November 13, 2008: Extremely small nanoscale particles are released by common kitchen appliances in abundant amounts, greatly outnumbering the previously detected, larger-size nanoparticles emitted by these appliances, according to new findings by researchers at the National Institute of Standards and Technology (NIST). So-called “ultrafine particles” (UFP), ranging in size from 2-10nm, are emitted by motor vehicles and a variety of indoor sources.

NIST researchers conducted a series of 150 experiments using gas and electric stoves and electric toaster ovens to determine their impacts on indoor levels of nano-sized particles. Previous studies have been limited to measuring particles with diameters greater than 10nm, but new technology used in these experiments allowed researchers to measure down to 2nm particles — approximately 10× the size of a large atom.

This previously unexplored range of 2-10nm contributed more than 90% of all the particles produced by the electric and gas stovetop burners/coils. The gas and electric ovens and the toaster oven produced most of their UFP in the 10-30nm range.

The results of this test should affect future studies of human exposure to particulates and associated health effects, particularly since personal exposure to these indoor UFP sources can often exceed exposure to the outdoor UFP. Researchers will continue to explore the production of UFP by indoor sources. Many common small appliances such as hair dryers, steam irons and electric power tools include heating elements or motors that may produce UFP.

The experiments were conducted in a three-bedroom test house at NIST that is equipped to measure ventilation rates, environmental conditions, and contaminant concentrations.

NIST researcher Cynthia Howard Reed and guest researcher Lance Wallace measure nanoparticles emitted by common household appliances. The new experiments can measure ‘ultrafine particles’ ranging in size from 2-10nm. (Credit: NIST)