| Cooking oil fume is one of the most direct and most common pollution sources in our daily life,which seriously affects the outdoor air environment and indoor air quality.The pollution of formaldehyde,VOCs and particulate matter produced by cooking oil fume after oil heating will directly affect human health.Therefore,it is important to clarify the concentration level and emission characteristics of formaldehyde and VOCs in cooking oil fume and analyze the influence of oil type,oil temperature,heating times and oil grade on them,which has important significance and practical reference value for improving people’s cooking behavior and cooking habits in daily life.In view of this,this paper selects 8 kinds of cooking oils,including 5 kinds of first grade vegetable oils(rapeseed oil,soybean oil,peanut oil,blend oil,sunflower oil),2kinds of third grade vegetable oils(soybean oil,rapeseed oil)and 1 kind of animal oil(lard).Firstly,the constant temperature electric plate is used as heating and temperature control device of edible oil in the 8m~3 environment cabin,the contents of benzene series(benzene,toluene and xylene)and TVOC in cooking oil fume at different oil temperatures of 190,220 and 260℃were collected and determined by GC-MS.Meanwhile,the concentrations of formaldehyde in cooking oil fume at different oil temperatures were measured,and then the concentrations of formaldehyde,benzene series and TVOC in cooking oil fume at three different temperatures were analyzed;Then,the emission rates and emission factors of benzene series,TVOC and formaldehyde were determined based on the indoor gaseous pollutant mass balance equation.Under the condition of natural ventilation,the exposure margin of formaldehyde and BTEX from cooking oil fume in actual kitchen was evaluated by using the exposure margin evaluation method;Finally,the concentration of benzene series,TVOC and formaldehyde in cooking oil fume was predicted by using equilibrium equation in a given volume kitchen at different oil temperature and air exchange times.The important role of ventilation on controlling cooking oil fume and reducing its influence on human health was also clarified.The main conclusions are as follows:(1)The average concentrations of benzene,toluene,xylene and TVOC in cooking oil fumes from 190℃to 260℃were 0.002～0.059 mg/m~3,0.090～0.540 mg/m~3,0.008～0.125mg/m~3 and 1.735～18.519 mg/m~3,respectively.The average concentrations of formaldehyde were 0.081～0.523 mg/m~3.(2)The concentrations of benzene series,TVOC and formaldehyde produced by cooking oil fumes all increase significantly with the increase of oil temperature,and at the same oil temperature,the third grade oil is greater than the first grade oil,the second heating and the third heating are greater than the first heating.(3)Under the same oil temperature,the concentrations of benzene series,TVOC and formaldehyde in cooking oil fumes of rapeseed oil and sunflower oil with relatively high unsaturated fatty acid content were higher than those of soybean oil and peanut oil with relatively low unsaturated fatty acid content;The content of unsaturated fatty acids in lard is much lower than that in vegetable oil,and the concentrations of benzene series,TVOC and formaldehyde in lard are basically lower than those in vegetable oil at the same oil temperature.(4)When the oil temperature was 190℃,220℃and 260℃,the average emission rates of benzene were 0.002 mg/min,0.003 mg/min and 0.013 mg/min;the average emission rates of toluene were 0.051 mg/min,0.103 mg/min and 0.171 mg/min;the average emission rates of xylene were 0.007 mg/min,0.011 mg/min and 0.034 mg/min;the average emission rates of TVOC were 1.797 mg/min The average emission rates of formaldehyde were 0.050 mg/min,0.115 mg/min and 0.199 mg/min,respectively.(5)The temperature of oil was from 190℃to 260℃,the average emission factors of benzene,toluene,xylene,TVOC and formaldehyde of various edible oils were 0.016～0.133mg/(min·kg oil),0.507～1.710 mg/(min·kg oil),0.073～0.339 mg/(min·kg oil),17.966～71.923mg/(min·kg oil)and 0.458～1.820 mg/(min·kg oil).(6)The carcinogenic risk of benzene,toluene,xylene and formaldehyde in cooking oil fumes increased with the increase of oil temperature and cooking time.In general,the carcinogenic risk of formaldehyde and toluene is relatively high.(7)Prediction of the concentration of pollutants in natural ventilated kitchens in this article showed that the peak concentrations of benzene,toluene and xylene in cooking oil fumes in the kitchen did not exceed the standard limits;the peak concentration of TVOC was 2.37～9.47times of the standard limits;the peak concentration of formaldehyde was 1.42 times of the standard limits when the oil temperature was high and the ventilation was poor.(8)It is recommended to use range hoods or exhaust fans for exhaust and ventilation during cooking.In particular,natural ventilation should be fully utilized.Good ventilation in the kitchen is necessary to reduce the concentration level of cooking oil fume-related pollutants and the risk of carcinogenesis.Health is of great significance. |
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