Impacts of Ambient Hydrogen Sulphide Exposure to Workers in Olkaria Geothermal Power Station, Kenya

Abstract

Geothermal exploration and power generation taps on the heat of the earth crust to meet mans energy demands. In the process, non condensable gases escape into the atmosphere. One of the most noticeable gases of public health concern is Hydrogen sulphide (H2S). This study sought to investigate the exposure to H2S concentration to workers in Olkaria geothermal power plants in Kenya. Olkaria geothermal power plants operated by KenGen at Hells gate national park in Nakuru County are the largest geothermal power plants in Africa. There is a general workplace belief that smell of rotten eggs in the power plants is mere nuisance; and no hazard if it exists below the total weighted average (TWA) for occupational exposure limits (OEL) of 10ppm. Using questionnaires administered to a sample of the operations and maintenance team, impacts of exposure to ambient H2S were investigated. Ambient measurements of H2S were taken at hourly intervals at purposely selected sampling points in the two power stations. Clinical records for staff working in the operations department indoor conditions were reviewed and compared with those who worked in other sections. In most occurrences (> 80%), the measurements of H2S ranged between 0.1-1.0ppm which is a weak smell above the odor detectable threshold. According to Costigan, 2003 exposure to H2S within 2.0 -7.0 ppm levels may cause nausea, tearing of the eyes, headaches, loss of sleep and airway problems. Respondent who work in operations and maintenance required a combination of physical, mental and visual - audio skills where (p >0.37, n=40) at 95% confidence levels. The study found out that presence of H2S smell at workplace contributed to quick exhaustion of employees which would affect performance. Notably, however this was not the only contribution to exhaustion hence T- test P value = 0.193, at p<0.05 were not significant to cause the rejection of null hypothesis. Again the probability that strong pungent smell of rotten eggs at workplace in Olkaria geothermal power stations does cause discomfort to employees at workplace is not significantly proven (df=39, P value = 0.112, at p<0.05). However it was shown that physical work environment satisfactorily impact on the employees causing fatigue (df=39, P value = 0.0001 is significant at p<0.05). When a smell is persistent at workplace for a long time, the results satisfactorily showed that a worker significantly gets accustomed to the condition (exhausted (df=39, P value = 0.0295 is significant at p<0.05). The study concluded that there were weak direct associations between exposure to low ambient H2S concentrations to workers in the Olkaria Geothermal power plant and the impacts on their health and comfort and subsequent performance. Analysis of clinical cases with similar diagnosis to exposure to H2S was 114.8% higher for the 12 hr operations and maintenance shift staff than the rest of the population working in the same department for 8hour shift. Since identification of an occupational disease by ILO is not necessarily a pure science, associations that are consistent with other researchers are considered. In Iceland, action to adjust the OEL was reached by monitoring the rising complaint cases related to exposure despite lack of existence of a study confirming the correlation.