Air Quality Impact from Petroleum Refinery at Sapugaskanda, Sri Lanka

Sapugaskanda Oil Refinery, the largest in Sri Lanka, is situated in a mixed land-use area and necessitates an investigation into its potential impacts on ambient air quality in the surround-ing region. This study aims to assess the concentrations of sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), ozone (O₃), and particulate matter (PM_2.5 and PM₁₀) near the Sapu-gaskanda Oil Refinery during normal operations and major shutdowns in 2018. It seeks to identify compliance issues with regulated limits and explore the effects of refinery activity on pollutant levels. Active monitoring results indicated no statistically significant differences in the concentrations of SO₂ (W=8, p=0.094), NO₂ (W=11, p=0.062), and O₃ (W=7.5, p=0.125) between normal operation and shut-down periods of the Sapugaskanda Oil Refinery for Wilcoxon Signed Rankings Test. PM_2.5 and PM₁₀ concentrations were higher during shutdowns (W=1, p=0.031). However, weather conditions varied between monitoring periods and may have influenced particulate matter concentrations. Measured pollutant concentrations were below the ambient air quality standards set by the Sri Lankan Ministry of Environment. Passive monitoring revealed no statistically significant spatial or temporal variation in SO₂ and NO₂ concentrations. However, long-term monitoring could help identify pollution hotspots and inform appropriate action plans in areas where industrial and urban pollution coexist.