Smaller Than Previously Detected

Photo: Man and woman with measuring device in kitchen

Nanoparticles emitted by common
household appliances can harm
the health; © NIST

So-called "ultrafine particles" (UFP) range in size from two to ten nanometers. They are emitted by motor vehicles and a variety of indoor sources and have attracted attention because of increasing evidence that they can cause respiratory and cardiovascular illnesses.

The 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 ten nm, but new technology used in these experiments allowed researchers to measure down to two nm particles - approximately ten times the size of a large atom.

This previously unexplored range of two to ten nm contributed more than 90 percent of all the particles produced by the electric and gas stovetop burners respectively coils. The gas and electric ovens and the toaster oven produced most of their UFP in the ten nm to 30 nm 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. People often use these small appliances at close range for relatively long times, so exposure could be large even if the emissions are low.; Source: National Institute of Standards and Technology (NIST)