Estimation of air aerosol number concentration by indirect method

The estimation of the air aerosol number concentration variation was carried out in this work making use of data obtained from the Bauchi Road Campus of the University of Jos, Plateau State, Nigeria in 1990. The aerosol number concentration was determined indirectly, making use of the intensity of light scattered by particles. The scattered light intensity is proportional to the average number concentration of the aerosols, averaged during a 7 day sampling period for 3½ h per day from 1200 to 1530 h if the aerosols are in motion. The dimensionless ratio of the voltages V1/V2 is proportional to the average aerosol number concentration. From the line of regressions, it becomes obvious that the measured and estimated aerosol number concentrations increases linearly with time over the period of measurement. The slopes, 0.0232 and 0.0233 of the regression lines for the measured and estimated number concentrations respectively are proportional to the rates at which the aerosols concentrations varied with time in the environment.    Key words: Aerosol, estimated number concentration, concentration, indirect method.