Impact Assessment of Particulate Pollutants in Selected Traffic Congested Areas in Zaria Metropolis, Kaduna State, Nigeria

It has been noticed that the concentration of particle pollutants in major nodal points in Zaria metropolis has continued to grow as the traffic volume increases. The concentration of particulate matter and meteorological data was measured within the Zaria metropolis and was limited to major ways within the town which include Kwangila, PZ, Kasua Mata, Agoro and Kofar Doka. The concentrations of the Particulate Matter in different particle sizes (P_0.3, P_0.5.P_1.0, P_2.5 and P_5.0) were measured using particle counter, at each sampling point for 3hrs during the morning peak hours (7:00am to 10.00am), for 3hrs during the afternoon off peak hours (11.00am to 2:00pm) and for 3hrs for the evening peak hours (4:00 to 7:00pm) after a comprehensive traffic volume of vehicles plying the sampling points had been done for one month. The average traffic volume for the peak period (morning) across the five sampling points ranged from 2701-3060 while that of the evening peak hours ranged from 2676-3651. The average traffic volume for the off peak (afternoon) ranged from 1777-2255 with kwangila recording the highest traffic volume for both peak and off peak periods. The impact of traffic density on the concentration of particulate matter measured showed that increase in traffic led to a corresponding increase in the concentration of particulate matter recorded for both peak and off- peak periods. The P_2.5 was used as bases for comparison with the AQI standard for peak and off peak periods. For peak hour session, the air quality at Kwangila, Kasua Mata and Agoro was classified as unhealthy and hazardous while that of PZ and Kofar Doka was classified unhealthy to people with heart and lungs diseases. The concentration of PM obtained for off-peak period for all the sampling points was classified moderate and safe when compared with AQI standard. In this regard, there is a need to not only promote public transportation with larger capacity of passengers but to also improve the public transportation system. This will reduce greenhouse gas emissions by providing a convenient option to reduce unnecessary driving and by lowering emissions per passenger kilometer travelled. The use of non-motorized means of transportation would also help in curbing excessive release of pollutants into the atmosphere. Planting of Trees along major ways to trap and absorb pollutants is another option of reducing the amount of pollutants in the atmosphere. The use of older vehicles should be discouraged. The older a vehicle is the more the tendency to emit more pollutants.