Spatiotemporal Inventory of Vehicular Emissions Along the Benin-Ore-Sagamu Highway Using Emission Factor Approach

In response to growing public health concerns regarding elevated exposure to traffic-related air pollutants and their associated adverse health effects in populations residing near major roadways, it is imperative to assess the environmental impacts of vehicular emissions as a basis for implementing effective mitigation strategies. This study employed the emission factor approach to assess how different vehicle types contribute to air pollution, specifically CO, SO₂, VOCs, PM, and CO₂, at the four traffic-congested intersections along the Benin-Ore-Sagamu highway in southwestern Nigeria. The selected sites (Okada Junction, Ore, Ijebu-Ode, and Sagamu) are key locations for analyzing the impact of vehicular emissions on air quality. Manual vehicle counts were conducted daily over one month to estimate the annual traffic volume. The recorded traffic data were integrated with pollutant-specific emission factors and the annual fuel consumption of the various vehicle categories to compute the corresponding emission rates for each air pollutant. The findings revealed that estimated annual emissions of carbon monoxide (CO), sulphur dioxide (SO₂), volatile organic compounds (VOCs), particulate matter (PM), and carbon dioxide (CO₂) ranged from 74,740 to 95,579 tons/year, 6,940 to 9,228 tons/year, 7,590 to 9,470 tons/year, 690 to 910 tons/year, and 546,000 to 744,000 tons/year, respectively. Gasoline-powered vehicles accounted for approximately 60% to 90% of total VOCs and CO emissions, whereas diesel-powered vehicles contributed between 80% and 90% of SO₂ and PM emissions. To reduce vehicular emissions, the study recommends a multifaceted approach involving stricter regulations, cleaner fuels, vehicle emission standards, and public awareness campaigns.