Development of an Aerosol System for Uniformly Depositing Bacillus anthracis Spore Particles on Surfaces

Details

• Personal Author:
  Baron, Paul A. ; Beard JK ; Dahlstrom GE ; Deye GJ ; Estill, Cheryl F. ; Hein, Misty J. ; Larsen LD
• Description:
  After the anthrax incidents in October 2001, several techniques used for sampling surfaces for biological agents were found to be inadequately validated, especially at low surface loadings. Therefore a test chamber was developed to produce sample sets having targeted surface concentrations of dry biological agent simulant. Dry spore aerosols were initially dispersed into the chamber at relatively high air concentrations, and monitored in real time. The concentration decay (due to stirred settling and dilution) was measured and when the targeted air concentration was reached, the sampling surfaces were uncovered and exposed to the settling particles until >99% of the particles had settled. Multiple agar plates were used to estimate the true colony-forming-unit (CFU) surface concentration. The uniformity of surface loadings was limited by random deposition of small numbers of particles on the surfaces (Poisson distribution) and was characterized by how much greater the observed variability was than that predicted by Poisson statistics. The flow-enhanced powder mixture appeared to affect the spores' ability to grow on the agar medium. Three ways of analyzing the agar plates were used to evaluate the effect of spore coatings on viability and to differentiate between number of spore-containing particles and the number of spores. The presence of spore agglomerates re-suspended by various sample handling activities in the chamber further increased the variability of deposited particles. Based on estimated airborne particle concentration, it was possible to predict mean agar plate concentrations within narrow confidence intervals (CI) at low (4.8 CFU, 95% CI 3.5-6.4), medium (20 CFU, 95% CI 17-23), and high (160 CFU, 95% CI 140-190) concentrations. [Description provided by NIOSH]
• Subjects:
  Aerosols Bacteria Biological Products Dust Environmental Monitoring Occupational Health Safety
• Keywords:
  Aerosol-particles Aerosol-sampling Air-monitoring Air-sampling Analytical-processes Bacterial-dusts Biological-agents Monitoring-systems Sampling Simulation-methods Surface-properties

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• ISSN:
  0278-6826
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  Ohio ; OSHA Region 5 ; OSHA Region 8 ; Utah
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DART - Division of Applied Research and Technology ; DSHEFS - Division of Surveillance, Hazard Evaluations, and Field Studies
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  159-172
• Volume:
  42
• Issue:
  3
• NIOSHTIC Number:
  nn:20033477
• Citation:
  Aerosol Sci Technol 2008 Mar; 42(3):159-172
• Federal Fiscal Year:
  2008
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  True
• Source Full Name:
  Aerosol Science and Technology
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:0cd4b0a8f3415e83fd953e9f542e69cc133cc3a1a449b851ff0cb358153b0b0c3ec569ab23aebe248729523fd198caae562fb08db403b03ab291b8b97b5d3817
• Download URL:
  https://stacks.cdc.gov/view/cdc/189036/cdc_189036_DS1.pdf
• File Type:
  [PDF - 1.53 MB ]