ObjectivesThis study was conducted to assess the concentration of air pollutants at charcoal sites, the dose-response relationship between site-based exposure levels to air pollutants and prevalence of respiratory symptoms among charcoal workers, and the measures these workers employ to safeguard their health.DesignCross-sectional but comparative designSettingCharcoal production kiln sites in Sapele, Delta State, Nigeria.ParticipantsOverall 296 charcoal workers and age-matched, sex-matched and height-matched non-exposed traders (comparison group).Primary and secondary outcome measuresThe primary outcome measure was the prevalence of respiratory symptoms among charcoal workers while secondary outcomes included lung function indices as well as hazard control practices among charcoal workers.ResultsMajority (83.3%) of the sites had PM10and PM2.5values five times higher than the WHO standard. Charcoal workers were more likely to have respiratory symptoms; wheeze was statistically significant after adjusting for confounders, (OR 4.22; CI 1.37 to 12.99). The dose-response relationship between site-based exposure levels to air pollutants and the prevalence of respiratory symptoms among charcoal workers was statistically significant for all symptoms except chest tightness (p=0.167). Mean forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) were considerably lower among workers with differences of −0.22 (−0.42 to −0.05) L and −0.52 (-0.76 to −0.29) L, respectively, whereas FEV1/FVC ratio and peak expiratory flow rate were higher among workers with mean differences of 5.68 (3.59–8.82)% and 0.31 (-23.70 to 24.43) L/min, respectively; but the mean difference was significant only for the FEV1/FVC ratio. Charcoal workers had poor hazard control practices; only 3.4% reportedly used personal protective equipment.ConclusionAir pollutants at kiln sites were higher than WHO standards. Despite the significantly higher prevalence of wheeze, chest tightness and chronic cough among charcoal workers, their hazard control practices were inadequate. Charcoal workers should adopt appropriate hazard control practices, and use improved devices which emit minimal pollutants.
Intermediate Effect Biomarkers--Alternatives to Direct Concentration- Response Data for Regulatory Benefits Analyses
