ABSTRACT
The mass concentration and size distribution of atmospheric particulate matter (PM) was measured in three major towns in Plateau state. The CW-HAT200 PM2.5, PM10 dust particle counter was used to measure the particle size in each major location within Jos, Shendam and Pankshin. The results revealed that both PM2.5 and PM10 concentration were high in morning hours in most of the measured locations. These values were however found decreasing in the afternoon. The higher value of PM2.5 and PM10 observed in the morning hours in some locations within the study area can be attributed to the high volume of motorists plying the roads during those hours. However, some locations within the study area their PM2.5 and PM10 were higher in the afternoon hours than morning hours. The PM sampling respirable dust sampler (AMP460NL model) was placed on the elevated platform of 1.5 m high and 20 cm away from obstacles in order to avoid any obstruction of the air from tall buildings and trees etc. Measurements were taken after 8-hours per location and the average air flow rate, sample time, initial and final mass of the filter paper were used to calculate the mass concentration of the suspended particulate matter in each locations. The mass concentration of the suspended particulate matter were higher in dry season than in the rain season for all locations. This can be attributed to the dust usually experienced during the dry season on the Plateau.