Air Quality in Nigerian Urban Environments: A Comprehensive Assessment of Gaseous Pollutants and Particle Concentrations

Abstract

The rise in gaseous pollutants and particulate concentrations is a serious problem for the environment. This study examined the air quality within four urban areas (Awka, Ekwulobia, Nnewi, and Onitsha) in Anambra State, Nigeria. The concentrations of known air pollutants including suspended particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), methane (CH4), volatile organic compounds (VOCs), hydrogen sulfide (H2S), ammonia (NH3), ozone (O3), carbon dioxide (CO2) and carbon monoxide (CO) were assessed at various locations within the study areas using Aeroqual air quality monitoring devices, and the results were compared with the WHO air quality guidelines for health impact assessment. The air quality index (AQI) was interpolated from the pollutant concentrations in order to show hazard categories of air quality conditions over the study locations. The mean concentrations of SO2, CH4, and VOCs within the residential locations of Awka, Ekwulobia, and Nnewi were in the range of 200-8000 µg m-3 and exceeded WHO limits for air quality. While the levels of CO2, SO2, and CH4 (3.25-1,027,000 µg m-3) within the commercial locations of Awka, Ekwulobia, and Nnewi exceeded WHO limits, only VOCs (500-1100 µg m-3) within Awka and Ekwulobia exceeded the limits. The 62-181 µg m-3 and 40-295 µg m-3 ranges of PM2.5 and PM10, respectively within the Nnewi and Ekwulobia commercial locations were the only particle concentrations at which the World Health Organization (WHO) recommended limits for health aspects of air pollution were exceeded. The AQI calculations showed air quality within some of the locations may have potential risks for public health.