Sampling methodologies and dosage assessment techniques for submicrometre and ultrafine virus aerosol particles

Abstract

Aims:The aerosolization and collection of submicrometre and ultrafine virus particles were studied with the objective of developing robust and accurate methodologies to study airborne viruses. Methods and Results: The collection efficiencies of three sampling devices used to sample airborne biological particles -the All Glass Impinger 30, the SKC BioSamplerÒ and a frit bubbler -were evaluated for submicrometre and ultrafine virus particles. Test virus aerosol particles were produced by atomizing suspensions of single-stranded RNA and double-stranded DNA bacteriophages. Size distribution results show that the fraction of viruses present in typical aqueous virus suspensions is extremely low such that the presence of viruses has little effect on the particle size distribution of atomized suspensions. It has been found that none of the tested samplers are adequate in collecting submicrometre and ultrafine virus particles, with collection efficiencies for all samplers below 10% in the 30-100 nm size range. Plaque assays and particle counting measurements showed that all tested samplers have time-varying virus particle collection efficiencies. A method to determine the size distribution function of viable virus containing particles utilizing differential mobility selection was also developed. Conclusions: A combination of differential mobility analysis and traditional plaque assay techniques can be used to fully characterize airborne viruses. Significance and Impact of the Study: The data and methods presented here provide a fundamental basis for future studies of submicrometre and ultrafine airborne virus particles.

Viable influenza A virus in airborne particles expelled during coughs versus exhalations

“…Third, the particle collection efficiency of the SKC BioSampler decreases from about 96% for 1 μm aerosol particles to about 50% for 0·3 μm particles and 10% for 0·1 μm particles 32, 33, 34. Thus, many of the smallest particles carrying influenza virus may not have been collected in our experiments.…”

“…Aerosol particles were collected using an SKC BioSampler with a 5‐ml vessel (#225‐9593, SKC) containing 5 ml of viral transport media (VTM) consisting of Hank's balanced salt solution (HBSS; Invitrogen) supplemented with 0·1% bovine serum albumin (BSA; Sigma‐Aldrich), 100 units/ml penicillin G, and 100 units/ml streptomycin (Invitrogen). The particle collection efficiency for the SKC BioSampler (i.e., the percentage of particles of a given size that are collected by the sampler) is approximately 10% for particles with aerodynamic diameters of 0·1 μm; 50% for 0·3 μm particles; 96% for 1 μm particles; 100% for 2 μm particles; and 50% for 8 μm particles 32, 33, 34. Particles larger than 10–15 μm are expected to be removed by the sampler elbow and not collected.…”

Performance of Conventional and Antimicrobial-Treated Filtering Facepiece Respirators Challenged with Biological Aerosols

“…2 assumes an AGI-30 collection efficiency (E) of 100%. It has been shown that E can be < 10% in the 10-300 nm size range (20) ; however, given that E would appear in both the numerator and denominator of Eq. 4, it will cancel out and thus have no effect on PEN results.…”

“…It has been observed that viable MS2 virions are present in aerosol particles from 25 to 407 nm in diameter. (20) …”

“…The physical penetration correction factor (CF P ) was applied to compensate for unequal sampling train particle loss bias as described in detail in Lore et al (19) Viable Penetration All glass impingers (AGI-30; ACE Glass Inc., Vineland, N.J.) were chosen to sample the viable bioaerosols as they are a good compromise between collection efficiency, collection stress on microorganism viability, and volumetric sampling rate. (13,(20)(21)(22) The PEN V of each bioaerosol was measured by sampling its viable concentration upstream and downstream of each test FFR into an AGI-30 connected to the appropriate sampling port. Each AGI-30 was filled with 20 mL of either 1 × PBS for MS2 and B. atrophaeus bacteria or deionized water for B. atrophaeus spores.…”