Effect of Kitchen Range Hood on Exposure to Ultrafine Particles from Gas and Electric Stoves

DONGHYUN RIM (1), Lance Wallace (1), Andy Persily (1)

The National Institute of Standards and Technology

     Abstract Number: 397
     Last modified: November 9, 2009

Abstract
Gas and electric stoves are present in most homes and are perhaps the most common indoor source of ultrafine particles (UFP). UFPs have been observed to be associated with adverse respiratory and cardiovascular effects among susceptible individuals in the population. The objective of the present study is to investigate the effect of using a kitchen range hood on exposure to UFPs from gas and electric stoves.

The experimental measurements were conducted in a manufactured house (volume of 340 m^3). Using a Scanning Mobility Particle Sizer (SMPS; TSI, Inc. Shoreview, MN) consisting of an electrostatic classifier, nano-differential mobility analyzer (nano-DMA) and water-based condensation particle counter (WCPC), UFPs ranging from 2 nm to 64 nm in size were monitored in a bedroom and kitchen. The average measured flow rate through the lower-quality range hood was 65 cfm; a higher-quality range hood with higher flow rate will also be tested.,. The UFP size distributions produced by the gas flame alone (no pots) and boiling water were characterized with the hood fan on and off. Furthermore, the effect of gas burner position (front vs. back) on the efficiency of the range hood was examined.

The following results were with the gas stove and lower quality range hood. Results with the electric stove and higher quality range hood will also be reported. Peak concentrations ranged from 70,000 cm^(-3) to 26,000 cm^(-3) with hood off, and from 40,000 cm^(-3) to 18,000 cm^(-3) with hood on for particles from 2 nm to 30 nm with 90 % of particles below 20 nm. The range hood was only effective for the removal of UFP larger than 15 nm. With regard to UFP smaller than 10 nm (which constituted 60% to 90% of the total), very small or no change in particle number was observed with the kitchen hood operating. This may be explained by the strong particle or turbulent diffusion for UFP smaller than 10 nm, which causes the particles to transport out of the thermal plume from the flame. Regarding the impact of burner position, much larger particle reduction with the back burner was observed than with the front burner, which was likely due to the more efficient entrapment of the particles from the back burner. The tests with the gas flame alone produced more UFPs smaller than 10 nm compared to those with boiling water, implying that the presence of the boiling pot contributes to particle coagulation and produces larger particles. A scaling analysis between air flow rate and particle or turbulent diffusion force will be presented. Overall, the research will contribute to the fundamental understanding of the escape mechanism of particles from the particle-laden heat plume.