Assessment of Dust Fall and Air Quality at Quarrying Sites in Plateau State

This study assesses dust fall rates and ambient air quality in communities adjacent to granite quarrying operations on the Jos Plateau in Plateau State, North Central Nigeria. Quarrying activities generate large quantities of airborne mineral dust from drilling, blasting, crushing, and transport operations, and communities near quarries may experience elevated exposures to respirable quartz and crystalline silica particles linked to silicosis and other respiratory diseases. Dust fall measurement using British Standard deposit gauges was conducted at eight stations surrounding three active quarry sites, while PM10 and PM2.5 concentrations were measured with calibrated optical monitors at the same stations. Respirable silica content was determined on selected filter samples by X-ray powder diffraction analysis. Wind roses were constructed from meteorological data to characterise the predominant particle transport directions. Dust fall rates at the nearest downwind community stations reach 180 grams per square metre per month, far exceeding the standard of 150 grams per square metre per month for residential areas. PM10 at downwind stations during active blasting periods exceeds 400 micrograms per cubic metre. Respirable silica content of fine fraction dust averages 22 percent, consistent with the geological composition of the Jos Plateau granite. Dust deposition on agricultural crops and domestic rainwater collection systems is cited as a community concern. The study recommends wet dust suppression at crushing and loading points, enclosed conveyor systems, and regular respiratory health monitoring of quarry workers. Keywords: quarry dust, silica, air quality, Plateau State, dust fall.