Electrostatic effects in asbestos sampling. I: Experimental measurements

Journal Article · Thu Feb 01 04:00:00 EST 1990 · American Industrial Hygiene Association Journal; (USA)

DOI:https://doi.org/10.1080/15298669091369330· OSTI ID:6947743

Baron, P A; Deye, G J ^[1]

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1. National Institute for Occupational Safety and Health, Cincinnati, OH (USA)

Electrostatic charge can cause errors during sampling of airborne asbestos fibers and other particles. The change in particle trajectories caused by charge effects during sampling can result in nonuniform deposits on the collecting filter surface and net loss of sample. The purpose of this research was to evaluate the dependence of sampling efficiency and sample uniformity on these variables. Humidity has been postulated as a primary determinant of particle charge during aerosol generation. Measurements of particle charge and concentration were made as a function of relative humidity with chrysotile fibers generated from a fluidized bed. A strong increase in charge and a decrease in concentration of fibers was noted as the relative humidity was decreased below 15%. The effects of conductive versus nonconductive samplers and sampling flow rate were measured as a function of particle and sampler charge levels. Nonconductive samplers can carry a large and variable charge distribution on their surfaces. This can result in a biased and highly variable particle deposit on the filter when sampling charged particles. Conductive cowls spread any acquired charge over the entire surface and produce a more symmetrical and less biased charged particle deposit. Increasing the sampling flow rate will improve sampling efficiency and decrease deposit variability because the charged particle has less time to interact with the field produced by the sampler. These results suggest that sampling problems caused by electrostatic charge interactions are most likely to occur under low humidity conditions of dust generation, that sampling should be done at as high a flow rate as possible to reduce these effects, and that analysts should select fields toward the center of the filter to minimize bias and variability. 36 references.

• OSTI ID: 6947743
• Journal Information: American Industrial Hygiene Association Journal; (USA), Journal Name: American Industrial Hygiene Association Journal; (USA) Vol. 51:2; ISSN AIHAA; ISSN 0002-8894
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AIR POLLUTION
AIR POLLUTION MONITORING
AIR SAMPLERS
ASBESTOS
DOCUMENT TYPES
ECOLOGICAL CONCENTRATION
ELECTRIC CHARGES
EQUIPMENT
HUMIDITY
POLLUTION
REVIEWS
SAMPLERS