The petrochemical industry produces many air pollutants during production, such as airborne particulate matters (PM10 and PM2.5), sulfur oxides, nitrogen oxides, volatile organic compounds, carbon oxides, etc. Petrochemical industrial accidents are more likely to cause major air pollution hazards in a short period. Therefore this study simulated diffusion and performed air pollution spatial risk analysis for potential air pollutants generated by the petrochemical industry using meteorological observation data from 2017 to 2019. The study targets were No. 6 Naphtha Cracker Complex Petrochemical Industrial Park (6NCC) of Formosa Petrochemical Corporation and Taichung Thermal Power Plant (TTPP) in central Taiwan. We used the industrial source complex model short term (ISCST3) air simulation model developed by the US Environmental Protection Agency to simulate pollutant diffusion under different weather conditions and seasons. Air pollution spatial risk was investigated for neighboring hospitals and schools for pollutant emission and diffusion to provide feedback to petrochemical related industry's risk management. Emission areas (6NCC and TTPP) were all in the southwest since the main air pollution accumulation and diffusion is to the northeast during monsoon season (October through March). Air pollution April through September each year is more evenly distributed, with pollutant concentrations low in all directions, approximately half the concentration in winter. Simulated air pollutant concentrations often overlapped with high risk population clusters (schools and hospitals). 6NCC posed little impact on nearby schools throughout the year; whereas TTPP posed relatively low risks to nearby schools and hospitals in summer, with slightly higher risk for Shenren Elementary School in Shengang township, Changhua County in winter. Overall 6NCC posed higher risk for Mailiao and Taixi townships in Yunlin County; whereas the TTPP posed higher risk on Longjing District of Taichung City, Shengang and Xianxi townships in Changhua County, particularly during winter. The results of this study will help the petrochemical industry and public health authority to wider manage air pollution risks.