A study of exposure to ultrafine particles generated from cooking with a domestic kitchen range hood

使用家用抽油煙機的室內環境中超微細顆粒的暴露特徵研究

Student thesis: Doctoral Thesis

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Author(s)

  • Ka Man POON

Detail(s)

Awarding Institution
Supervisors/Advisors
Award date14 Feb 2014

Abstract

Ultrafine particles (UFPs) have been shown to be more harmful to human when compared with larger particles as they can penetrate deeper in the lungs. Cooking is one of the main sources of indoor air pollutants where the majority of its emission is UFPs. Therefore, understanding of the characteristics of cooking emission and developing control measures are very important for human health. This study focuses on the dispersion of the cooking pollutants, the effectiveness of a domestic kitchen range hood to exposure reduction, and various factors affecting exposures to cooking pollutants. All experiments were conducted in an environmental controlled chamber. The chamber contains two zones to mimic a kitchen and a non-kitchen zone (e.g. living room of a residential apartment). Single zone represents only kitchen zone involved; two-zone represents both kitchen and non-kitchen zones involved. Water and oil were heated to demonstrate realistic cooking. A domestic kitchen range hood was installed and operated to test its efficiency. To investigate the dispersion of cooking pollutants, the spatial distribution in the chamber was evaluated by measuring a total of six locations in both single zone and two-zone scenarios using a condensation particle counter (CPC) under various hood operational conditions. The size-resolved concentration was also measured by a scanning mobility particle sizer (SMPS) in two zones. The dispersion was found to be significantly affected by the hood operation. Change in air flow by the hood operation was the main reason. The particles with size about 20 nm transported more effectively from the kitchen zone to non-kitchen zone for both water and oil heating. Coagulation was found to take place which would influence on the size-resolved transport ratio under different hood operational conditions. Larger particles were formed by coagulation and the transport ratio could increase in the larger particle size range. Apart from the particle dispersion, the capture efficiency of the kitchen range hood was also investigated by measuring the size-resolved concentrations upstream and downstream of the exhaustion fan of the kitchen range hood. The results showed that approximately more than 90 % of particles of any size could be extracted for both water boiling and oil heating. However, the three hood power levels (exhaust flow rates ranged from 484 to 774 m3/h) did not show any obvious difference in capture efficiencies. It revealed that the kitchen hood could extract well at a close location. Furthermore, a numerical model was developed to predict the dispersion of the particles generated by cooking. Under the scenario without hood operation, the numerical results mostly agreed with the experimental results with some discrepancies. On the other hand, various factors of the exposure to cooking pollutants, such as types of cooking media and fuel, were investigated by utilizing a breathing thermal manikin (BTM). The results showed that exposure was greatly affected by all tested parameters, where the cooking media was a dominant factor. The presence of the BTM was found to reduce exposure in a less extent compared with the unoccupied measurement. The study revealed that exposure to cooking emission is greatly affected by both external environmental and inherent cooking parameters. Zone-to-zone dispersion was found to be significant if no hood was operated. The hood operation is important to reduce the exposure and control the particle dispersion.

    Research areas

  • Environmental aspects, Measurement, Indoor air pollution, Ventilation, Particles, Kitchens