Technologies for Estimating Viable Spores in an Aerosol Particle


  1. Ho, J.
  2. Ogston, J.
  3. Spence, M.
Corporate Authors
Defence Research Establishment Suffield, Ralston ALTA (CAN)
There are practical and valid reasons to present biological field trial reference results as agent containing particles per liter of air (ACPLA). One fundamental characteristic of a biological threat aerosol is that the agent particles must be linked to infectivity. To be labeled as infectious, each individual particle must grow and replicate either in a host or in artificial medium. The slit sampler approach, using nutrient growth medium for particle number measurement is still the best method to approximate this relationship. However, it must be pointed out that each colony that forms on growth medium can arise from a single viable organism or an aggregate consisting of two or more individuals. It has been written that in considering threat biological aerosols, the aggregates are more relevant with respect to respirable particle studies (Day, 1981). Other biological samplers like the glass impinger (Terzieva et al. 1996) measure individual viable organisms in air. Without knowledge of the number of viable organisms per particle, comparing results from these samplers is difficult. If this number were several orders of magnitude greater than unity, misconceptions may arise in interpreting ACPLA figures, especially in threat assessment scenarios. TRUNCATED
Aerosol detection;ACPLA (Agent Containing Particles per Liter of Air);Viable cells;Slit samplers
Report Number
DRES-TR-1999-136 — Technical Report
Date of publication
01 Nov 1999
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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