A Particle is a Particle

For decades, respirator researchers have been asked whether filters need to be tested with aerosols similar to those encountered in the environment. Common sense suggests that viruses or bacteria are collected differently from engineered nanoparticles, silica dusts, oil mists or other types of workplace aerosols. But that is not necessarily the case. (2016)

View A Particle is a Particle (July 2016)
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NIOSH Science Blog

Do We Need to Challenge Respirator Filters With Biological Aerosols? (2014)
The purpose of this NIOSH Science Blog is to explain what is currently known about an important aspect of respirator filtration. For decades, respirator researchers have been asked whether filters need to be tested with aerosols similar to those encountered in the environment. Common sense suggests that viruses or bacteria are collected differently from engineered nanoparticles, silica dusts, oil mists or other types of workplace aerosols.

Further Reading

1. McCullough, N., L. Brosseau, and D. Vesley: Collection of three bacterial aerosols by respirator and surgical mask filters under varying conditions of flow and relative humidity. Annals of occupational hygiene 41(6): 677-690 (1997).
2. Hofacre, K.C., A.W. Richardson, J.P. Eshbaugh, and P.D. Gardner: “Respirator filter efficiency testing against particulate and biological aerosols under moderate to high flow rates.” Edgewood Chemical Biological Center ECBC-CR-085, 2006. [Available at NIOSH Docket #272].
3. Harnish, D., B. Heimbuch, M. Husband, A. Lumley, K. Kinney, R. Shaffer et al.: Challenge of N95 Filtering Facepiece Respirators with Viable H1N1 Influenza Aerosols. Infection control and hospital epidemiology: the official journal of the Society of Hospital Epidemiologists of America 34(5): 494 (2013).
4. Hinds, W.C.: Aerosol technology: properties, behavior, and measurement of airborne particles: John Wiley & Sons, 2012.
5. Fisher, E.M., A.W. Richardson, S.D. Harpest, K.C. Hofacre, and R.E. Shaffer: Reaerosolization of MS2 bacteriophage from an N95 filtering facepiece respirator by simulated coughing. Annals of occupational hygiene 56(3): 315-325 (2012).
6. Kennedy, N.J., and W.C. Hinds: Release of simulated anthrax particles from disposable respirators. J Occup Environ Hyg 1(1): 7-10 (2004).
7. Shaffer, R.E., and S. Rengasamy: Respiratory protection against airborne nanoparticles: a review. Journal of nanoparticle research 11(7): 1661-1672 (2009).
8. Stevens, G.A., and E.S. Moyer: “Worst case” aerosol testing parameters: I. Sodium chloride and dioctyl phthalate aerosol filter efficiency as a function of particle size and flow rate. The American Industrial Hygiene Association Journal 50(5): 257-264 (1989).
9. Moyer, E.S., and G.A. Stevens: “Worst-Case” Aerosol Testing Parameters: III. Initial Penetration of Charged and Neutralized Lead Fume and Silica Dust Aerosols through Clean, Unloaded Respirator Filters. The American Industrial Hygiene Association Journal 50(5): 271-274 (1989).
10. Eshbaugh, J.P., P.D. Gardner, A.W. Richardson, and K.C. Hofacre: N95 and P100 respirator filter efficiency under high constant and cyclic flow. Journal of Occupational and Environmental Hygiene 6(1): 52-61 (2008).
11. Oberg, T., and L.M. Brosseau: Surgical mask filter and fit performance. American journal of infection control 36(4): 276-282 (2008).
12. Rengasamy, S., A. Miller, B.C. Eimer, and R.E. Shaffer: Filtration performance of FDA-cleared surgical masks. Journal of the International Society for Respiratory Protection 26(1): 54 (2009).
13. Brosseau, L.M., N.V. McCullough, and D. Vesley: Mycobacterial aerosol collection efficiency of respirator and surgical mask filters under varying conditions of flow and humidity. Applied occupational and environmental hygiene 12(6): 435-445 (1997).
14. NIOSH: “NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84.” [Online] Available at https://www.cdc.gov/niosh/docs/96-101/, (1996).
15. Janssen, L., H. Ettinger, S. Graham, R. Shaffer, and Z. Zhuang: Commentary: The Use of Respirators to Reduce Inhalation of Airborne Biological Agents. Journal of Occupational and Environmental Hygiene 10(8): D97-D103 (2013).
16. Zayas, G., M.C. Chiang, E. Wong, F. MacDonald, C.F. Lange, A. Senthilselvan et al.: Cough aerosol in healthy participants: fundamental knowledge to optimize droplet-spread infectious respiratory disease management. BMC pulmonary medicine 12(1): 11 (2012).
17. Baron, P.: “Generation and Behavior of Airborne Particles (Aerosols).” [Online] Available at https://www.cdc.gov/niosh/topics/aerosols/pdfs/Aerosol_101.pdfpdf icon, (2010).
18. NIEH: “Particles: Size Makes All the Difference.” [Online] Available at http://www.niehs.nih.gov/health/assets/docs_a_e/ehp
19. Harnish-DA; Heimbuch-BK; Balzli-C; Choe-M; Lumley-AE; Shaffer-RE; Wander-JD: Capture of 0.1-um aerosol particles containing viable H1N1 influenza virus by N95 filtering facepiece respiratorsexternal icon.J Occup Environ Hyg 2016 Mar; 13(3):D46-D49
20. Harnish-DA; Heimbuch-BK; Husband-M; Lumley-AE; Kinney-K; Shaffer-RE; Wander-JD: Challenge of N95 filtering facepiece respirators with viable H1N1 influenza aerosolsexternal icon.Infect Control Hosp Epidemiol 2013 May; 34(5):494-499