1 Volume 2018; Issue 01 International Journal of Pollution Research Research Article Edokpa D, et al. Int J Pollut Res: IJPR-111. An Assessment of Ground Level Criteria Pollutant Concentrations in Port Harcourt City, Nigeria David Edokpa 1* , Bridget Diagi 2 and Peace Nwaerema 2 1 Department of Geography and Environmental Management, Rivers State University, Port Harcourt, Nigeria 2 Department of Geography and Environmental Management, University of Port Harcourt, Port Harcourt, Nigeria * Corresponding author: David Edokpa, Department of Geography and Environmental Management, Rivers State University, Port Harcourt, Nigeria. Tel: +234 803 3275677; Email: onojiede@gmail.com Citation: Edokpa D, Diagi B, Nwaerema P (2019) An Assessment of Ground Level Criteria Pollutant Concentrations in Port Har- court City, Nigeria. Int J Pollut Res: IJPR-111. DOI: 10.29011/IJPR -111.100011 Received Date: 30 August, 2019; Accepted Date: 29 October, 2019; Published Date: 01 November, 2019 Abstract This study evaluates the ground level concentrations of main criteria pollutants emitted from prevalent emission sources at 10 sampled locations in Port Harcourt city for peak dry and early wet seasons. Assessments were done within 3 hours per dual diurnal section using approved standard methods and converted to a 1-hour mean for the morning and evening period of sampling i.e. 6-9am and 5-8pm. These periods are the rush hours of peak human/traffc movements across the city. Results shows that during the peak dry season in January, pollutants concentrations ranged between 0.05-0.39 mg/m3; 1.02-21.22 mg/ m3; 3.1-31.3 µg/m3 and 15.2-257.7 µg/m3 for NOx, CO, PM2.5 and PM10 and for early wet season in April, it ranged between 0.06-0.28mg/m3; 1.02-22.67 mg/m3; 6.3-35.8µg/m3 and 14.2-201.4µg/m3 respectively. The air quality assessments show that NOx and PM10 were signifcant and above set limits for Nigeria (100-370% and 10-60%) during the dry season and sampled time frame except for the wet season when PM10 was below set limit for most of the sampled locations due to downwash of the suspended particulate by early rains. The concentration of PM2.5 was generally below set limit across the sampled locations for Nigeria and WHO (based on target 1) standards. Ground level concentrations of NOx and CO were above set limit for Nigeria at a sampled residential location during the morning rush hours while particulates were below set limits for the area. The air quality was best at Port Harcourt international airport as pollutant concentrations were generally below set limit. There is need for nonstop surveillance of ground level emission concentrations most especially around the city centre to guarantee the protection and well-being of the environment and the city dwellers. DOI: 10.29011/IJPR -111.100011 Keywords: Air pollution; Boundary layer; Carbon monoxide; Oxides of nitrogen; Particulates; Port Harcourt Introduction Anthropogenic activities resulting from human’s quest to generate returns for survival has alleviated the rate of pollutants emissions within the planetary boundary layer. At every moment various emission facilities releases pollutants into the local environment which affects the health and wellbeing of boundary layer dwellers [1]. Port Harcourt, a well-known city in Nigeria has been worst hit both in the past and recently due to multiple sources of emissions daily without any period of cessation. Exposures of living organisms including humans to these emissions can lead to short and long term injurious health effects [2], however, this does not seem to bother both the emitters and environmental regulators. This lack of sensitivity to environmental pollution in Nigeria has been attributed to the very low level of awareness of the people and policy makers [3]. The most common air pollutants release within cities includes Suspended Particulate Matter of various sizes (SPM), Oxides of Nitrogen (NO x ), Sulphur Dioxides (SO x ), Carbon Monoxide (CO) etc., and these pollutants can be in form of solid particles, liquid droplets or gases [4]. Air pollutants can be primary or secondary and also classifed according to space of their effects i.e. local, regional and global [5]. Primary pollutants’ such as NOx, CO, SPM, etc. are released from the original sources while secondary contaminants are those generated in the atmosphere by chemical reactions and include: ozone (O 3 ), other photochemical oxidants – Peroxyacetyl Nitrates (PAN), and oxidised hydrocarbons etc. According to the estimates by the World Health Organisation (WHO), about seven million fatalities have taken place due to the