Aim The purpose of the study was to establish the association between exposure and respiratory health outcomes among charcoal workers.

Methods A cross sectional study was conducted among 307 workers from charcoal factories in Namibia. All respondents completed interviewer-administered questionnaires. Spirometry was performed on a subset of the sample and ambient and resipirable dust levels were assessed in different work sections.

Results Exposure to respirable dust levels across most of the job categories was above occupational exposure limits, with packing and weighing having the highest dust exposure levels (median 27.7 mg/m3, range: 0.2–33.0 for the 8 hour time weighted average). The prevalence of respiratory symptoms varied among males and females respectively: cough for more than 3 months (19.4% and 13%), breathlessness (21% and 35.5%), wheezing (29% and 26%) and phlegm (30.3% and 33%). Higher cumulative dust exposure was associated with chronic cough (OR: 2.11 95% CI: 1.11–4.00), phlegm for most days (OR: 2.13 95% CI: 1.10–4.10), and episodes of cough and phlegm (OR: 2.79 95% CI: 1.11–6.10). Ex-smokers had elevated odds ratios for several symptoms outcomes. Higher exposed workers had a lower mean predicted% FEV1 (98.1% (male) and 95.5% (female)) as compared to the low dust exposure category (101.1% (male) and 104.1% (female)).

Conclusions Charcoal dust levels exceeded the US OSHA recommended limit of 3.5 mg/m3 for carbon black containing material. Participants presented with exposure related adverse respiratory outcomes in a dose-response manner. Our findings suggest that stronger enforcement of regulations within the industry is required.