Occupational Carbon Monoxide Exposure Among Motorcycle Mechanics in Katsina State

Motorcycle mechanics in Nigerian urban environments are routinely exposed to carbon monoxide (CO) from engine exhaust without adequate ventilation or monitoring, presenting serious occupational health risks. This study assessed occupational CO exposure levels and associated health effects among motorcycle mechanics in Katsina metropolis, North West Nigeria. A cross-sectional design was employed, recruiting 145 mechanics from motorcycle repair clusters in Katsina Central local government. Ambient CO concentrations were measured using a portable electrochemical sensor, and health effects were assessed through structured questionnaire administration and carboxyhemoglobin estimation from venous blood samples. Results revealed that CO levels in 77.9 percent of repair locations exceeded the occupational exposure limit of 35 ppm TWA. Mean carboxyhemoglobin saturation was 6.3 percent, exceeding the threshold of clinical concern. Symptoms consistent with CO poisoning, including headaches (72.4%), dizziness (54.5%), and cognitive slowing (38.6%), were reported at significantly higher rates than in an unexposed comparison group. Workshop ventilation was rated as poor in 88.3 percent of sites. CO monitoring devices were entirely absent across all sampled locations. The study calls for mandatory ventilation standards in motorcycle repair workshops, occupational CO monitoring programs, health education on CO toxicity risks, and engagement of Katsina State Environmental Sanitation Agency in regulatory enforcement. Keywords: carbon monoxide, motorcycle mechanics, carboxyhemoglobin, occupational toxicology, Katsina State.