Occupational area noise exposure in small-scale metal industry in Dar-es-Salaam, Tanzania

Noise exposure in the informal small-scale metal industry may cause hearing loss, due to metal manufacturing processes. In Tanzania, this industry uses hand tools in metal fabrication processes and is not regulated by authorities.

To describe noise exposure levels and to suggest possible improvements in the small-scale metal industry in Dar-es-Salaam, Tanzania.

The study was conducted in 3 small-scale metal industry cooperatives in Dar-es-Salaam, with self-employed workers. Noise levels were measured using a portable sound level meter (Brüel and Kjær type 2250). Data was analyzed using descriptive statistics and analysis of variance to compare noise levels. A walk-through survey and an interview were conducted to collect information on work operations and control measures.

The workers were seated close to one another in open rooms and produced continuous noise during the whole workday. No hearing protection or noise reduction strategies were observed. The average noise exposure level was 90.9 dBA, 106.9 dBA, and 89.7 dBA in the 3 metal companies X, Y, and Z, respectively, and the differences between companies were statistically significant. Company Y, with the highest noise level, had more workers. The average peak noise level was 124.6 dBA.

The studied workplaces had noise exposure levels above 85 dBA, the recommended limit value in Tanzania. Immediate action with the provision of hearing protection for the workers is needed, and the metal companies and the labor and health authorities in Tanzania should discuss the reorganization of the work to protect workers from noise levels.