HARSTAD, J. BRUCE (Fort Detrick, Frederick, Md.). Sampling submicron Ti bacteriophage aerosols. Appl. Microbiol. 13:899-908. 1965.-Liquid impingers, filter papers, and fritted bubblers were partial viable collectors of radioactive submicron Ti bacteriophage aerosols at 30, 55, and 85% relative humidity. Sampler differences for viable collection were due to incomplete physical collection (slippage) and killing of phage by the samplers. Dynamic aerosols of a mass median diameter of 0.2 IA were produced with a Dautrebande generator from concentrated aqueous purified phage suspensions containing extracellular soluble radioactive phosphate as a physical tracer. There was considerable destruction of phage by the Dautrebande generator; phage titers of the Dautrebande suspension decreased exponentially, but there was a progressive (linear) increase in tracer titers. Liquid impingers recovered the most viable phage but allowed considerable (30 to 48%) slippage, which varies inversely with the aerosol relative humidity. Filter papers were virtually complete physical collectors of submicron particles but were the most destructive. Fritted bubbler slippage was more than 80%. With all samplers, phage kill was highest at 85% relative humidity and lowest at 55% relative humidity. An electrostatic precipitator was used to collect aerosol samples for particle sizing with an electron microscope. The particle size was slightly larger at 85% relative humidity than at 30 or 55% relative humidity. 899 on July 3, 2020 by guest http://aem.asm.org/ Downloaded from nonu8 HARSTAD on July 3, 2020 by guest http://aem.asm.org/ Downloaded from
A new method is described for evaluating air filters with submicron aerosols. The method is unique in that the aerosols were viable, highly concentrated, and composed entirely of submicron particles (0.1 micron NMD). Tests were conducted to compare air filters in removing submicron Ti phage aerosols and bacterial aerosols of Bacillus subtilis var niger spores (1 micron NMD). Architects, engineers, and research investigators concerned with the control of submicron particles might consider filtration rather than other methods of air cleaning.
Effect of air ions on submicron Ti bacteriophage aerosols. Appl. Microbiol. 14:888-891. 1966.-The effect of a high concentration of ionized air molecules on sampling Ti phage aerosols of submicron particle size was evaluated by comparing the phage recoveries of all-glass impingers (AGI-4) and type 6 filter papers. Sampler recoveries of all ionized aerosols were less than the recoveries of nonionized control aerosols. These reductions in recovery were greater with positive ions than with negative ions or ions of mixed polarity. The AGI-4 allowed considerable slippage, which was not affected by the air ions. Type 6 filter paper recoveries were less than AGI-4 recoveries. The air ions did not appear to affect the aerosol particle size as determined by an electron microscope.
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