Occupational Health Risk Assessment of Microbiological Air Quality in Buhemba Small Scale Gold Mines, Tanzania

A large part of bio-aerosols is composed of biological particles such as bacteria, fungi, viruses, pollens, and their by-products such as endotoxins, metabolites, toxins, and other microbial fragments. These micro-organisms may affect human health with a wide range of adverse health effects including respiratory infections, allergies or toxic response in some individuals, especially susceptible ones. A cross-sectional study was conducted among purposely selected mining pits of Buhemba gold mine in Mara, Tanzania. To determine the microbial count, an agar strip loaded RCS® Microbial Air Sampler was used. Samples were collected at different microenvironments of the mining pit at a flow rate of 100 L min–1 for 5 minutes to yield a sample volume of 500 liters. Morphological characterization of both bacterial and fungal colonies was carried out followed by microscopic examination of fungal and gram-stained bacterial colonies. Regression analysis between mean bacterial and fungal spore counts with environmental factors like temperature and relative humidity was performed. The total aerobic bacteria concentration varied significantly (p value<0.05) between sampled pits (n=15), with the highest and lowest values of 3859 CFU/m3 and 1309 CFU/m3, respectively. However, there was no significant difference in total anaerobic bacteria concentration between sampled pits. The highest and lowest values of anaerobic bacteria were respectively 4284 CFU/m3 and 1190 CFU/m3. The highest and lowest values of total fungi concentration were 3314 CFU/m3 and 646 CFU/m3, respectively. High bacteria load that exceeds 1000 CFU/m3 as recommended by WHO was found in Buhemba gold mine.