But the truth is, our knowledge of how influenza spreads, and what barriers work well to protect HCWs, is severely limited. Which is why a few months back the IOM (Institute of Medicine) released, through the National Academies Press, an extensive, 200+ page update on the use of PPEs that essentially calls for better science on which to base our decisions regarding the right kind of protection for HCWs. While the requisite knowledge won’t come overnight, today we have an ingenious piece of research that appears in the current issue of the IDSA’s Journal of Infectious Diseases. Not only does it compare the efficacy of surgical masks verses N95s, it gives us important new perspectives on the importance of eye protection against the influenza virus.
Masks are frequently the first things we think of when hearing about infections or bank robbers. A mask can also be a dance or used in theatre. [masks an ancient classification of disease]
But within the context of health and safety, protective masks fall within two groupings- breathing out and breathing in.
“Surgical Masks” are used to prevent the spread of exhaled germs. These masks help keep you from infecting others by breathing or speaking onto people. These are often the masks one sees on TV shows such as ER or in news photos about the SARS illnesses in China. In other cultures, using surgical masks is a polite way to prevent the spread of seasonal flu and colds in public places. Sneezing or coughing into a tissue (such as Kleenix® ) serves a similar purpose. [ or do it in your sleeve,
- Do it in your sleeve –
“Respirators”are specialized masks to prevent inhalation of particulates. They must meet certain standards to be called respirators. In the US, respirators must be “NIOSH-approved” (National Institute of Occupational Safety and Health).
N95 respirator, fitted
These images and a quick guide to respirators is included in the pamphlet available for download
⇒ It is easy to give one’s self a false sense of security by wearing a bandanna or a dust mask instead of a NIOSH-approved respirator. Your health can be damaged as a result of using the wrong type. ⇐
⇒ Masks are useful to break only the respiration route (oral-nasal) of transmitting disease. ⇐ Other types of personal protective equipment (PPE) are suitable for other transmission routes.
⇒ Poorly fitted or dirty respirators do more harm than good. ⇐
Choosing to wear a respirator or a mask involves two major considerations—
Currently (April 2006) the avian H5N1 or A(H5N1) isn’t in the birds in our region. Nowhere has the avian or bird disease transformed into the human H5N1. Therefore we are considering occupational rather than medical or emergency (pandemic) situations*.
In an occupational situation, Do you have requirements or guidelines from your agency that you should follow? If this is a personal choice, Will you be exposed occasionally or continuously to a possble contaminant? If continuously exposed, Will your activity level be quiet or vigorous? (A one-way valved respirator is a good choice for bicycling on dirt roads with other traffic, for example.) One other very important consideration, Do you have chronic lung or breathing problems, such as asthma? In this case, consult your health provider first.
If you decide you want occupational protection, you will need an “N95 disposable respirator”. See the photos below of two types, with and without a valve.
For suppliers, see
Even disposable respirators, like all safety equipment, must be kept dry and clean until ready for use. Don’t stick them in the bottom of a backpack (where they squash down to useless flatness just when it is time to bicycle back home!)
The University of North Carolina, Chapel Hill, Environment, Health & Safety Office has an on-line training, with photos, about Using N95 for Respiratory Protection
*In planning for medical and possible pandemic situations, see the World Health Organization, Pan American Health Organization or the Centers for Disease Control & Prevention recommendations.
Also look at this article about constructing an emergency respirator when no other supplies are available, Dato VM, Hostler D, Hahn ME. Simple respiratory mask [letter]. Emerg Infect Dis [serial on the Internet]. 2006 June [date cited]. Available from http://www.cdc.gov/ncidod/EID/vol12no06/05-1468.htm
Please read the following background information.
from January 2006, “What the General Public Should Know and Understand About Respirators and Avian Influenza (H5N1)”
1. Reducing exposure to the airborne influenza virus particles does not mean that the risk of exposure, infections and illness has been eliminated. Respirators will not prevent you from catching the flu in other ways such as touching your mouth, nose or eyes with contaminated hands or objects, or eating contaminated food. At this time the CDC recommends the best precaution for the general public is hand washing.
2. In order for a respirator to be most effective, you must properly wear it during the entire time you’re exposed. Removing the respirator to eat, drink, or smoke while you are in a contaminated area means you may be increasing the amount of virus particles you are breathing.
3. Fit of the respirator to your face is very important to help keep virus particles from getting inside your respirator. Particles can enter your respirator through any leaks between the respirator and your face large enough to let them in. Hair from beards and mustaches or anything that prevents the respirator directly touching your skin can prevent a proper seal. Following the fitting instructions and the instructions to check the fit that come with the respirator are very important. Achieving a good fit means more of the air you breathe goes through the respirator filter.
from 3M occupational health which makes many respirators and procedural masks.
Q. What is the difference between a respirator
and a surgical mask?
A. Respirators are designed to help reduce the wearers exposure to airborne particles. The primary purpose of a surgical facemask is to help prevent particles from being expelled by the wearer into the environment. Some surgical masks are also designed to be fl uid resistant to splash and splatter of blood and other infectious materials. Surgical facemasks are not necessarily designed to seal tightly to the face and therefore air leakage around the edges is likely. However, some respirators are designed to have the characteristics of both an approved respirator and a surgical mask.
Q. Can a valved respirator be used for protection from Avian influenza virus?
A. A valved respirator is designed to allow for easy exhalation through a one-way exhalation valve. If a person is wearing a respirator to reduce their exposure to contaminated aerosols, a respirator with an exhalation valve would be acceptable.
Q. How do I clean my respirator after use?
A. Disposable respirators should not be cleaned; dispose of the respirator immediately after use according to facility policy.
Q. Can disposable respirators be shared between people?
A. No. Disposable respirators should never be shared.
Respiratory Protection and Avian Influenza Viruses – Frequently Asked Questions for Health Care Professionals retrieved from
Q. How is avian influenza transmitted?
A. Birds that are infected with avian influenza viruses can shed virus in saliva, nasal secretions and faeces. It is believed that most cases of avian influenza infection in humans have resulted from contact with infected poultry or contaminated surfaces. In such situations, people should avoid contact with infected birds or contaminated surfaces, and should be careful when handling and cooking poultry. Strict hand hygiene must also be performed. Other means of transmission are possible, such as the virus becoming aerosolized and landing on exposed surfaces of the mouth, nose, eyes, or being inhaled.
from WHO (World Health Organization, Communicable Disease and Resonse) publication, Avian Influenza, including Influenza A (H5N1), in Humans: WHO Interim Infection Control Guideline for Health Care Facilities, Date of most recent amendment: 9 February 2006 available in pdf format here
4. Selection of respiratory protection equipment
o HCWs working with AI-infected patients should select the highest level of respiratory protection equipment available, preferably a particulate respirator. Particulate respirators are designed to protect the wearer from respiratory aerosols expelled by others, regardless of particle size.
o Use a particulate respirator that is at least as protective as U.S. NIOSH-certified N95, EU FFP2, or an equivalent. Examples of acceptable disposable particulate respirators in various parts of the world include:
o U.S. NIOSH-certified N95 (95%), N99 (99%), N100 (99.7%)
o Australia/New Zealand: P2 (94%), P3 (99.95%)
o China: II (95%), I (99%)
o Japan: 2nd class (95%), 3rd class (99.9%)
o Korea: 1st class (94%), Special (99.95%)
o EU: FFP2, FFP3
o The fit and seal of disposable particulate respirators is critical for effective function. If possible, it is recommended that fit testing be performed prior to the first use of a disposable particulate respirator determine if an acceptable fit and seal can be achieved.
o A user seal check should be performed each time a disposable particulate respirator is worn. If there is not a good fit and seal the particulate respirator will not be effective.
o HCWs with facial hair should not use a disposable particulate respirator because a good seal cannot be obtained. HCWs with facial structure abnormalities may also be unable to obtain a good seal.
o Some factors to consider when choosing particulate respirators in this setting include affordability, availability, impact on mobility, impact on patient care, potential for exposure to higher levels of aerosolized respiratory secretions, and potential for reusable particulate respirators to serve as fomites for transmission.
For information on particulate respirators, fit testing, and user seal checks, see:
Surgical and procedure masks
o Surgical or procedure masks are indicated when providing care for patients infected by droplet transmitted diseases and/or as part of facial protection during patient-care activities that are likely to generate splashes or sprays of blood, body fluids, secretions and excretions.
o Surgical and procedure masks do not offer appropriate respiratory protection against smallparticle aerosols (droplet nuclei) and should not be used unless particulate respirators are not available when dealing with airborne transmitted diseases. If a particulate respirator is not available, use a tightly fitting mask.
o There are no minimum standards or standardized testing methods for surgical mask filter efficiency, and there are a wide variety of filter efficiencies among available masks.
o Surgical and procedure masks are not designed for fit and thus do not prevent leakage around the edge of the mask when the user inhales, which is a major limitation for protection against droplet nuclei.
o Surgical masks come in two basic types: 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; the second type is pre-moulded, adheres to the head with a single elastic band and has a flexible adjustment for the nose bridge.
o Procedure masks are flat/pleated and affix to the head with ear loops. All masks have some degree of fluid resistance, but those approved as surgical masks must meet specified standards for protection from penetration of blood and body fluids.