Exposure and cancer risk toward cooking-generated ultrafine and coarse particles in Hong Kong homes

Particulate matters generated during cooking contain various carcinogens. These particles consist of both ultrafine particles (nanoparticle) and coarse particles. Exposure and risk-assessment studies often use particle mass concentration as dosimetry, which ignores the impact of ultrafine particles due to their insignificant mass compared to coarse particles. This study aims at characterizing the cancer risk toward cooking-generated particulate matter using Hong Kong homes as an example. A risk-assessment scheme modified from an existing risk model was developed to consider the cancer risk contributed from both fine ultrafine and coarse particles. Exposure assessment was conducted based on particle concentration data measured in 16 Hong Kong homes. The predicted cancer risk was then compared to the cancer incidence rate in Hong Kong to examine its appropriateness. It was found that the ultrafine particles contribute a much higher risk than that of coarse particles, and the modified risk-assessment scheme gives an estimate much closer to the incidence rate than the conventional scheme. Use of grease extractor cannot completely contain the particles, and a significant portion of particles can be transported from kitchens to other regions of the homes. The modified risk assessment scheme can serve as a tool in assessing environmental quality as well as setting up design and ventilation guidelines and exposure standards on particulate matters.