A Genetic Susceptibility Study of Lung Cancer Risk Potentially Associated with Polycyclic Aromatic Hydrocarbon Inhalation Exposure

For lifetime non-smokers, lung cancer risk is mainly associated with inhalation exposure to air pollution. For the Chinese population, indoor air pollution due to solid fuel combustion has been the primary source of inhalation exposure for decades. Polycyclic aromatic hydrocarbons （PAHs） are the by-products of incomplete combustion.

Emission factors of polycyclic aromatic hydrocarbons from domestic coal combustion in China

Domestic coal stove is widely used in China, especially for countryside during heating period of winter, and polycyclic aromatic hydrocarbons （PAHs） are important in flue gas of the stove. By using dilution tunnel system, samples of both gaseous and particulate phases from domestic coal combustion were collected and 18 PAH species were analyzed by GC-MS. The average emission factors of total 18 PAH species was 171.73 mg/kg, ranging from 140.75 to 229.11 mg/kg for bituminous coals, while was 93.98 mg/kg, ranging from 58.48 to 129.47 mg/kg for anthracite coals. PAHs in gaseous phases occupied 95% of the total of PAHs emission of coal combustion. In particulate phase, 3-ring and 4- ring PAHs were the main components, accounting for 80% of the total particulate PAHs. The total toxicity potency evaluated by benzo[a]pyrene-equivalent carcinogenic power, sum of 7 carcinogenic PAH components and 2,3,7,8-tetrachlorodibenzodioxin had a similar tendency. And as a result, the toxic potential of bituminous coal was higher than that of anthracite coal. Efficient emission control should be conducted to reduce PAH emissions in order to protect ecosystem and human health.

Characteristics of particulate-bound polycyclic aromatic hydrocarbons emitted from industrial grade biomass boilers

Polycyclic aromatic hydrocarbons（PAHs） are carcinogenic or mutagenic and are important toxic pollutants in the flue gas of boilers. Two industrial grade biomass boilers were selected to investigate the characteristics of particulate-bound PAHs： one biomass boiler retro-fitted from an oil boiler（BB1） and one specially designed（BB2） biomass boiler. One coal-fired boiler was also selected for comparison. By using a dilution tunnel system, particulate samples from boilers were collected and 10 PAH species were analyzed by gas chromatography–mass spectrometry（GC–MS）. The total emission factors（EFs） of PAHs ranged from 0.0064 to0.0380 mg/kg, with an average of 0.0225 mg/kg, for the biomass boiler emission samples. The total PAH EFs for the tested coal-fired boiler were 1.8 times lower than the average value of the biomass boilers. The PAH diagnostic ratios for wood pellets and straw pellets were similar.The ratio of indeno（1,2,3-cd）pyrene/[indeno（1,2,3-cd）pyrene ＋ benzo（g,h,i）perylene] for the two biomass boilers was lower than those of the reference data for other burning devices, which can probably be used as an indicator to distinguish the emission of biomass boilers from that of industrial coal-fired boilers and residential stoves. The toxic potential of the emission from wood pellet burning was higher than that from straw pellet burning, however both of them were much lower than residential stove exhausts.