RISK ASSESSMENT OF TOXICITY POTENTIAL FOR CRITERIA AMBIENT AIR POLLUTANTS IN SELECTED AREAS OF LAGOS STATE, NIGERIA

Abstract

The quality of ambient air is determined by the extent of pollution of the environment. The United States Environmental
Protection Agency identifies six pollutants namely particulate matter, ground level ozone, carbon monoxide, sulphur oxides, nitrogen oxides and lead exposure as toxic and injurious because of their potentials to cause or trigger various human health problems. This study examines the toxicity potential of criteria ambient air pollutants in selected areas of Lagos State, Nigeria. The data for the study include five-year data of criteria pollutants for selected areas of Lagos and World Health Organization (WHO) guideline values of criteria pollutants. Data analysis adopted the use of Toxicity Potential Model for the calculation of the toxicity potential of the criteria pollutants. GIS procedure was employed to produce a map showing the spatial pattern and hotspot areas of criteria pollutants. Criteria pollutants in the study area were also compared with the WHO standards with a view to determining areas of excessive pollution and toxicity potential in the area. The study reveals that PM , PM SO and NO in Lagos areas clearly exceeded the benchmark set by WHO. Furthermore, CO and O are well below the WHO standards. The toxicity potential values for PM , PM SO and NO in the area of study are greater than unity while the values for CO and O are lesser than unity which indicates that such concentration has a tendency of causing
harm to people and hence should be avoided. The study recommends that governments, and other stakeholders in health should harmonize efforts, resources and ideas towards effective planning, monitoring, and provision of facilities that could control and ameliorate the presence of these pollutants to which urban residents are exposed thereby reducing the health
effects from such exposures.