Analysis of particulate matter (PM) PM2.5 and PM10 was done around a cement company in Rivers State, Nigeria. Measurements were taken for the concentration of PM2.5 and PM10 and other atmospheric parameters at intervals of 100 m up to 1000 m and field observation was carried out for two days. The temperature of the area varied between 26.6 degrees and 33.3 degrees, relative humidity was between 70.2 and 98.2% and the wind speed ranged from 0.2 to 3.6 m/s. The minimum PM10 and PM2.5 values were 38 and 18 µg/m3 respectively and the maximum PM10 and PM2.5 values were 616 and 298 µg/m3 respectively. A two way analysis of variance was done at 5 % level of significance to determine the influence the time the measurement was taken and the distance from the stack have on the particulate matter concentration. P values were lower than P = .05 therefore, the null hypothesis was rejected. The pollution index for PM10 was determined and about 86% of the pollution index are above 100, 80% are above 150 and about 21% is above 400. About 96% of the pollution index for PM2.5 is above 100, 87% are above 150 and about 21% are above 300. As shown on Air quality index charts, values between 100 and 150 are unhealthy for sensitive groups, values above 150 are unhealthy, and values above 300 are hazardous while values above 400 are very hazardous. It is concluded that the ground level concentration of PM10 and PM2.5 up to 1200 m from the stack is generally unhealthy for the receptors.