Face masks and respirators: Can they prevent viruses like H1N1 (Swine flu)?

Heidi Mallis

October 2009

With flu season upon us, many people are wondering what precautions they can take to prevent transmission of the H1N1 (swine flu) virus. Frequent hand washing is definitely helpful, but what about protective gear, such as gloves and masks? Do masks and respirators really protect against H1N1? Before rushing out to buy either, take a moment to read the information below.

Facemasks, which refer to disposable masks like the ones health workers occasionally wear, are designed to block large particle droplets, splashes, and sprays from reaching the wearer’s mouth and nose.1 They are intended to be used once (for whatever period of time) and then discarded. Facemasks do not form a tight seal around the nose and mouth and so they can’t protect you from very small particles in the air transmitted by coughs or sneezes (such as virus particles that can be breathed in by the user).2, 3 Another problem with facemasks is that people forget to use them consistently to protect against the flu, sometimes because they find them uncomfortable. For instance, a study conducted in 2008 by researchers in Australia found that facemasks used in households to prevent transmission of the flu virus were not effective, primarily because people didn’t use them regularly.4

Unlike facemasks, respirators form a tight seal to the face. Respirators typically refer to CDC-certified N95 or higher filtering face pieces (meaning that they filter out 95% of airborne particles). They are primarily manufactured for use in construction and industrial jobs that expose workers to dust and small airborne particles.1 In order for respirators to be effective, they must be fitted properly according to the Occupational Safety and Health Administration (OSHA) guidelines.5 Respirators are harder than facemasks to breathe through for extended periods of time and can cause skin irritation. CDC guidelines do not suggest respirators for children or people with facial hair.

A study conducted by Dr. William Lindsley at the West Virginia University Urgent Care Clinic in February 2009 found that a surgical facemask admitted 20% of respiratory particles given off by a coughing simulator (a machine) placed six feet away. In contrast, the N95 respirator blocked nearly all respiratory particles.6 Since airborne biological agents such as viruses are particles, they can be filtered by particulate respirators such as the N95.7 However, it is important to note that there is currently no available scientific data that establishes the effectiveness of particulate respirators in specifically blocking H1N1 virus particles. By the time studies are done to find out how effective respirators really are, flu season is likely to be over.

Due to the limited supply of both facemasks and respirators each flu season, the CDC recommends that these be used only in occupational health care settings by a professional looking after a patient with “known, probable, or suspected H1N1 infection.”2 Experts assume these protections will be helpful but will not provide complete protection against infection.

Given this information, how can you best protect yourself and your loved ones?
The U.S. Department of Health and Human Services (HHS) recommends a comprehensive flu prevention strategy to reduce your risk of infection. This includes:

  • Vaccination: The CDC is encouraging people to get vaccinated both for the seasonal flu and the H1N1 virus. Looking to find your closest flu clinic? Check out the American Lung Association’s Flu Clinic locator site: http://www.lungusa.org/site/pp.aspx?c=aqKGLXOAIlH&b=1015035
  • Cover your nose and mouth with a tissue when coughing or sneezing. If you do not have one available, cough or sneeze into your elbow instead of your hand. Your elbow does not touch as many things (door handles, keyboards, telephones) or people as your hand does!
  • Wash your hands often with soap and warm water (for at least 15-20 seconds) or use an alcohol-based cleaner
  • Avoid close contact with people who are sick
  • If you become ill, stay home until you are symptom-free for at least 24 hours8

These preventive strategies will greatly reduce your risk of H1N1. An ounce of prevention this flu season can help you and your loved ones stay happy, healthy, and symptom-free.

References:

1. U.S. Food and Drug Administration (2009, June 18). Masks and N95 Respirators. Retrieved from http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/MedicalToolsandSupplies/PersonalProtectiveEquipment/ucm055977.htm (Accessed October 5, 2009).

2. Centers for Disease Control and Prevention (2009, September 24). Interim recommendations for facemask and respirator use to reduce 2009 Influenza A (H1N1) virus transmission. http://www.cdc.gov/h1n1flu/masks.htm (Accessed September 29, 2009).

3. Johnson DF, Druce JD, Birch C, Grayson ML (2009, July 15). A quantitative assessment of the efficacy of surgical and N95 masks to filter influenza virus in patients with acute influenza infection. Clinical Infectious Diseases, 2009; 49:275-277.

4. MacIntyre CR, Dwyer DE, et al (2009, February). Face mask use and control of respiratory virus transmission in households. Emerging Infectious Diseases, 15(2).

5. Occupational Safety and Health Administration (2004, August 4). Fit testing procedures. United States Department of Labor. http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9780 (Accessed September 29, 2009).

6. Lindsley WG. Measurements of airborne influenza in an urgent care clinic and efficacy of masks and N95 respirators against cough aerosols in a simulated examination room. http://www.iom.edu/Object.File/Master/72/319/Lindsley%20-%20Panel%202.pdf (Accessed September 29, 2009).

7. Occupation Safety and Health Administration (2007, February 1). Guidance on preparing workplaces for an influenza pandemic. Retrieved from http://www.osha.gov/Publications/influenza_pandemic.html (Accessed October 5. 2009).

8. U.S. Department of Health and Human Services (2009). Flu: Prevention and Treatment. Retrieved from http://flu.gov/individualfamily/prevention/index.html (Accessed October 5, 2009).