Effect of Biomass Smoke Pollutants on Respiratory Health of Food Vendors in Maiduguri, Northeast Nigeria

Background: Chronic exposure to biofuel smoke from biomass fuels like wood and charcoal poses major respiratory health risks, especially in low- and middle-income countries. Commercial food vendors in Maiduguri, Northeast Nigeria, often use these fuels for cooking, but their respiratory health effects are under-researched. Objective: This study examined the association between exposure to biofuel pollutants (PM2.5, CO, CO2, NO2, VOCs) and respiratory symptoms and lung function among commercial food vendors compared to controls without biomass smoke exposure. Methods: A cross-sectional comparative study enrolled 195 adult food vendors and 195 matched controls. Air pollutants were measured during peak cooking hours using portable sensors at vendor workplaces and control sites. Respiratory symptoms were assessed using the Modified Medical Research Council questionnaire; ventilatory function was measured by spirometry (PEF, FEV1, FVC, FEV1/FVC). Logistic regression and correlation analyses assessed pollutant effects. Results: Vendors were exposed to significantly higher median levels of PM2.5 (162 vs. 14 µg/m³), CO (36 vs. 2 ppm), CO2 (836 vs. 580 ppm), and VOCs (908 vs. 139 ppb) compared to controls (p < 0.001); NO2 levels were similar. PM2.5 exposure was significantly linked to increased odds of dyspnoea (OR=1.018; p=0.002). CO exposure correlated with cough (OR=1.043; p=0.051) and phlegm (OR=1.056; p=0.034). Lung function measures (PEF, FEV1, FVC) correlated positively with PM2.5 but negatively with CO2. Oxygen saturation did not differ between groups. Conclusions: Commercial food vendors in Maiduguri experience high biofuel pollutant exposure associated with increased respiratory symptoms and altered lung function, underscoring the urgent need for interventions to reduce occupational exposure.