Study On Characteristics Of Passenger Car In-door Air Pollutants

BTEX(benzene, toluene, ethylbenzene and xylene), styrene, formaldehyde, acetaldehyde and acrolein existing in the cabins of 35 new cars from various automakers were quantified by using thermal desorption- capillary gas chromatography/mass spectrometry and high-performance liquid chromatography. Health risk of these toxic materials at the measured concentrations was further evaluated with health risk assessment model developed by the USEPA. The relationship between the concentration of eight kinds of contaminants and temperature, and hermetic time were discussed through the same test method. Studied on the regulation of concentration of pollutants from vehicles exposed to the sun about four hours to enter the car, then start the engine and turn on air-conditioning at the same time.The results showed that, except for acetaldehyde, the other pollutants were all below their limit values recommended by GB/T 27630. The maximum concentrations of ethylbenzene, benzene, toluene and formaldehyde identified in this research were found only 33.3%, 67%, 72.5% and 72% of the limit values. Only small deviation of the measured xylene concentrations was noticed from sample to sample, the crew-averaged concentration of xylene was only about 12% of the limit value while the concentrations of styrene and acrolein were far below the regulatory caps. Both the measured concentrations of benzene and formaldehyde might have carcinogenic impacts on people exposed in such environment. Measured concentrations of toluene, ethylbenzene and styrene can not cause non-cancer harm to human health. Non-cancer risk of xylene at the measured concentrations indoor was 78% higher than the USEPA baseline. Therefore, it hazarded human health. At the same airtight time, the concentrations of the benzene, toluene, ethylbenzene, xylene, styrene, formaldehyde, acetaldehyde and acrolein increased with the temperature increasing inside the car. The section of temperature from 10℃ to 20℃ increased slowly, and the section of 30℃ to 40℃ increased quickly relatively. At the same, The concentrations of these eight kinds of pollutants increased with the extension of the hermetic time, and the increase in volume was not in direct proportion to the hermetic time of vehicles, but close to the logarithmic curve.Benzene, toluene, ethylbenzene, xylene, styrene, formaldehyde, acetaldehyde, acrolein and acetone, propionic aldehydes, acrolein and methyl valeraldehyde had been detected in three models of three cars. After 4 hours exposure of high temperature, the concentrations of total VOC and carbonyls increased 1-3 and 6-14 times higher than that of the normal standard mode. Then in after 30 mins of idle operation mode, the concentrations of those contaminants reduced at least 80%. Health risk of these toxic materials at the measured concentrations was further evaluated. The results showed that, in addition to high temperature mode, the cancer risk of benzene and formaldehyde, and the non-cancer risk of xylene and acetaldehyde in normal standard mode and idle operation mode were all below the USEPA baseline, which risk was acceptable, and its risk reduced at last 97% in the last idle operation mode.