The issue of fine particle (PM2.5) exposures and their potential health effects is a focus of the scientific research because of the recently promulgated National Ambient Air Quality Standard for PM2.5 . It is necessary to understand total particle exposure issues and to determine the relative importance of the origin of PM2.5 exposure in various micro-environments. Eleven standard vacuum cleaners were tested for the emission rate of fine particles by their individual motors and for their efficiency in collecting laboratory-generated fine particles. For the tested vacuum cleaners, fine particle motor emissions ranged from 9.6 x 104 to 3.34 x 108 particles/min, which were estimated to be 0.028 to 176 µg/min for mass emissions, respectively.

The vast majority of particles released were in the range of 0.3-0.5 µm in diameter. The lowest particle emission rate was obtained for a vacuum cleaner that had a high efficiency (HEPA) filter placed after the vacuum cleaner bag and motor within a sealed exhaust system. Results show >99% of the fine particles were captured by the two vacuum cleaners that used a HEPA filter. A series of tests conducted on two vacuum cleaners found that the motors also emitted ultra-fine particles above 0.01 µm in diameter at rates of greater than108 ultra-fine particles/CF of air. The model that had the best collection efficiency for fine particles also reduced the ultra-fine particle emissions by a factor of 1 x 103.

Depending on the characteristics of the vacuum cleaner, its maintenance record, and age, the contribution of fine particles emitted during vacuuming to near field human exposures may be significant. Data can be used to estimate the relative importance of vacuum cleaning and, ultimately, other motor emissions versus exposures derived from particles emitted or generated outdoors.

(Journal of the Air & Waste Management Association, 2/99)

HEPA (High Efficiency Particulate Air) filters are special air filters capable of filter efficiency at ninety-nine and ninety-seven one hundredths percent (99.97%) of test aerosol with an average particle size of three-tenths (0.3) microns.