Dust exposure levels among treet sweepers in Bole Sub-City, Addis Ababa, Ethiopia

Abstract

Background: Intensive manual street sweeping has been performed over the last three years in Addis Ababa to optimize the cleanliness of the surface of the street and make it convenient for public use. Street sweeping is a job, but it is a job that also has a direct link with the health of the sweepers. Street sweepers are severely exposed to street dust. Yet, the level of dust exposure among the sweepers has not been documented in Ethiopia.

Objective: The aim of this study was to assess the level of exposure of dust to street sweepers in Addis Ababa city.

Methods: An exposure study was conducted among 10 street sweepers, measuring exposure levels for four working days. The measurements were performed by total dust samplers (37 mm Millipore plastic cassette with a PVC filter) attached to the breathing zone of the workers. Gravimetric analysis of the filters was done using a Mettler Toledo XPE105 micro-balance (detection limit 0.01mg). The sampling cassettes with filter were conditioned in desiccators for 24 hours before weighing. A survey data sheet and an observational checklist were used to record exposure attributes. Data were analyzed using SPSS Version 20. The exposure levels were compared with the threshold limit value for total dust recommended by the American Conference of Governmental Industrial Hygienists of 10 mg/m³.

Results: The study participants covered a total of 1km, and were sweeping from 6:00-9:00 am. The participants were assumed to constitute one similar exposure group as all sweepers covered four operations in performing the street sweeping: sweeping the street surface, collecting dust and litter in one place, putting it in a container and then disposing it at a disposal site designated for this purpose. The median dust exposure level (n=19 samples) was 10.71 mg/m³ (IQR=7.43). This is above the threshold limit value of 10 mg/m³. Eleven of the samples exceeded the occupational exposure level. The exposure level did not vary significantly between sampling days. This indicates that the exposure variability is consistent across the four sampling days.

Conclusion: The studied street sweepers were exposed to dust levels that exceeded the recommended exposure level. Additional comprehensive research in a larger exposed population is suggested to further identify the most important determinants for high exposure levels among street sweepers. Studying characteristics of the street dust is another suggested area for future research. [Ethiop. J. Health Dev. 2017;31(4):236-243]

Keywords: Street sweeping, dust, exposure level, Addis Ababa, Ethiopia