The Concentrations Of Phthalate In Chinese Residential Buildings And Its Influencing Factors

Semi-volatile organic compounds(SVOCs)are one of the main indoor pollutant categories.Phthalates are ubiquitous in indoor environment.Six phthalates(dimethyl phthalate(DMP),diethyl phthalate(DEP),di(isobutyl)phthalate(DiBP),di(nbutyl)phthalate(DnBP),butyl benzyl phthalate(BBzP)and di(2-ethylhexyl)phthalate(DEHP))in house dust samples were measured in sixty residential apartments in Tianjin,Urumqi,Chongqing and Kunming in four seasons throughout a year.The measured DEHP dust-phase concentration is in the range:11.9–1319.9?g/g,there are a large range of dust-phase concentrations;and it showed obvious differences in different seasons,and the average dust-phase concentration(253.6?g/g)in winter can be about 2 times higher than the average dust-phase concentration(114.0?g/g)in summer in Tianjin.The DiBP and DnBP showed similar phenomenon.The corresponding gas-phase concentration is estimated considering the influencing factors of indoor temperature,air change rate,particle concentration which are monitored online.Then the dust-gas partition coefficient K_d under different season was obtained through the measured dust-phase concentration and estimated gas-phase concentration.From winter to summer,because the increased temperature leads to higher emission rate,the gas-phase concentration is obviously high in spite of the higher air change rate in summer.The estimated DEHP gas-phase concentration showed obvious differences in different seasons,and the maximum can be about 2times higher than minimum.The DiBP and DnBP showed similar phenomenon.The lower dust-phase concentration in summer is observed due to the temperature-dependency of the dust-gas partition coefficient.Therefore temperature has the greatest impact on the dust concentration,not influence via emission rate,but influence the partition coefficient K_d.In addition,there are few researches on the relationship between the phthalates content in settled dust and the“age”of house dust,which is the time that the dust is exposed in SVOCs-contained air.In this study,the relationship between the house dust“age”and its adsorbed SVOC amount was studied by field test in an occupied apartment and laboratory chamber experiment.We designed a static sealed chamber and selected three different composition dusts.However,compared with the adsorption process in the actual indoor environment,the dust absorption process in the test chamber is an accelerated process.So we used gauze to collect house dust to determine the concentration development of phthalate in common dwellings.The results of this study show the time dependence of SVOC adsorption into settled dust and provide support for further research.The time scale of indoor dust absorption reaching“saturation”is given for the first time.In addition,the frequency of indoor cleaning was analyzed through questionnaire survey,and the influence on the dust-phase concentration of SVOC in different locations of the room was also analyzed.It provides guidance for the effective control of indoor SVOC pollution level.