The charge distribution of indoor aerosol particles.
NIOSH 2001 Aug; :1-17
The majority of aerosol particles in indoor occupational environments are 10-500 nm in diameter. Recent studies with human lung cast (Cohen et. aI., 1995) have shown that the charged particles deposit five times more efficiently than the zero-charge particles in the size range of 20 - 200 nm. The significant implications of this increase in deposition include: 1) the enhanced deposition that results from particle charge will be important in airway dosimetry in size range of 10 - 500 nm since the depositions by diffusion and electrostatic charge are of the same order of magnitude for particles in this size range; 2) the increase in deposition from charge will need to be incorporated into general models used for lung airway dosimetry. However, little is currently known about how the charge is distributed with particle size in indoor occupational environment. This research developed a system based on the principles of the Tandem Differential Mobility Analyzer to measure the charge distributions of particles of 10 - 500 nm. The system is capable of measuring the fractions of zero-, singly, and doubly charged particles. The system is evaluated with Kr-85 neutralized NaCI particles. Common indoor aerosol particles are studied for their charge status under controlled conditions. The aerosols measured in this study are particles of indoor air in lab, cigarette smoke particles, particles from a vacuum cleaner. It is found that freshly generated (10 minutes after generation) cigarette smoke particles show an increased level of charge comparing Kr-85 neutralized NaCI particles. The particles in lab indoor air and from a vacuum cleaner (10 minutes after generation) show no increased level of charge comparing Kr-85 neutralized NaCI particles. Attempts are also made to measure the charge status of particles from kerosene space heater and cooking smoke. However, reproducible results were not achieved due to the difficulties in maintaining stable particle sources.
Aerosol-particles; Aerosols; Electrical-charge; Measurement-equipment; Air-quality-measurement; Airborne-particles; Electrical-properties; Laboratories; Lung-function; Dosimetry; Cigarette-smoking; Vacuum-cleaning-systems; Sodium-compounds; Kinetics
New York University, Medical Center, Institute of Environmental Medicine, 57 Old Forge Road, Tuxedo, NY 10987
Final Grant Report
Research Tools and Approaches; Exposure Assessment Methods
National Institute for Occupational Safety and Health
New York University, Medical Center, Institute of Environmental Medicine, Tuxedo, New York