Project Title: Aerosol Size Distribution Study of Cooking Fumes Emitted from Real Life Cooking Activities

Applicant: Hong Kong University of Science & Technology

Total Approved Grant: $148,766.85 (ECF&WWGF: 50/50)

Duration: 01/08/2005 to 31/01/2006

Project Status/Remarks: Completed

Scope:
To develop new instrumental methods for the evaluation of the aerodynamic diameter in cooking fumes; to study the size distribution of cooking fumes generated from typical real-life Chinese and Western style cooking processes which generate the densest cooking fumes; and to find and set up a cooking fumes in real-life cooking but also with similar size distribution. The new cooking fume generation method will be adopted in the STP for the evaluation of the performance of air pollution control equipment.

Summary of findings:
Submicrometer and ultrafine particles were found in cooking fume generated from both Chinese and Western style real-life cooking.  In comparing of the two types of real-life cooking, stir frying in Chinese-style cooking generated relatively higher levels of particles with higher median diameters (MD).  High temperature and water content together with fat/oil promoted high emissions of cooking fumes due to the low boiling point of water, which agitates the emission of oil particles.   High concentrations of cooking fumes caused the disappearance of small aerosols due to coagulation.  As stipulated in the original Standard Testing Procedure (STP) for the performance tests on the pollution control equipment, the generation of cooking fume was carried out by heating oil at 300oC.   This method for the generation of cooking fumes was criticized because the physical size of the aerosols generated was different from the real-life cooking.   Finally, heating a water and oil mixture in 1:1 ratio at 300oC could simulate real-life Chinese-style cooking emissions not only in terms of submicrometer particle counts (467,404 cm-3) but also with similar median diameters of 134 nm.  This new method for the cooking fume generation can potentially be adopted in the STP for the performance test of the air pollution control equipment.