The issue of fine particle (PM 2.5 ) exposures and their potential health effects is a focus of scientific research because of the recently promulgated National Ambient Air Quality Standard for PM 2.5 . Before final implementation, the health and exposure basis for the standard will be reviewed by the U.S. Environmental Protection Agency within the next five years. As part of this process, it is necessary to understand total particle exposure issues and to determine the relative importance of the origin of PM 2.5 exposure in various micro-environments. The results presented in this study examine emissions of fine particles from a previously uncharacterized indoor source: the residential vacuum cleaner. 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. An aerosol generator was used to introduce fine potassium chloride (KC1) IMPLICATIONS It has been hypothesized that approximately 12% of the population in the United States vacuum twice a day, and more than 60% of the population vacuum at least once a week. Hotel workers vacuum nearly every day. Therefore 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. These exposures must be evaluated for the types of vacuum cleaners, for frequency of use, for intensity of exposure, and for the types of particles (e.g., carbon and trace elements) emitted to determine the dose. The results must then be placed in the context of the concentrations and other types of particles generated in outdoor air. Subsequently, these 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.particles into the vacuum cleaner inlet for the collection efficiency tests. Measurements of the motor emissions, which include carbon, and the KCl aerosol were made using a continuous HIAC/Royco 5130A light-scattering particle detector. All tests were conducted in a metal chamber specifically designed to completely contain the vacuum cleaner and operate it in a stationary position. For the tested vacuum cleaners, fine particle motor emissions ranged from 9.6 × 10 4 to 3.34 × 10 8 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 the motor within a sealed exhaust system. This vacuum cleaner removed the KC1particles that escaped the vacuum cleaner bag and the particles emitted by the motor. Results obtained for the KC1 collection efficiency tests show >99% of the fine particles were captured by the two vacuum cleaners that us...

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Gas-line filters are in widespread use in critical semiconductor manufacturing equipment and process lines. In this study, we developed accurate test methods for evaluation of these filters for particulate cleanliness during both steady flow and mechanical shock. Each test method and apparatus is described, and choice of testing conditions are discussed. Filters from four major manufacturers were evaluated and the data are shown and compared.