interim Recommendations for Facemask and Respirator Use to Reduce Novel Influenza A (H1N1) Virus Transmission

May 27, 2009 6:30 PM ET

This document provides updated interim guidance on the use of facemasks and respirators for decreasing the exposure to novel influenza A (H1N1) virus. This guidance replaces other CDC guidance on mask and/or respirator use that may be included in other CDC documents in regards to the outbreak of novel H1N1 virus. No change has been made to guidance on the use of facemasks and respirators for health care settings. This document includes guidance on facemask and respirator use for a wider range of settings than was included in previous documents and includes recommendations for those who are at increased risk of severe illness from infection with the novel H1N1 virus compared with those who are at lower risk of severe illness from influenza infection.For more information about human infection with novel influenza A (H1N1) virus, visit the CDC H1N1 Flu website. Other CDC novel H1N1 guidance will be updated with the information contained in this document as soon as possible.

Detailed background information and recommendations regarding the use of facemasks and respirators in non-occupational community settings can be found on PandemicFlu.gov in the document Interim Public Health Guidance for the Use of Facemasks and Respirators in Non-Occupational Community Settings during an Influenza Pandemic. Information on the use of facemasks and respirators in health care settings can be found at http://www.cdc.gov/h1n1flu/guidelines_infection_control.htm.

Information on the effectiveness of facemasks and respirators for decreasing the risk of influenza infection in community settings is extremely limited. Thus, it is difficult to assess their potential effectiveness in decreasing the risk of novel influenza A (H1N1) virus transmission in these settings. In the absence of clear scientific data, the interim recommendations below have been developed on the basis of public health judgment, the historical use of facemasks and respirators in other settings for preventing transmission of influenza and other respiratory viruses, and on current information on the spread and severity of the novel influenza A (H1N1) virus.

In areas with confirmed human cases of novel influenza A (H1N1) virus infection, the risk for infection can be reduced through a combination of actions. No single action will provide complete protection, but an approach combining the following steps can help decrease the likelihood of transmission. These recommended actions are:

• Wash hands frequently with soap and water or use alcohol-based hand cleaner when soap and water are not available.
• Cover your mouth and nose with a tissue when coughing or sneezing.
• Avoid touching your eyes, nose and mouth
• People who are sick with an influenza-like illness (ILI) (fever plus at least cough or sore throat and possibly other symptoms like runny nose, body aches, headaches, chills, fatigue, vomiting and diarrhea) should stay home and minimize contact with others, including avoiding travel, for 7 days after their symptoms begin or until they have been symptom-free for 24 hours, whichever is longer.
• Avoid close contact (i.e. being within about 6 feet) with persons with ILI.

In addition, influenza antiviral medications are an important tool for the treatment and prevention of influenza, including novel H1N1. Also see Guidance on the use of antiviral medications.

Facemasks and Respirators

Recommendations for the uses of facemasks and/or respirators are listed in Table 1 below for different settings where a person may be exposed to novel H1N1 virus. These recommendations also differ based on whether the person exposed to novel H1N1 is in a group at increased risk for severe illness from influenza infection. More information on preventing influenza transmission in health care settings can be found in the Interim Guidance for Infection Control for Care of Patients with Confirmed or Suspected Novel Influenza A (H1N1) Virus Infection in a Healthcare Setting.

In community and home settings, the use of facemasks and respirators generally are not recommended. However, for certain circumstances as described in Table 1, a facemask or respirator may be considered, specifically for persons at increased risk of severe illness from influenza.

Use of N95 respirators or facemasks generally is not recommended for workers in non-healthcare occupational settings for general work activities. For specific work activities that involve contact with people who have ILI, such as escorting a person with ILI, interviewing a person with ILI, providing assistance to an individual with ILI, the following are recommended:

• workers should try to maintain a distance of 6 feet or more from the person with ILI;
• workers should keep their interactions with ill persons as brief as possible;
• the ill person should be asked to follow good cough etiquette and hand hygiene and to wear a facemask, if able, and one is available;
• workers at increased risk of severe illness from influenza infection (see footnote 3 of table 1) should avoid people with ILI (possibly by temporary reassignment); and,
• where workers cannot avoid close contact with persons with ILI, some workers may choose to wear a facemask or N95 respirator on a voluntary basis.

In the occupational healthcare setting, respiratory protection is recommended. Because infection control precautions, including respiratory protection, are imperfect, workers who are at increased risk of severe illness from influenza, and who are caring for a patient with known, probable, or suspected novel H1N1 or ILI, may consider temporary reassignment to avoid exposure.

Additional recommendations for use of facemasks by people who have ILI that may be due to novel H1N1 infection are included in Table 2.

There are important differences between facemasks and respirators. Facemasks do not seal tightly to the face and are used to block large droplets from coming into contact with the wearer’s mouth or nose. Most respirators (e.g. N95) are designed to seal tightly to the wearer’s face and filter out very small particles that can be breathed in by the user. For both facemasks and respirators, however, limited data is available on their effectiveness in preventing transmission of H1N1 (or seasonal influenza) in various settings. However, the use of a facemask or respirator is likely to be of most benefit if used as early as possible when exposed to an ill person and when the facemask or respirator is used consistently. (Ref. 1. MacIntyre CR, et al. EID 2009;15:233-41. 2. Cowling BJ, et al. Non-pharmaceutical interventions to prevent household transmission of influenza. The 8th Asia Pacific Congress of Medical Virology, Hong Kong, 26-28 February 2009.)

Facemasks: Unless otherwise specified, the term ”facemasks” refers to disposable facemasks cleared by the U.S. Food and Drug Administration (FDA) for use as medical devices. This includes facemasks labeled as surgical, dental, medical procedure, isolation, or laser masks. Such facemasks have several designs. One type is affixed to the head with two ties, conforms to the face with the aid of a flexible adjustment for the nose bridge, and may be flat/pleated or duck-billed in shape. Another type of facemask is pre-molded, adheres to the head with a single elastic band, and has a flexible adjustment for the nose bridge. A third type is flat/pleated and affixes to the head with ear loops. Facemasks cleared by the FDA for use as medical devices have been determined to have specific levels of protection from penetration of blood and body fluids. Facemasks help stop droplets from being spread by the person wearing them. They also keep splashes or sprays from reaching the mouth and nose of the person wearing the facemask. They are not designed to protect against breathing in very small particle aerosols that may contain viruses. Facemasks should be used once and then thrown away in the trash.

Respirators: Unless otherwise specified, "respirator" refers to an N95 or higher filtering face piece respirator certified by the CDC/National Institute for Occupational Safety and Health (NIOSH). A respirator is designed to protect the person wearing the respirator against breathing in very small particle aerosols that may contain viruses. A respirator that fits snugly on the face can filter out virus-containing small particle aerosols that can be generated by an infected person, but compared with a facemask it is harder to breathe through a respirator for long periods of time. Respirators are not recommended for children or people who have facial hair.

Where respirators are used in a non-occupational setting, fit testing, medical evaluation and training are recommended for optimal effectiveness.

When respiratory protection is required in an occupational setting, respirators must be used in the context of a comprehensive respiratory protection program as required under OSHA’s Respiratory Protection standard (29 CFR 1910.134). This includes fit testing, medical evaluation and training of the worker. When required in the occupational setting, tight-fitting respirators cannot be used by people with facial hair that interferes with the face seal.

When respirators are used on a voluntary basis in an occupational setting, requirements for voluntary use of respirators in work sites can be found on the OSHA website.

Employers should continue to evaluate workplace hazards related to the novel H1N1 influenza A situation in accordance with CDC and OSHA guidance. Mandatory use of respiratory protection may be required when work activities in occupational settings confer risk that is task/function based, and risk analyses conducted by the employer could identify hazardous work activities. For example, performing activities which generate large amounts of aerosols require respiratory protection regardless of the setting in which it is performed (i.e. in a hospital, an outpatient setting, a prison).

For additional information on facemasks and respirators, see the CDC/NIOSH website, the Food and Drug Administration website, and the Occupational Safety and Health Administration website.