Studies On The Size Distribution And Polycyclic Aromatic Hydrocarbon Contents Of Submicron Aerosols

Aerosols affect the human health. It is the size of the inhaled aerosols that has a correlation with the degree of effect on the health. Generally, smaller aerosol, which has much effect on human health, has larger deposition efficiency in the bronchial and alveolar regions. Environmental tobacco smoke, mosquito-coil smoke and candle smoke are considered to be the major indoor combustion pollution. In this study, Field evaluations of the size distribution, decay and the concentration of polycyclic aromatic hydrocarbons in submicron particles generated by indoor familiar combustion.Firstly, the size distribution of submicron aerosols generated by combustion of cigarette and mosquito-coil smoke were determined by a high resolution scanning mobility particle sizer, which could measure the particles in the size range of 14～723 nm. The size distributions were found to be similar due to similar combustion mechanisms. The number median diameters (NMD) of smoking cigarette, smoldering cigarette and burning mosquito-coil were 99 nm, 86 nm and 80 nm, respectively. The decay of ultrafine particles was fastest, and submicron particles were in the next place. The particles which size are larger than 100 nm decayed slowest. On the average, it took 1-2 h to return to the background concentration values because of burning a cigarette or burning mosquito-coil for 15 minutes.Secondly, the size distributions of candle smoke in steady burning mode,unsteady burning mode and smoldering mode were very different. In steady burning mode, large quantities of ultrafine particles can be monitored, and relatively only a few particles are larger than 100 nm. The particle size distribution of this mode is approximately bimodal, with NMD of about 28 nm. In unsteady mode, most of the particles were also in the ultrafine range, with one peak and a larger NMD of about 40 nm. In smoldering mode, most of the particles were in the 50-160 nm range, with one peak and NMD of about 146 nm.Finally, particles larger than 1μm were removed by impactor under a controlled flow rate, and submicron particles were collected by Teflon filter membrane. It was innovative to use impactor for aerosol sampling. After ultrasonic extraction, polycyclic aromatic hydrocarbons in submicron cigarette smoke and mosquito-coil smoke were detected. The concentration of phenanthrene and anthracene in submicron cigarette particles were 214.4 ng/cig and 48.4 ng/cig, respectively, and biphenyl was detected in submicron mosquito-coil particles.