rose from 0.711 to 0.748 and from 0.505 to 0.707, respectively. Notable items with high factor loadings included “burning pollutes the air and spreads pollution” (Q2.1 = 0.998) and “avoid burning of any kind” (Q4.2 = 1.007). Neurological symptoms, such as loss of consciousness, increased from 0.956 to 1.049, while respiratory problems like pneumonia went up from 0.673 to 1.07. Environmental risk knowledge-related perceptions experienced a slight decline (from 0.609 to 0.576). These results highlight the need for targeted education through community workshops and strategies like mask distribution, indoor air filtration, and early warning systems for vulnerable populations.