Publication:

Occupational exposure levels to sewer gases among informal sewer workers in Nairobi city county, Kenya

Background The aim of this study was to evaluate occupational exposure levels to sewer gases among informal sewer sanitation workers in Nairobi City County, Kenya.

Methods An analytical cross-sectional study design was employed from October, 2023 to August, 2024 adopting quantitative and qualitative data collection methods. Nairobi City County was purposively sampled due to its high proportion of informal sewer sanitation workers. Interviewer-administered questionnaires to workers and semi structured key informant interviews were used to collect qualitative and quantitative data with an observation of exposure levels using EAGLE 2 multi-gas monitor equipment.

Results Results from the study revealed a 116 (44.7%) cumulative exposure levels to sewer gases among the workers, with exposures to H2S at 91 (35.1%), CO2 at 106 (40.9%) respectively. A mean higher exposure was observed for CO2 and NH3. Majority 221 (85.3%) of the respondents were manual pit emptiers. Moderate level of knowledge was reported among respondents. A high proportion 212 (81.9%) of workers were not in the right PPEs and had not received any training. A negative correlation not statistically significant (p=0.349) was established in examining relationship between the gases. In ANOVA, there was a statistically significant difference in exposure levels among the four groups of sewer workers, F (3,255) =7.803, p<0.001).

Conclusions The study concludes that 116 (44.7%) of informal sewer sanitation workers in Nairobi City County were exposed to cumulative elevated sewer gas levels beyond the TWA threshold. It is recommended that assessing the health impacts of both short-term and long-term exposure to sewer workers within informal sewer-operations.