VOC Emission From Humans And The Interactions Between Humans And The Environment

To effectively control the volatile organic compounds(VOC)pollution,reseachers should pay more attention to the VOC source characteristics.The air pollution caused by the building itself,such as the building materials,is regarded as the main source of indoor air pollution.Humans are tradionally treated as the users and passive recipients of the environment.However,there is evidence that in some high density environment,humans could be regarded as an important source of VOCs.There lacks systematic research in this field.This thesis put forward the concept of hVOC(human VOC).Some key factors of the hVOCs were studied qualitatively and quantitatively,in combination with theory and experiment.The relationship between human and environment was expanded.The main academic contributions are as follows:First,the experimental methods are the basis for further research.In order to better serve the target,this thesis used Tedlar bags as the storage container,Tenax-TA tubes as adsorption,and TD-GC-MS as the analytical method for breath emission analysis.A condenser was used to remove moisture from the exhaled air so that disturbance of the Tenax-TA sorption could be avoided.For the skin emission analysis,the method of measuring the emission from whole human body and the method of decoupling respiration and skin was designed by using the environmental chamber,which is the most extensive method in material emission studies.The experimental errors were analyzed in depth.Second,with the improved experimental method to sample the exhaled VOCs,Using the experimental method developed previously,breath samples of 117 healthy human subjects were collected and analyzed.Concentration levels of 60 VOCs with the highest detection rates(DRs)were analyzed,and statistical results of emission rates of these VOCs are provided in a table for reference.Furthermore,net concentrations and emission rates of these VOCs were statistically compared among different gender,different age groups,and smoking exposure groups.The results of univariate analysis showed that these three factors may significantly affect the net concentrations and emission rates of some(but not all)VOCs.The regression model showed that,for most VOCs,active/passive smoking and being male or of older age were most likely associated with higher emission levels.The effects of metabolic rate on breath emissions were also reckoned.Third,for the first time,under the controlled experimental conditions,quantitative analysis of whole human body emission of VOCs was carried out.The results could provide reference to the indoor source apportionment studies as well as ventilation design in the built environment,especially in high density environment.The study found that the skin and breath had something in common.There also existed qualitative and quantitative differences.Compared to breath,skin seemed to be a more important source of pollution.Fourth,the environment could influence the potential for humans to act as sinks for VOCs via the respiratory system.Evidence was gained that humans could serve as either sources of or sinks for VOCs.Even when humans became sinks,not all VOCs were 100% absorbed.An increase in the concentration of inhaled VOCs could cause humans to become sinks of VOCs rather than sources.The results have implications for assessment of environmental exposure to VOCs: by accurately calculating human exposure,attention should be given to those air contaminants for which humans act as a sink.The results have possible implications for exposure assessments by accurately calculating the actual human exposure,so that more attention can be given to those air contaminants for which humans act as a sink rather than a source.