Determination of the Variations in Air Quality Due to the Construction of the Atani–Obosi Second Niger Bridge Access Route: Assessment of Aerosol, Nitrogen Dioxide (No₂), Formaldehyde (Hcho), and Carbon Monoxide (Co)

Abstract

Transportation infrastructure projects are essential for socio-economic development but often generate environmental impacts that affect air quality and public health. This study assessed variations in air quality associated with the construction of the Atani–Obosi Access Route of the Second Niger Bridge with specific objectives of assessing temporal variations in Aerosol concentrations; determination of changes in Nitrogen Dioxide (NO₂), Formaldehyde (HCHO) and Carbon Monoxide (CO) concentrations between 2017 and 2024; and to examine the relationship between transportation activities and air-quality conditions. A geospatial and environmental monitoring approach integrating remotely sensed atmospheric datasets, Geographic Information Systems (GIS), and statistical analysis was employed to evaluate spatial and temporal changes in atmospheric conditions during the pre-construction, construction, and post-construction phases of the project. The results revealed significant increases in Aerosol, NO₂, HCHO, and CO concentrations during the construction phase, reflecting the impacts of vegetation clearance, earthworks, material transportation, operation of heavy-duty equipment, and increased vehicular activities. Aerosol concentrations exhibited the most pronounced fluctuations during intensive construction activities, while NO₂ and CO concentrations showed strong associations with traffic intensity and fuel combustion processes. Formaldehyde concentrations similarly increased during project implementation, indicating enhanced atmospheric emissions from anthropogenic sources. Although pollutant levels declined following project completion, post-construction concentrations remained higher than pre-construction conditions. Multiple Linear Regression analysis demonstrated significant relationships between traffic intensity and atmospheric pollutant concentrations, confirming the role of transportation infrastructure development in shaping local air quality dynamics. The findings indicate that while the access route has improved transportation efficiency and regional connectivity, its construction and operation have contributed to measurable deterioration in atmospheric quality. The study recommends continuous air-quality monitoring, incorporation of emission-control strategies, and integration of environmental safeguards into future transportation infrastructure projects