ASSESSMENT OF PARTICULATE MATTER EXPOSURE ON AMBIENT AIR AND ITS IMPACT ON WORKERS HEALTH AT TWO GRANITE QUARRY MINES

Abstract

Particulate matter (PM) from quarrying activities is among the major sources of pollution in ambient air. Apart from affecting the environment, PM exposure is one of the leading causes of respiratory illnesses in the world. The current study, unique to Malawi, was aimed at determining the impact of particulate matter on ambient air quality, and the possible effects on the health of workers at Njuli, Terrastone mine in Chiradzulu and Mota Engil mine in Blantyre districts. The study measured concentrations of particulate matter in ambient air, conducted chemical analysis of fallen dust, and carried out a survey on respiratory symptoms. Results showed higher exposures to particulate matter at Terrastone mine (126µg/m 3 highest exposure) compared to Mota Engil mine (83 µg/m 3 highest exposure), and this was attributed to poor management practices at Terrastone mine. Higher PM readings (0- 85.98µg/m 3 ) were observed for sites located downwind of the mines than sites located upwind (0-59 µg/m 3 ), demonstrating the impact of quarrying operations at the mines. However, the readings at Terrastone and Mota Engil mines compared by site were not statistically significant P=0.0612 and P=0.686 respectively. The observed amount of PM in ambient air was consistent with the scale of quarrying and processing operations at both mines, 0-56.2 µg/m 3 in pre-operational phases, 0-126.1 µg/m 3 during operations and 0-56 µg/m 3 after closure of operations. The results showed significant difference among the phases of operations compared at Terrastone Mine only (P=0.045). Analysis of health symptoms revealed that a higher proportion of workers at Terrastone mine experienced respiratory symptoms compared to Mota Engil mine.