Investigation Of Winter Indoor Microclimate And Air Pollution Condition In Hot Pot Restaurants Of Jilin

Hot pot is a unique and historical food in China and is popular with people.Hot pot restaurant is a special type of catering space,which means people can eat and cook at the same time,leading a variety of pollutants released into the room.In winter,the doors and windows of hot pot restaurants are always closed to keep the room warm,thus the indoor air pollutants reach a quiet high concentration and endanger people’s health.The air pollution of hot pot restaurants has become the key problem urgently to be solved in our society.Objective:To know the condition of microclimate and air pollution as well as factors that affect the indoor air pollution level by investigation of microclimate and air quality in different types of hot pot restaurants before and at the peak of business hours,providing baseline data for policy formulation and scientific basis for health monitoring in public places.Methods:In this study,we selected 48 hot pot restaurants in four areas of Jilin as the research object,the basic situation and air quality were investigated and analyzed.Survey content including temperature,relative humidity,CO,CO₂,NO₂,formaldehyde,PM₁₀ and the total number of bacteria,etc.The test results were evaluated according to the current public place health standard（GB16153-1996）.Using Excel2010 for database entry and SPSS16.0 for data processing and analyzing.Minimum,maximum,mean,standard deviation,median and quartiles were used to descript the measurement data.Count data expressed as a rate.Measurement data between groups and within groups were analyzed using ANOVA and paired t test,chi-square test with count data.Multiple factor linear regression was used at the level of α=0.05.Results:1.The survey included a total of 48 hot pot restaurant.The average temperature of hot pot restaurants is significantly lower than the peak hours.The average humidity of hot pot restaurants is significantly lower than the peak hours.Compared with the before-operating time,the average qualified percentage of temperature and humidity is significantly increased at the peak hours,but not the microclimate and air pollutions.2.Single factor analysis showed that the temperature of the hot pot restaurants before business is associated with the size and ventilation frequency（P<0.05）.Multiple linear regression analysis showed that the temperature of large-size hot pot restaurants was significantly lower than that of the small-size hot pot restaurants（P<0.05）.3.Before operating,the humidity of the hot pot restaurants is associated with the hygiene grade and fuels.Multiple linear regression analysis showed that the humidity of hot pot restaurants using electricity was significantly higher than that using charcoal（P<0.05）.As for the peak hours,single factor analysis showed that the humidity of the hot pot restaurants is associated with size and ventilation frequency.Multiple linear regression analysis showed that the humidity of hot pot restaurants using electricity and clean fuel was higher than that using charcoal（P<0.05）,and the humidity of hot pot restaurants ventilating at the peak hours was higher than that ventilating all time（P<0.05）.4.Before operating,the CO level is associated with fuels and ventilation facilities.Multiple linear regression analysis showed that the CO level of hot pot restaurants using electricity was significantly lower than that using charcoal（P<0.05）.As for the peak hours,single factor analysis showed that the CO level is associated with the hygiene grade and fuels.Multiple linear regression analysis showed that the CO level of hot pot restaurants using clean fuels and electricity was lower than that using charcoal（P<0.05）.5.The CO₂ level of the hot pot restaurants is associated with fuels and ventilation facilities both before and at the peak hours.Multiple linear regression analysis showed that before operating,the CO₂ level of hot pot restaurants using clean fuels was significantly higher than that using charcoal（P<0.05）,and the CO₂ level of hot pot restaurants using central air-conditioning was significantly lower than that using vent fans（P<0.05）.At the peak hours,the CO₂ level of hot pot restaurants using electricity was significantly lower than that using charcoal（P<0.05）.6.Before operating,the PM₁₀ level was associated with anti-smoking and ventilation frequency.Multiple linear regression analysis showed that the PM₁₀ level of anti-smoking hot pot restaurants was significantly lower than that didn’t ban smoking（P<0.05）,and the PM₁₀ level of hot pot restaurants ventilating all time was significantly higher than that ventilating at the peal hours（P<0.05）.At the peak hours,single factor analysis showed that the PM₁₀ level was associated with fuels and ventilation frequency.Multiple linear regression analysis showed that the PM₁₀ level of hot pot restaurants using electricity was significantly lower than that using charcoal（P<0.05）.7.Before operating,the NO₂ level was associated with size,fuels and ventilation facilities.Multiple linear regression analysis showed that the NO₂ level of medium-sized hot pot restaurants was significantly lower than the small-sized hot pot restaurants and the NO₂ level of hot pot restaurants using clean fuels was significantly higher than that using charcoal（P<0.05）,but compared hot pot restaurants using charcoal,the NO₂ level of hot pot restaurants using electricity was significantly lower（P<0.05）.As for the peak hours,single factor analysis showed that the NO₂ level was associated with fuels and ventilation facilities.Multiple linear regression analysis showed that the NO₂ level of hot pot restaurants using electricity was significantly lower than that using charcoal（P<0.05）.8.There was a significant difference in the total number of bacteria between hot pot restaurants using different ventilation equipment（P<0.05）.Conclusions:1.Compared with before-operating,the temperature,humidity and air pollutant concentrations were significantly increased in hot pot restaurants at the peak hours;the qualified rates of temperature and humidity were significantly increased and the qualified rates of CO,CO₂,formaldehyde and NO₂ were significantly reduced.2.Fuel types are the influence factors of humidity,CO,CO₂,PM₁₀ and NO₂ levels in hot pot shop.The before-operating CO level and the CO₂,PM₁₀ and NO₂ levels at the peak hours of hot pot restaurants using electricity were significantly lower than that using charcoal.The humidity of hot pot restaurants using electricity was significantly higher than that using charcoal both before operating and at peak hours.The before-operating CO level of hot pot restaurants using clean fuel was significantly lower than that using charcoal.The before-operating CO₂ and NO₂ levels as well as the humidity at peak hours were significantly higher than that using charcoal.3.Before-operating temperature of large-sized hot pot restaurants was significantly lower than small-size hot pot restaurants.Before-operating NO₂ level of middle-sized hot pot restaurants was significantly lower than small-size hot pot restaurants.4.Compared with the hot pot restaurants ventilating all time,the humidity at peak hours of hot pot restaurants ventilating at peak hours was significantly higher but the before-operating PM₁₀ level of hot pot restaurants ventilating at peak hours were significantly lower.5.The before-operating CO₂ level and total number of bacteria at peak hours of hot pot restaurants using central-air conditioning were significantly lower than that using vent fans.6.We advise that hot pot restaurants should altered the type of fuels and stoves,increase ventilation equipment,extend the ventilation time,streamline the decoration,and ban smoking during the business period.