Sources and patterns of polycyclic aromatic hydrocarbons pollution in kitchen air, China

Twelve polycyclic aromatic hydrocarbons, multi-ringed compounds known to be carcinogenic in air of six domestic kitchens and four commercial kitchens of China were measured in 1999–2000. The mean concentration of total PAHs in commercial kitchens was 17 μg/m3, consisting mainly of 3- and 4-ring PAHs, and 7.6 μg/m3 in domestic kitchens, where 2- and 3-ring PAHs were predominant, especially naphthalene. The BaP levels in domestic kitchens were 0.0061–0.024 μg/m3 and 0.15–0.44 μg/m3 in commercial kitchens. Conventional Chinese cooking methods were responsible for such heavy PAHs pollution. The comparative study for PAH levels in air during three different cooking practices: boiling, broiling and frying were conducted. It was found that boiling produced the least levels of PAHs. For fish, a low-fat food, frying it produced a larger amount of PAHs compared to broiling practice, except pyrene and anthracene. In commercial kitchens, PAHs came from two sources, cooking practice and oil-fumes, however the cooking practice had a more predominant contribution to PAHs in commercial kitchen air. In domestic kitchens, except for cooking practice and oil-fumes, there were other PAHs sources, such as smoking and other human activities in the domestic houses, where 3–4 ring PAHs mainly came from cooking practice. Naphthalene (NA, 2-ring PAHs) was the most predominant kind, mostly resulting from the evaporation of mothball containing a large quantity of NA, used to prevent clothes against moth. A fingerprint of oil-fumes was the abundance of 3-ring PAHs. Heating at the same temperature, the PAHs concentrations in different oil-fumes were lard > soybean oil > rape-seed oil. An increase in cooking temperature increased the levels of PAHs, especially acenaphthene.