An Evaluation of Atmospheric Aerosols in Kanana, Klerksdorp Gold Mining Town, in the North-West Province of South Africa

Abstract

Atmospheric aerosols have posed a health challenge by their presence in the atmosphere. In order to control them, they have to be understood in terms of their interactions in the air, their length of suspension and their transportation. It is true to say aerosols have been in the atmosphere since the beginning of time itself. As long as there has been wind, particulate matter has found itself in the air, attributed to nature aerosol emissions. Atmospheric aerosols technically are considered to be suspension of fine solid or liquid particles in a gas (Hinds, 1999). Particles in the air can change their size and composition by condensation of vapour species or evaporation, coagulating with other particles by chemical reaction, or by activation in the presence of water. The production of atmospheric aerosols or atmospheric particulate matter is of great concern. The effects of inhaling particulate matter which have been widely studied in humans and animals include asthma, lung cancer, cardiovascular issues, and premature death (Pope & Burnett, 2002). The size of the particle is a main determinant of where in the respiratory tract the particle will come to rest when inhaled. Larger particles are generally filtered in the nose and throat and do not necessarily cause problems, but particulate matter smaller than about 10 micrometers (μm), referred to as PM10, can settle in the bronchi and lungs and cause health problems. The 10 micrometer (μm) particle size does not represent a strict boundary between respirable and non-respirable particles, but has been agreed upon for monitoring of airborne particulate matter by most regulatory agencies (Seinfeld & Pandis, 2006). Similarly, particles smaller than 2.5 micrometers, PM2.5, tend to penetrate into the gas-exchange regions of the lung, and very small particles (< 100 nanometers) may pass through the lungs to affect other organs. PM2.5 leads to high plaque deposits in arteries, causing vascular inflammation and atherosclerosis — a hardening of the arteries that reduces elasticity, which can lead to heart attacks and other cardiovascular problems (Pope & Burnett, 2002). Airborne particles undergo various physical and chemical interactions and transformation (i.e. atmospheric aging), changes of particle size, structure, and composition (coagulation, restructuring, gas uptake, chemical reaction). Particularly efficient particle aging occurs in clouds, which are formed by condensation of water vapour on pre-existing aerosol particles (cloud condensation and ice nuclei). Most clouds re-evaporate, and modified aerosol