Assessment of Air Quality and Respirable Dust Exposure in Cement Manufacturing Workers in Sokoto State

Occupational exposure to cement dust in manufacturing facilities poses documented respiratory health risks, and workers in Nigerian cement plants in the North West zone represent an under-studied population for such assessments. This study measures respirable dust concentrations and selected chemical constituents, including silicon dioxide, calcium oxide, and chromium, at seven work stations within a cement manufacturing plant in Sokoto State over a 12-week monitoring period. Personal and area sampling was conducted using pre-weighed polyvinyl chloride filter cassettes attached to constant-flow sampling pumps. Filter analyses for mass concentration and elemental composition were performed by gravimetric analysis and energy-dispersive X-ray fluorescence. Respirable dust concentrations at the raw mill, kiln feed, and packing stations exceeded the occupational exposure limit of 1 mg/m3 for crystalline silica by factors of 1.4 to 3.2. Workers in the packing area recorded the highest time-weighted average exposure levels. Dust control effectiveness was assessed at stations with operational local exhaust ventilation, revealing 48 to 62% concentration reductions compared to unventilated stations. Medical questionnaire results indicated a higher prevalence of chronic cough and dyspnoea among workers with more than five years of exposure. The study recommends urgent enhancement of dust control engineering measures and periodic health surveillance for cement workers in Sokoto State. Keywords: cement dust, occupational exposure, silica, air quality, Sokoto State