Background: Smoke from biomass combustion leads to around 3.2 million premature deaths annually, with a proportion of these deaths attributable to exposure to cook smoke during economic activities. One such economic activity that uses biomass fuel is cassava grits (gari) processing. Gari is a staple food produced from grated and fermented cassava in countries such as Ghana. The cookstoves used in the gari processing industry emit biomass fumes that expose workers and their children to pollutants such as fine particles diameter less than 2.5 micrometres (PM2.5) and carbon monoxide (CO), but little is known about the exposure levels for workers and the resulting health effects in this setting. Aim: The aim of this research was to quantify the levels of exposure to PM2.5 and CO among the cassava grits processors performing cookstove activities in the gari industry (workers) in the Bono East region of Ghana, and to investigate associations between these exposures and respiratory health condition among the workers and a comparison group. Methods: A cross-sectional observational study was conducted among 97 workers and 97 comparisons using portable exposure monitoring devices to measure individual PM2.5 and CO levels for 48-hours and a hand-held spirometer to measure lung function parameters in the Kintampo South and Techiman North Districts in the Bono East region of Ghana. PM2.5 and CO exposure was characterised by minute-averages for each study participant with three activity-hours categories: gari-working hours, active home hours (including home cooking and burning activities) and non-active home hours. Pulmonary function tests (FEV , FVC, FEV /FVC and FEF11 25-75%) were performed at the end of the 48-hour period and self-reported respiratory symptoms were collected by standardized questionnaires. Associations between PM2.5 and CO exposure and lung function and subjective respiratory symptoms were examined by a multi-regression model with adjustment for covariates including home cooking behaviours and education. Results: Study participants were exposed to very high levels of PM2.5 and CO: median (IQR) hourly- average exposure levels over 48 hours for workers and community comparisons were 76.2 (52.3-118.5) and 33.7 (19.7-52.5) μg/m PM2.5 and 3.1 (2.1-5.9) and 1.6 (1.5-1.8) ppm for CO, respectively. PM2.5 and CO exposure levels were also generally higher for the workers compared to the community comparisons during active or non-active home-hours. The analysis of associations between personal exposure to PM2.5 or CO and lung function suggested little evidence of associations between IQR change in PM2.5 and CO exposure and change in lung function parameters. There was evidence suggesting PM2.5 and CO exposure may affect detrimentally some lung functions among the comparison group, but not for the worker group. There was a significant difference in FVC% between workers and comparisons, an IQR change in minute-mean PM2.533 exposure level resulted in 1.53% (-0.88%, 3.94%) in workers vs -3.88% (-9.12%, 1.36%) difference in comparisons and 0.69% (-1.08%, 2.46%) in workers and -5.04% (-9.36%, -0.73%) in comparisons for CO. Moreover, this study found an increased risk of Restrictive pattern of pulmonary function abnormality in the comparison group compared to the worker group due to CO exposure. This finding was different in the assessment of self-reported respiratory symptoms, with the comparison group generally healthier than the worker group. Conclusion: This study suggests that workers in Bono East Region of Ghana are exposed to PM2.5 and CO levels that are nearly twice as high as those experienced by comparisons in the same communities. The assessment of self-reported respiratory symptoms revealed generally better respiratory health in the comparison group compared to the worker group. However, there was little evidence of an association between PM2.5 or CO exposure and lung function despite higher exposures in the worker group. Further studies are needed to assess the direct effects of air pollution exposure due to gari processing in workers employed in this industry