Air pollutants and their concentration levels were measured at forty sampling stations within the study area. Detailed Air quality analysis was carried out. mean CO was 12.31ppm in the dry season and 5.27ppm in the wet season; mean TSP was 376.7µg/m3 in the dry season and 464.9µg/m3 and in the wet season; mean PM10 was 263.3µg/m3 in the dry season and 313.1µg/m3 in the wet season; mean PM2.5 was 68.7µg/m3 in the dry season and 62.2µg/m3 in the wet season. Sulphur dioxide, nitrogen dioxide, and particulate matter exceeded stipulated NAAQS limits and pose a greater risk to public health.  Onitsha Main Market and Central Part were the hotspots of particulate matter. Onitsha Main Market, Bridgehead, and Awada Layout are the worst affected by particulate pollution. Most people in the Onitsha metropolis are exposed to hazardous air quality in the dry season and unhealthy air quality in the wet season; respiratory, lung, and heart diseases may be prevalent in the study area. Health impact assessment should be conducted in Onitsha metropolis, residents should go for regular medical check-ups; air quality monitoring stations should be established around Onitsha metropolis. State government should enforce compliance laws and regulate the activities of industries in the areas.

Keywords: industries, Air Pollutants, pollution, State government