Objectives: To measure air pollutant concentrations in Chinese restaurant kitchens using different stove types and assess their influence on workers' respiratory health.
Methods: 393 kitchen workers from 53 Chinese restaurants were surveyed over 16 months: 115 workers from 21 restaurants using only electric stoves and 278 workers from 32 restaurants using only gas stoves. Workers were interviewed about their respiratory symptoms and had their lung function tested. Concentrations of nitric oxide (NO), nitrogen dioxide (NO(2)), carbon monoxide (CO), carbon dioxide (CO(2)), methane (CH(4)), non-methane hydrocarbons (NMHC), total volatile organic compounds (TVOC) and fine particulate matter (PM(2.5)) were measured using portable monitors and air-bag sampling. Temperature and noise levels were assessed.
Results: Median concentrations of NO, NO(2) and CO were 7.4, 1.5 and 1.6 times higher in gas-fuelled kitchens than in electric ones and average concentrations of PM(2.5) and TVOC were 81% and 78% higher, respectively. Differences were smaller for CH(4) and NMHC. Electricity-run kitchens were 4.5°C cooler and 9 dBA less noisy than gas-fuelled ones. Workers using electric cookers had significantly better lung function than their gas-using counterparts and their mean FEV(1) and FVC values were 5.4% and 3.8% higher, respectively, after adjustment for confounders. Wheeze, phlegm, cough and sore throat were more prevalent in workers using gas. The adjusted OR for having phlegm regularly was significantly higher.
Conclusions: The poorer lung function and higher prevalence of respiratory symptoms among workers in gas-fuelled kitchens compared to those in electricity-powered kitchens may be associated with exposure to higher concentrations of toxic air pollutants generated during gas cooking.