Particle Size Distribution And Respiratory Exposure Of Two Typical Organic Pollutants In Environmental Tobacco Smoke

Heath issues on the smoking have been greatly raised in decades.Besides the direct exposure of smoking,the indirect exposures to toxic pollutants emitted from environmental tobacco smoke（ETS）and the third-hand smoke are significant in assessing the potential health risk of smoker and surrounding populations.As a result,we selected two cigarettes types（Virginian-type and Blended type）and 12?15volunteers smoked at an office at each sampling time.Wide–range Particle Spectrometer 1000 XP（WPS）was used to determine the particle number concentrations in the ETS.Atmospheric size-fractionated particle samples were collected using a 10-stage Micro-Orifice Uniform Deposit Impactor and analyzed for two kinds of classical pollutants,such as polycyclic aromatic hydrocarbons（PAHs）and tobacco–specific N–nitrosoamines（TSNAs）.The particle size distributions and emission factors of these two pollutants were examined and included in the estimating the related human inhalation exposure.In addition,clothes exposed to the EST were collected to examine the adsorption amounts of PAHs and TSNAs in clothes for evaluating the potential risk of the third-hand smoke.The main results were summarized as follows:The number concentrations of particles at 100 nm were the highest in the ETS from two type of cigarettes.The maximum number concentration of particles emitted from the Virginia-type cigarette has been reached at 30 min after smoking,whereas the maximum value for the Blended type cigarette was observed at 10 min and 50 min after smoking.The concentrations of gaseous PAHs in the ETS were dominated by the low molecular PAHs（2–3 rings PAHs）,whereas the concentrations of particle-bound PAHs were mainly contributed by the high weight molecular PAHs（4–5 rings PAHs）.The total concentrations and emission factors of PAHs from the Virginia-type cigarette were lower than those from the Blended type cigarette.For example,the average concentrations of gaseous PAHs from the Virginia and Blended types of cigarette were 170 and 370 ng m^-3,whereas the emission factors of particle-bound PAHs were 270±110 and 340±54.0 ng cig^-1,respectively.The particle size distributions of PAHs in the ETS from two cigarettes displayed at the peak in 0.1–1μm.Accumulation-mode particle at 0.56–1.0μm dominated in the deposition concentrations of PAHs in the human respiratory system.The gaseous and particle-bound concentrations of TSNAs from the Virginia-type cigarette were higher than those from the Blended type cigarette.For The Virginia-type cigarette,the concentration of individual TSNAs compounds followed the order of NNK>NAT>NNN>NAB;for the Blended type cigarette,the concentration followed the order of NNK>NNN>NAT>NAB.The emission factors of gaseous TSNAs from the Virginia and Blended types of cigarette were 1100±870 and 690±290 pg cig^-1,respectively,whereas those for particle-bound TSNAs were 240±33 and 190±75 ng cig^-1,The particle size distribution of TSNAs showed a single peak’s normal distribution with the peak at 0.1–1.0μm.The deposition concentrations of particle-bound TSNAs in the human respiratory system were size-dependent with the major contribution by particle at 0.56–1.0μm.In addition,the sorption capacity of PAHs and TSNAs were varied with different clothes.The greatest sorption amount of PAHs(2800±2600 ng g^-1)was observed at the clothes made from polyester fiber,whereas the greatest value of TSNAs(45±10ng g^-1)was found in the clothes made from nylon.Because the toxic pollutants adsorbed in the clothes could be emitted again,human exposure of to the contaminated clothes through dermal contact should not be ignored.