New Evidence Raises Concerns Regarding Respiratory Protection Against Influenza

January 11, 2008 -- Researchers from the Centre d'études du Bouchet (Defense Research Center) in Vert Le Petit, France, have released a study that supports the IAFF recommendation that emergency responders use only a P-100 disposable filtering facepiece respirator with an elastomeric seal or a respirator with a higher level of respiratory protection, such as an air purifying respirator (APR) or powered air purifying respirator (PAPR) with a HEPA filter/canister, as minimum respiratory protection against influenza exposures, including the current avian flu (H5N1).

The study evaluated the efficiency of commercially available masks and respirators against Influenza A by exposing mice to an aerosol of Influenza A virus to determine if available masks and respirators (N-95) were efficient against airborne viruses. All of the mice that were protected with the equivalent of an N-95 respirator were dead within eight days.

Download an abstract of the report and a poster of the project.

Because influenza can be transmitted via the airborne (aerosol) route and, therefore, requires serious respiratory protection, the IAFF has made clear its concerns about the ability of N-95 respirators to protect against viral airborne pathogens, while others – including the U.S. government – have kept silent about this issue.

The IAFF is in the process of obtaining a full copy of the report, as it affects hundreds of millions – if not billions – of N-95 respirators that have been stockpiled worldwide.

While a respirator is not a guarantee of protection against any disease, a high-filtration respirator worn with eye protection and medical gloves (compliant to the NFPA 1999 Standard) by a trained individual, practicing good hygiene and precautions will provide a high degree of protection.

If a respirator is 95 percent effective (N-95), and there are 100,000 viruses aerosolized by a cough of a nearby patient, the N-95 respirator would allow 5,000 viruses. The infective dose of Influenza A (H5N1 is an Influenza A) is between one and 740 viruses (virions), depending on the research. Even with higher efficiency and lower exposures at each cough, the cumulative exposure for an entire shift heightens the importance of filtration performance and, of course, proper fit.

Filtration performance should be 99.99+ percent against virus challenges, with that level of effectiveness maintained throughout an eight-hour shift – or at least the length of time the user is required to wear the respirator. Such protection is afforded by a “100-series” filtering facepiece respirator or a properly filtered APR or PAPR.

This issue may become more prevalent as governments or employers try to downplay the N-95 issue. If the threat was smaller, wasting money spent on stockpiling hundreds of millions of improper respirators would not be an issue. The bottom line is that the threat does remain for the next new mutant strain of Influenza A and all first responders need to be prepared.

The IAFF will continue to monitor and address this important issue, and continue to ask that employers that are purchasing and stockpiling filtering facepiece respirators for their employees remain aware of the protection that is (or isn’t) afforded.


Additional Resources

IAFF Pandemic Flu Guidelines

“IOM Issues Report on PPE and Pandemic Flu,” International Association of Fire Fighters

“Influenza Transmission and the Role of Personal Protective Respiratory Equipment: An Assessment of the Evidence,” Council of Canadian Academies

World Organization for Animal Health Report, published by MSNBC