Human exposure to PM2.5 at selected densely populated traffic sites in Accra, Ghana; A critical review

Road traffic emissions contribute substantially to air pollution. This is pronounced in developing cities experiencing fast growth and industrialization due to the increasing number of poorly maintained vehicles, poor fuel quality, and the importation of overaged vehicles. There is strong evidence connecting vehicle emissions exposure to a host of harmful health outcomes, such as cardiovascular and respiratory disorders. However, limited studies in Ghana have evaluated human exposure to PM2.5 pollution at traffic hotspots. The study systematically reviewed literature published between 2005 and 2022 to examine PM2.5 exposure trend and health effects at traffic areas in Accra neighbourhoods of varying socioeconomic status (SES). Literature searches were conducted in Scopus, PubMed, Web of Science, Google Advance Search and Google Scholar. A total of 30 empirical studies categorized into three groups based on population, land-use and socio-economic status were analyzed. One-way ANOVA showed that PM2.5 concentrations differed significantly by traffic site type, with notable effect observed (F = 4.78, p = 0.022). The study observed an annual mean (PM2.5) of 61.3 μg/m3, which is higher than the WHO and USEPA annual guideline values of 5 and 9 μg/m3, respectively, by a ratio of 12.3 and 6.8 times. This puts the urban population, especially those who travel regularly, work, or live at traffic hotspots or roadways, at serious health risk due to high exposure. Promotion of fuel and vehicle emission standards, regular monitoring, public education and awareness creation will help improve urban air quality.