Evaluation of respirator filters for asbestos fibers.
Cheng-YS; Holmes-TD; Fan-B
J Occup Environ Hyg 2006 Jan; 3(1):26-35
Fiber aerosols are known to have different aerodynamic behaviors than spherical particles and usually carry higher electrostatic charges. We investigated the effects of flow rate and charge status of filter cartridges on the penetration of spherical and fiber aerosols. Four types of test respirator filters were selected: two for passive respirators, one for a powered respirator, and one disposable respirator. Surface charges on respirator filters were determined using a noncontact field electrostatic field meter. Penetration tests were performed for filter cartridges before and after charge neutralization. The surface charge measurements on the respirator filters showed that some filters, including those used in disposable face masks, are charged to enhance the collection efficiency. Only highefficiency particulate air filters performed consistently for both spherical test aerosols and the three types of asbestos fibers. The surface charge potential of filter cartridges and flow rate did not appear to affect the performance of these filters. In contrast to the high-efficiency filters, the aerosol penetration performance of low-efficiency filters and face masks deteriorated when the charge potential on the filter was removed. Our data also showed that the surface charges decreased in a hightemperature, high-humidity environment and disappeared after 1 week. Deposition of spherical particles and fibers in the charged disposable facemask filter was enhanced.For chargedneutralized, low-efficiency filter cartridges, asbestos fibers may penetrate more than spherical particles with a mean particle size of 0.3 um diameter.
Aerosols; Aerosol-particles; Fibrous-dusts; Inhalants; Sampling; Airborne-fibers; Air-sampling; Exposure-levels; Risk-factors; Asbestos-fibers; Asbestos-dust; Particulates; Analytical-processes; Chemical-reactions; Computer-models; Computer-software; Computers; Models; Face-masks;
Author Keywords: Asbestos; Disposal mask; Filter penetration; Respirator cartridge
Yung-Sung Cheng, Lovelace Respiratory Research Institute, 2425 Ridgecrest Drive SE, Albuquerque, NM 87108
Journal of Occupational and Environmental Hygiene
Lovelace Biomedical & Environmental Research, Albuquerque, New Mexico