Respirator and Surgical Mask Performance

As part of my early filter performance studies, I tested a large number of surgical mask filters for collection of both non-biological and biological aerosols. I found that surgical mask filters vary widely in their performance and that the filter tests required by the Food and Drug Administration were entirely non-predictive because they do not employ best-practice experimental conditions to discriminate high- from low-performing filters. I was invited by NIOSH to co-author two Science Blogs describing the differences between respirators and surgical masks and explaining that filter performance for biological aerosol exposures can be predicted from tests using non-biological aerosols. While surgical masks may provide some protection from direct droplet sprays and splashes, it is a common misunderstanding that they will also prevent release and offer protection from small airborne particles. Because surgical masks are often recommended for healthcare worker protection from airborne infectious diseases, I conducted a study of surgical mask filter and fit that clearly demonstrated that, even for surgical masks with relatively “good” filter performance (but not equivalent to that of respirator filters), it is impossible to obtain a good fit. The best-fitting surgical mask showed 30% particle leakage into the facepiece. I have been an invited speaker at several IOM workshops, where I was asked to describe my research on respirator and surgical mask performance in the context of occupational exposures to TB, planning for pandemics and developing PPE for Ebola.

1. Chen SK, Vesley D, Brosseau LM, Vincent JH. Evaluation of single-use masks and respirators for protection of health care workers against mycobacterial aerosols. Am J Infect Control. 1994 Apr;22(2):65-74. PubMed PMID: 8060007.

2.  McCullough NV, Brosseau LM, Vesley D. Collection of three bacterial aerosols by respirator and surgical mask filters under varying conditions of flow and relative humidity. Ann Occup Hyg. 1997 Dec;41(6):677-90. PubMed PMID: 9375526.

3. Oberg T, Brosseau LM. Surgical mask filter and fit performance. Am J Infect Control. 2008 May;36(4):276-82. PubMed PMID: 18455048. 

Small Business Health and Safety

Since the mid-1990s I have been the co-I and PI on four randomized controlled trials of workplace health and safety interventions targeted at small businesses in the woodworking, metal fabrication and auto repair industries. Because small businesses have limited resources and rarely experience OSHA inspections, we have been exploring different models for delivering interventions that motivate owners to improve workplace conditions, programs and policies. Over time we have found the most successful intervention design is one that requires business owners to establish an employee/management safety committee, which is then trained to identify workplace hazards and their solutions. Our metal fabrication study captured the attention of a workers compensation company, which partnered with us to deliver a similar intervention in 150 small companies across the country. Most recently we partnered with several technical colleges to develop and implement new educational modules on workplace safety to students in auto collision repair and metal fabrication courses, following students throughout a two-year program into their first year of employment. 

1. Brosseau LM, Parker DL, Lazovich D, Milton T, Dugan S. Designing intervention effectiveness studies for occupational health and safety: The Minnesota Wood Dust Study. Am J Ind Med. 2002 Jan;41(1):54-61. PubMed PMID: 11757055

2.  Brosseau LM, Li SY. Small business owners' health and safety intentions: a cross-sectional survey. Environ Health. 2005 Oct 21;4:23. PubMed PMID: 16242041; PubMed Central PMCID: PMC1277835.

3. Brosseau LM, Parker DL. Interventions: advancing the state of the art. Public Health Rep. 2009 Jul-Aug;124 Suppl 1:1-3. PubMed PMID: 19618801; PubMed Central PMCID: PMC2708652.

4. Brosseau LM, Bejan A, Parker DL, Skan M, Xi M. Workplace safety and health programs, practices, and conditions in auto collision repair businesses. J Occup Environ Hyg. 2014;11(6):354-65. PubMed PMID: 24274827. 

Risk Assessment of Biological Aerosols

I have developed new approaches to risk assessment for biological aerosol exposures. I developed a “control banding” approach to selecting respirators for biological aerosol exposures that has been widely used by industrial hygienists and was most recently adopted as an appendix to the Canadian Standard for Selection, Use and Care of Respirators (CAN/CSA-Z94.4-11). In response to reports of recent emerging infectious disease impacts on healthcare workers, Dr. Jones and I developed a new weight-of-evidence approach to determining the aerosol transmissibility of an infectious organism. Most recently, I developed a control banding model for aerosol-transmissible infectious respiratory organisms, which I applied specifically to SARS-CoV-2.

1. McCullough NV, Brosseau LM. Selecting respirators for control of worker exposure to infectious aerosols. Infect Control Hosp Epidemiol. 1999 Feb;20(2):136-44. PubMed PMID: 10064221.

2. Brosseau LM. Fit testing respirators for public health medical emergencies. J Occup Environ Hyg. 2010 Nov;7(11):628-32. PubMed PMID: 20853203.

3. Harriman K, Brosseau L, Trivedi K. Hospital-associated Middle East respiratory syndrome coronavirus infections. N Engl J Med. 2013 Oct 31;369(18):1761. PubMed PMID: 24171525.

4. Jones RM, Brosseau LM. Aerosol transmission of infectious disease. J Occup Environ Med. 2015 May;57(5):501-8. PubMed PMID: 25816216.

5. Sietsema, M., Brosseau, L.M., Koonin, L., Radonovich, L., Hearl, F. A., 2019. Control Banding Framework for Protecting the U.S. Workforce from Aerosol Transmissible Infectious Disease Outbreaks with High Public Health Consequence. 17 (2), 124-132 Health Security

6. Brosseau LM, Rosen J, Harrison R. Selecting Controls for Minimizing SARS-CoV-2 Aerosol Transmission in Workplaces and Conserving Respiratory Protective Equipment Supplies. Annals of Work Exposures and Health. 2020 Aug 21.