Concentration Level And Risk Assessment Of Major Indoor Air Pollutants In Public Buildings

Concentrations of air pollutants levels has been one of the important standards of evaluation of indoor air quality.The importance of air quality in residential buildings was well known,but indoor air pollution in public places has only recently attracted people's attention.Although some scholars have carried out investigations and studied on indoor air pollution in public places,most of them focused on formaldehyde and benzene series pollution in entertainment places.There is a lack of comprehensive and systematic research on Formaldehyde,benzene series,TVOC,PM_2.5 and CO₂ in various functional public places such as shopping mall,gymnasiums,electronics city,furniture market and office.In view of this,this paper conducted on-site tested of formaldehyde,PM_2.5,CO₂,temperature and humidity,air flow rate,and on-site sampling of benzene series and TVOC to deeply explore the current indoor air pollution level in 5 types of public places including shopping malls,gymnasiums,electronics city,furniture market and offices.Through the analysis of the measured data,the concentration level,pollution status and influencing factors of various air pollutants in public places were obtained.Then,based on the pollutant concentration obtained from the research and the health risk assessment model,used the Monte Carlo simulation in the Crystal Ball software to evaluate the health exposure risk of workers in public places.Meanwhile,the uncertainty of exposure parameters was discussed by using sensitivity analysis in Crystal Ball software.The main conclusions are as follows.?1?The formaldehyde concentration in the 5 types of public places ranged from 0.018 to0.294 mg/m³,and the phenomenon of formaldehyde exceeded the standard was widespread.54%of the functional areas tested exceeded the standard,among which 37%exceeded the standard in the shopping malls and 44%exceeded the standard in the gymnasiums.The formaldehyde exceeded the standard in the functional areas in the electronic city,furniture market and office.The concentration of toluene in all test functional areas only reached 0.208 mg/m³ in the public catering area,which exceeded 4.2%,the exceeded functional area accounted for 2.7%,and the concentration of toluene and xylene was much higher than that of benzene.The concentration range of TVOC and PM_2.5 was 0.033⁰.526 mg/m³ and 0.002⁰.058 mg/m³,and there were no functional areas with excessive TVOC and PM_2.5.The CO₂ concentration of the test ranged from 619 to 1698 ppm,and the phenomenon of CO₂ exceeded the standard was prevalent.46%of the functional areas tested exceeded the standard,among which 47%,11%,100%,67%and50%of the functional areas in the shopping malls,gymnasiums,electronics city,furniture market and offices were exceeded.?2?The temperature in public places was generally on the high side,and the test range was20.3³3.1?.57%of all test functional areas had the phenomenon that the temperature was higher than the standard.Among them,63%,22%,100%and 100%of the functional areas in the shopping malls,gymnasiums,electronics city and furniture market had temperatures higher than the standard,but the temperature in the offices were within the standard range.The humidity test range in all test functional areas was 16.5%⁴7.7%,86%of which were below the standard,74%of which were in the shopping malls,and 100%of the other 4 places were below the standard range.The air flow velocity in all functional areas tested in the site ranged from 0.01 m to 0.53 m/s.Only 8%of the air flow velocity was higher than the standard,including 11%in the shopping malls and 33%in the furniture market.?3?The comprehensive index evaluation was carried out for 11 tested sites,among which the proportion of uncontaminated sites?81.8%?was the largest,and the number of clean sites and lightly polluted sites?9.1%?was the same.Five kinds of public places were evaluated by comprehensive index.The unpolluted places?80%?accounted for the largest proportion,and the remaining?20%?were lightly polluted places.?4?Through the analysis of the results of comprehensive index evaluation,indoor air quality in 37 test function areas was mainly affected by formaldehyde pollution in 35%,mainly affected by CO₂ in 49%,and affected by both CO₂ and formaldehyde in another 16%.In the 11test sites,55%of indoor air quality was mainly affected by formaldehyde pollution,27%by CO₂ pollution,and 18%by both CO₂ and formaldehyde.?5?Calculation of formaldehyde's respiratory exposure to CR among staffs in 5 types of staff,there were 40%public places where the CR value of formaldehyde was greater than 10^-4.The remaining 60%places'formaldehyde CR of staffs'who aged 18 to 44 was within 10^-6 to10^-4,and the formaldehyde CR of staffs'who aged 45 to 60 was greater than 10^-4.There were20%for benzene's CR in public places was less than 10^-6,which was less likely to cause cancer,and CR of benzene within 10^-6 to 10^-4 accounted for 60%,with the possibility of the cancer.As for another 20%of the areas,benzene's CR value of the staffs aged 18 to 44 was less than 10^-6,benzene's CR value of the staffs aged 45 to 60 was within 10^-6 to 10^-4.?6?The results of respiratory exposure to Cancer Risk were analyzed.Age and gender were taken as single variables respectively.The CR value of the formaldehyde or benzene in the same site was higher for workers aged 45-60 years or male workers.?7?Calculated the respiratory exposure to HQ of workers in 5 types of public places,75%of public places have the HQ of formaldehyde,and the highest HQ of formaldehyde is in the electronic city.The median HQ risk of benzene in all kinds of public places is far less than 1,which is not expected to cause significant harm to human health.?8?The results of respiratory exposure to Hazard Quotient were analyzed.Age and gender were taken as single variables respectively,and the HQ value of the formaldehyde or benzene in the same site was greater for workers aged 18-44 years or male workers.?9?The research results can provide basic data for the improvement of indoor air pollution control measures in public places and have important significance for the protection of human health in public buildings.