Assessment of PM₂.₅ related health impacts along a major traffic corridor in Lagos using the WHO AirQ⁺ model

Abstract

Air pollution from fine particulate matter (PM₂.₅) poses a significant environmental health challenge in rapidly urbanizing African cities. Lagos, Nigeria, experiences severe traffic congestion and elevated ambient PM₂.₅ concentrations, yet localized estimates of associated health impacts remain limited. This study applies the World Health Organization’s AirQ⁺ model to quantify mortality attributable to PM₂.₅ exposure along the Ikeja traffic corridor, a representative high-traffic urban environment. Ambient PM₂.₅ concentrations were monitored using a high-resolution SNAQ sensor over four months (November 2018–February 2019), yielding a mean concentration of 73.75 µg/m3 and peaks exceeding 123 µg/m3. Population data for Ikeja (≈475,000 residents) and cause-specific mortality rates from the Institute for Health Metrics and national statistics were used as model inputs. Using the study-period mean concentration, AirQ⁺ estimated that acute lower respiratory infections (ALRI) accounted for the largest number of attributable deaths over the four-month period (4,131; 520 per 100,000 population), while lung cancer (54.1%) and ischemic heart disease (50.8%) showed the highest attributable fractions. Weekly and monthly analyses revealed that even modest fluctuations in PM₂.₅ levels could meaningfully influence respiratory and cardiovascular mortality. Scenario analysis indicates that a 10% reduction in PM₂.₅ concentrations could prevent more than 1,400 premature deaths, highlighting the potential health benefits of targeted emission control and traffic management strategies. These findings underscore the substantial burden of traffic-related PM₂.₅ exposure in Lagos and provide critical evidence to guide urban air quality interventions and public health policy in rapidly developing African megacities.