Diurnal Rhythms of Ambient Air Pollution Due to Vehicular Traffic in Accra

ABSTRACT

Background: Air pollution has become one of the most serious environmental concerns in cities throughout the world – especially in developing countries. Increase in human and vehicular population has left many streets of developing countries with high levels of congestion and an indiscriminate release of vehicular exhaust emissions polluting ambient air flow and exposing populations to severe health outcomes.

Objective: The aim of this study was to determine the diurnal rhythms of ambient air pollution due to vehicular traffic in Accra.

Methods: The study was a quantitative cross-sectional study which was conducted on five (5) routes. The routes included four (4) major intersections at the Accra-Madina-Adenta route, Kaneshie-Mallam-Kasoa route, Achimota-Pokuase-Ofankor route and the Accra-Tema motorway. The fifth route was on Legon campus specifically on the Limann-Jean Nelson Aka route. Aeroqual 500 series monitors (Aeroqual Limited., Auckland, New Zealand) was used to sample air pollutants; VOCs, CO, SO2 and NO2 at specific spots on the respective routes. A GPS was also used to pick the coordinates of each spot on the five routes.  GIS version 10 was used to develop maps for the routes. The study was conducted in eight (8) days within a period of 10 hours on each route. Statistical analyses was done with STATA software version 10 (StataCorps LP, Chicago, USA).

Results: Overall, except for NO2, which had a mean concentration of, (0.10 ppm), the mean concentrations of air pollutants; VOCs (0.16 ppm), CO (2.46 ppm), SO2 (0.12 ppm) were higher than the acceptable reference values set by the WHO in its air quality guidelines; VOCs (0.02 ppm), CO (0.09), SO2 (0.175 ppm), NO2 (0.10 ppm). 

Conclusion: Except for NO2, the average concentrations of air pollutants (VOCs, CO and SO2) were higher than WHO acceptable levels or standards, which could negatively impact on human health.