Professional Assessment of Environmental Monitoring Networks for Air Quality Management in Lagos Megacity

This study conducts a professional assessment of the adequacy and effectiveness of the ambient air quality monitoring network in Lagos, South West Nigeria, examining whether the existing monitoring infrastructure provides sufficient spatial and temporal coverage to support evidence-based air quality management in Africa's largest urban agglomeration. Lagos faces severe air quality challenges from vehicular emissions, industrial sources, open waste burning, and generator exhaust, and effective management of these sources requires a robust monitoring network that accurately characterises population exposure and tracks compliance with national standards. The assessment evaluates the current Lagos State Environment Protection Agency monitoring network of five fixed monitoring stations against internationally recommended network design criteria using WHO guidance and the United States EPA monitoring network design framework. Criteria assessed include station siting, spatial representativeness, pollutant coverage, data availability rates, quality assurance procedures, and data dissemination to the public. The assessment is supplemented by analysis of available continuous monitoring data from 2021 to 2023 for PM2.5, ozone, nitrogen dioxide, and carbon monoxide. Findings reveal that five stations are grossly inadequate for a megacity with population exceeding fifteen million, providing no representation for significant portions of the metropolitan area. Data availability rates are low at 62 percent on average due to power supply interruptions at monitoring stations. Quality assurance documentation is incomplete. The study recommends a network expansion plan to a minimum of twenty-five stations with backup power supply and real-time data publication. Keywords: air quality monitoring, network design, Lagos, ambient monitoring, urban air pollution.