Study On Health Risk Assessment And Uncertainty Analysis Of Volatile Organic Compounds From Oil Refinery Units In Pearl River Delta,China

Volatile Organic Compounds(VOCs)play important roles in atmospheric photochemical reaction process as they are the key precursors of ozone(O3)and secondary organic aerosols(SOA).Moreover,many VOCs are toxic and hazardous,causing serious harm to human health.VOCs emitted from petroleum refineries is one of the important human sources,with high emissions,high concentrations and high pollution.Therefore,it is of great significance to study the potential health risks of VOCs from petroleum refineries.However,up to now,researches on the health risk assessment and uncertainty analysis of non-organized VOCs in petroleum refinery are relatively rare,many related studies are still in the initial stage.In this study,an oil refinery in the Pearl River Delta(PRD)region of China was selected as the research object.A campaign was carried out to measure the concentration of VOCs from typical devices,for example,Atmospheric and Vacuum Distillation Unit(AVDU),Catalytic Cracking Unit(CCU),Methyl Tertiary Butyl Ether Unit(MTBE),Alkylation Unit(AU),Hydrogen Unit(HU),Aromatic Combination Unit(ACU),Continuous Reforming Unit(CRU),Acidic Water Combination Unit(AWCU),Delayed Coking Unit(DCU)and Sulfur Recovery Unit(SRU).Pre-concentration GC/MS and PFPH-GC/MS methods were combined to detect the VOCs samples.In addition,the non-carcinogenic and carcinogenic risk assessments of VOCs in these typical device areas were evaluated by health risk assessment model,which was revised by localized parameters,health risk assessment of VOCs in respiratory exposure pathways was performed for workers in typical plant areas,and the key substances and devices were selected.Furthermore,uncertainty analysis of the VOCs risk assessment in these typical device areas were conducted by Monte Carlo method.The main conclusions are as follows:(1)VOCs species were detected in the device areas mentioned above,including alkanes(29 speices),alkenes(12 species),aromatics(16 species),halogenated VOCs(24 speices)and OVOCs(27 speices).The mass concentration range of TVOC in these unit areas are 1468.2 ~ 6431.8 ?g/m3.Alkanes accounted for the highest proportion in these units,which exceeded 50%.OVOCs was the second highest species which contribution was higher than 20%.Furthermore,the carcinogenic halogenated hydrocarbons accounted for less than 5%.Considering the concentration,the oil refinery need put prior control on the alkanes emission.(2)The non-carcinogenic risk assessment of VOCs via respiratory exposure pathways in the 10 typical units of the oil refinery was conducted using the revised US EPA's health risk assessment model.Results showed that the non-carcinogenic risk indices of VOCs in each facility exceeded the non-carcinogenic risk of US EPA.The risk of non-carcinogenic VOCs in Continuous Reforming Unit(CRU)was the highest,which was up to.The non-carcinogenic effects of VOCs in these facilities mainly derived from 1,3-butadiene,1,1,1-trichloroethane,acrolein and acetaldehyde.(3)The results of the risk assessment of VOCs in 10 typical facilities showed that 1,3-butadiene,benzene,ethylbenzene,chlorotoluene,1,2-dichloropropane,1,1,2-trichloroethane,formaldehyde and acetaldehyde had a significant carcinogenic risk,exceeding the US EPA's carcinogenic risk acceptable level(1.0E-6)by 1 to 2 orders of magnitude.(4)The total carcinogenic risk of the 17 carcinogenic VOCs via respiratory exposure pathways in the oil refinery facilities was in the range of 1.0E-6 to 1.0E-5,exceeding the US EPA's cancer risk recommendation(1.0E-6).The cancer risks of 17 carcinogenic VOCs were also different,which was in the following order: Hydrogen Unit(1.45E-4)> Aromatic Combination Unit(1.16E-4)> Catalytic Cracking Unit(1.12E-4)> Atmospheric and Vacuum Distillation Unit(9.37E-5)> Delayed Coking Unit(7.78E-5)> Methyl Tertiary Butyl Ether Unit(7.55E-5)> Alkylation Unit(7.5E-5)> Sulfur Recovery Unit(7.26E-5)> Continuous Reforming Unit(6.29E-5)> Acidic Water Combination Unit(4.51E-5).Therefore,there existed a large risk of potential cancer for the VOCs emitted from the facilities,indicating that more control measures should be done by the relevant business and environmental management departments.(5)The uncertainty analysis of health risk assessment was conducted by the Monte Carlo method.The results showed that the lower limit of the carcinogenic risk(5% of the total)of benzene in the facilities were all higher than that of US EPA risk recommendations recommendated value(1.0E-6)except for that of the Acidic water Combination unit(AWCU).The lower limit values of the carcinogenic risk caused by 1,3-butadiene,formaldehyde and acetaldehyde were all higher than that of recommendated value(1.0E-6)by the US EPA,and the carcinogenic risk was more obvious.