Geospatial Distribution of Air Pollutants Along Selected Traffic Routes Within Port Harcourt Metropolis

ABSTRACT

The study investigates the spatial distribution and concentration of air pollutants (mainly from automobile emission) at traffic intersections at selected major routes within Port-Harcourt Metropolis, Rivers State, Nigeria. Five sampling locations (using purposive sampling technique in selecting the sampling locations) were considered which are Rumuokoro, Rumuola, Garrison, UST/Mile 3 and Mile 1, with each having three sampling points placed 2.0m away from the edge of the road and sampling equipment placed at 1.5m above ground-level, assumed to be the average height of human capable of inhaling the air pollutants. Priority air parameters: CO, SO2, NO2, H2S and SPM were monitored at the sampling locations/sites both in the morning and afternoon. The recorded highest mean concentrations of CO, SO2, NO2, H2S and SPM are 1485.8 µg/m3 , 104.5 µg/m3 , 37.6 µg/m3 , 27.8 µg/m3 and 2.85 µg/m3 x 10^1 respectively. Generally, the highest level of concentration obtained for the air pollution indicator, CO was at Rumuola due to traffic congestion and traffic intersection, where long waiting time for vehicles was observed and thus far exceeding DPR and NAAQS air quality standard. An increasing trend of NO2 was observed at the Northern (Rumukoro) and Southern (Mile 1) part of the city. Moreover, the concentration levels of nitrogen dioxide are below the DPR and NAAQS air quality standard within the study area. The SO2mean concentration in all the sampling points/locations were in the mean range of 0.090-104.4µg/m3 , the highest value was found at northern part (Rumukoro) of the study area. All the five monitored air pollutants when compared with AQI level (Air quality index) in all sampling location. It was observed that SO2 was moderate, NO2 was good and CO was very unhealthy in all the locations. The study revealed that pollution at traffic intersection is threatening and that motor vehicle forms the dominant source of urban air pollution. In conclusion, it is quite important to understand the role of mobile source emissions play on air quality. It is recommended that vehicle emission standards be strongly enforced. Alternative or eco-friendly technology such as the use of solar energy/electric cars be considered as future means of transportation and also the implementation of Smart-City concept in urban/land-use and transportation planning.