Workplace Aerosol Sampling at Realistic Low Windspeeds

Details

• Personal Author:
  Sleeth DK ; Vincent JH ; Wu Y-H
• Description:
  This Report describes a large body of research that involved the development of facilities never previously seen and their application in the exploration of human inhalability in relation to aerosol exposures under realistic windspeed conditions. The specific objective was to acquire experimental data on the efficiency with which humans inhale particles in the range of particle aerodynamic diameter up to about 90 um and on a range of personal sampling instruments aimed at making representative measurements of the inhalable fraction. The new facility consisted of a novel ultra-lowspeed wind tunnel capable of providing windspeeds in the range from about 0.05 to 0.5 m/s representing realistic conditions in most actual workplaces, and a mannequin capable of simulating breathing parameters and body temperature representative of people at work. The experimental research program began with flow visualizations to examine the nature of the patterns of air movement around the heated, breathing, followed by studies of human inhalability and personal sampler performance. The flow visualizations provided striking visual information about the roles of windspeed and breathing flowrate, as well as body heat, clothing, etc., on the nature of the flow, in tum enabling to qualitative assessment of the potential influences on aerosol transport and hence human aspiration efficiency. At combinations of low windspeed and high breathing rate, and especially for breathing through the mouth, it was seen that large and persistent disturbances in the approaching air flow were generated. It was postulated that such disturbances will have a significant influence on aerosol transport near the mannequin, and so on inhalability and personal sampler performance. This was borne out in the sets of data that were obtained for both aerosol inhalability and personal sampler performance. These showed that both human inhalability and personal sampler performance were significantly dependent on windspeed, both being the highest at the lowest windspeed. In particular they revealed that inhalability at ultra-low windspeeds was much greater than the currently-accepted criterion based on data obtained at higher windspeeds. This was shown to be true also for the personal samplers tested, namely the IOM, Button and GSP inhalable aerosol samplers and the closed-face cassette sampler (CFC) widely used by industrial hygienist in the United States. While the IOM, Button and GSP samplers were shown to provided adequate measures of what was inhaled by the mannequin, the CFC sampler did not. We next examined the possibility (and implications) of modifying existing inhalability criteria to better estimate workplace exposures at the ultra-low windspeeds of interest. It was concluded that the existing criterion (e.g., as recommended by ACGIH and other standards-setting bodies) is still relevant to workplace environments where windspeeds exceed about 0.25 m/s. However a modified criterion is needed for lower windspeeds in the ultra-low range of the order of 0.10 m/s and below. A criterion for (nominally) calm air has already been recommended by researchers in Europe, and this is currently on the table for discussion by several major standards setting bodies. Our results are broadly consistent with that suggested new criterion, and so we support its inclusion in revised standards. Overall, the large body of research carried out under this project has provided important new findings relevant to occupational aerosol exposure assessment, and should therefore be of interest to industrial hygienists, occupational epidemiologists and standards setting bodies. At its core, the work has focused on issues underlying the fundamental principles of aerosol science and industrial hygiene. It is fair to say that the new wind tunnel and mannequin system have enabled the generation of data that will be highly significant in how we think in the future about inhalable aerosol in workplaces, providing a basis for improved standards and exposure assessment methodology. [Description provided by NIOSH]
• Subjects:
  Aerosols Air Movements Occupational Exposure Occupational Health Respiratory System Safety
• Keywords:
  Aerosol Particles Aerosol Sampling Air Flow Industrial Hygiene Inhalation Studies Occupational Exposure Sampling Sampling Methods
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  Michigan ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-106
• NIOSHTIC Number:
  nn:20058204
• NTIS Accession Number:
  PB2020-100157
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-002984, 2010 Apr; :1-106
• Contact Point Address:
  Professor Emeritus James H. Vincent, Ph.D., D.Sc., FRSC, Department of Environmental Health Sciences, School of Public Health, University of Michigan, 109 S. Observatory, Ann Arbor, MI 48109-2029
• Email:
  jhv@umich.edu
• Federal Fiscal Year:
  2010
• NORA Priority Area:
  Research Tools and Approaches: Exposure Assessment Methods
• Performing Organization:
  University of Michigan, Ann Arbor, Michigan
• Peer Reviewed:
  False
• Start Date:
  19940901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20090831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:3d8373e0886a06218c5536a20d7854322e3dcdab63891cd6bec40e430e037c958252b80f980bb5e01ed5cc2ad5559f3c0db40380b4868ddb3624c95d52e139f7
• Download URL:
  https://stacks.cdc.gov/view/cdc/218940/cdc_218940_DS1.pdf
• File Type:
  [PDF - 4.58 MB ]