Research On Measurement Of Source And Sink Characteristic Parameters And Exposure Assessment For Indoor SVOC

Semivolatile organic compounds?SVOC?are ubiquitous in indoor environments.Human exposure to indoor SVOC has been found to be associated with multiple adverse health effects,such as respiratory system diseases,reproductive system diseases,and even cancer.Accurate measurement of characteristic parameters of source and sink materials,as well as accurate assessment of human exposure are the basic for controlling of indoor SVOC pollutions.Up to now,most of available methods for measuring SVOC source and sink characteristic parameters are time-consuming and of variable accuracy,which are inconvenient to be applied in practice;existing assessment models for SVOC dermal exposure have made some improper assumptions,inaccurate results may be obtained if these models are employed to access dermal exposure,to identify the primary exposure pathway,or to estimate total exposure for indoor SVOC pollution.Consequently,some relevant studies have been carried out in this dissertation,with the following academic contributions and conclusions:Firstly,a novel method,named M-history method,was developed for rapidly,accurately and conveniently measuring the characteristic parameter of SVOC source materials?y₀,gas-phase SVOC concentration in equilibrium with the source material?.In order to eliminate the error introduced by the extra estimation of convective mass transfer coefficient,the chamber was sealed;to address the problem of sampling SVOC in a sealed chamber,Solid-phase micro-extraction?SPME?was employed;furthermore,utilization of SPME can significantly shorten the testing time and simplify the experimental operation processes.Experiments have demonstrated that the testing time of this method?less than 8hours?was much shorter than existing methods,which was reduced by more than20 times;the measured y₀ for the same source materials were consistent between the present method and another method reported in the literature,the relative deviation between them was less than 2%.Taking di?2-ethylhexyl?phthalate?DEHP?emitted from PVC flooring as an example,influences of temperature and SVOC content in materials on y₀ were studied,including explanation of mechanisms and derivation of quantitative formula.This method is convenient for abundant measurement of y₀ in practical application,and these conclusions provide deeper understanding on emission characteristics of SVOC source materials.Secondly,a model was established to describe SVOC mass transfer in existing chambers that has been used for measuring sink characteristic parameters,main reasons that make existing methods be time-consuming and inaccurate were analyzed.Following this analysis,two novel methods for measuring characteristic parameters of SVOC sinks were developed:C _m-history method for measuring partition coefficient and C_a-history method for measuring diffusion coefficient.The errors of measured parameters can be reduced by simultaneously placing SVOC source materials and the targeted sink materials in a chamber,the testing time can be shortened by measuring SVOC concentrations in a series of times?a transient method?and using a flat,thin,and sealed chamber.Additionally,approaches for selecting the appropriate testing time were discussed based on the principle of minimum error.These two methods provided potential technical means for abundant and accurate measurement of SVOC sink parameters.Finally,based on results obtained by 3D body scanner in leteratures,the exiting model for assessing SVOC dermal exposure was modified,which comprehensively considered factors that influence SVOC dermal exposure.In the modified model,two pathways:direct contact and air gap,were considered when describing SVOC transport between skin surface and clothes,while existing model only considered the pathway of air gap.Under the same experimental conditions,estimations of this model agreed well with measured results in the literature,reflecting the accuracy of the present model.Deeper analysis showed that direct contact was the primary pathway for SVOC transport between skin surface and clothes.The present model provides an available way for accurate ly assessing dermal exposure to SVOC.