<p>Current understanding of how airborne particulate pollutants of varying sizes and their chemical constituents relate to conjunctivitis is limited. The aim of this study was to examine the relationship between daily exposure to particulate pollution and conjunctivitis in southeastern coastal China from 2013 to 2023. Data were collected from ten cities on conjunctivitis outpatient visits, air pollution levels, and meteorological conditions. We used conditional logistic regression models to estimate the city-specific effects of particulate matter (PM) of varying diameters (PM_2.5, PM_c, PM₁₀) and five major chemical constituents of PM_2.5 [black carbon (BC), ammonium (NH₄⁺), nitrate (NO₃⁻), sulfate (SO₄²⁻), and organic matter (OM)] on conjunctivitis outpatient visits. Overall estimates were derived through a meta-analysis. A total of 1,023,905 conjunctivitis outpatient visits were included. For each 10&#xa0;µg/m³ increment in daily mean levels of PM_2.5, PM_c, PM₁₀, BC, OM, SO₄²⁻, NO₃⁻, and NH₄⁺, the risk of conjunctivitis increased by 0.5%, 0.7%, 0.4%, 16.0%, 3.1%, 2.6%, 2.1%, and 3.5%, respectively. These associations did not differ significantly by sex, but were stronger in children under 6 years old (OR = 1.008, 95% CI: 1.003 to 1.013 for PM) and more notable in the warm season (OR = 1.007, 95% CI: 1.003 to 1.012 for PM). In conclusion, our results suggest a link between both the particle size and chemical composition of PM and conjunctivitis. This finding underscores the necessity of directing pollution control efforts specifically towards the most harmful particle sizes and components to prevent conjunctivitis.</p>