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“Facemasks” are sometimes used in an attempt to prevent the spread of airborne diseases such as influenza (the flu). This factsheet presents information about the different types of facemasks and their uses and limitations.
Can Facemasks Prevent Disease?
Infectious diseases such as influenza (the flu) can be spread by several methods, including:
Airborne droplets or sprays
Hand to mouth/nose/eye contact
Direct surface contact
Combinations of these methods
Because recent evidence suggests that inhalation of microscopic airborne particles may also transmit some diseases, it has been suggested that masks might reduce disease transmission.
What Types of Masks are Available?
Two general types are available:
Some N95 FFR masks have been cleared by the Food and Drug Administration (FDA) for use by the general public in public health medical emergencies. However, no study has shown that a FFR or a SM alone will effectively reduce disease transmission when worn by people in the general public who may come into contact with sick people.
Current recommendations for the use of FFR or SM are based on what is known about how these devices perform in the workplace.
Surgical Masks (SM)
A surgical mask can:
SMs are not designed to reduce the inhalation of small airborne particles that may contain infectious organisms.
Do not expect a SM to protect you from inhaling infectious organisms.
Disposable N95 Filtering Facepiece Respirators (FFR)
N95 FFRs are designed and tested to filter small particles from the air. This can reduce the number of infectious particles you inhale and might reduce your chance of infection.
Proper Fit Is Critical For Protection
N95 FFRs are designed to seal against your face to help reduce the amount of infectious particles that can enter your nose or mouth. When N95 FFRs are used in a workplace, particle concentrations inside the FFR are typically at least ten times lower than particle concentrations in the workplace air if the respirator fits the wearer. Workers receiving this level of protection have been trained in proper use of the FFR and have passed an individual fit-test.
Unfortunately, there may be little benefit from wearing an N95 FFR that has not been fit-tested on the wearer. Effective fit-tests may be difficult to obtain for members of the general public.
N95 FFRs Can Only Protect when Worn
The benefit of using any respirator, including a properly fitting N95 FFR, is quickly lost if it is not worn at all times the hazard is present. Most of the benefit of wearing a respirator is lost unless it is worn at least 90 percent of the time.
Infections and aerosols are invisible, so there is no indication when they are present. Also, some sick people may produce particles that can infect others before they show any symptoms themselves. Therefore, it is very easy to receive a significant exposure without knowing.
Even taking the respirator off to talk or eat in an area where infectious particles are present might allow enough exposure to cause infection. The only way to avoid this problem is to properly wear the respirator at all times the infectious aerosol might be in the air.
All of the respirator manufacturer’s instructions for putting on and wearing the FFR must be followed.
Respirators Alone will not Prevent Disease Transmission
Some diseases may be transmitted via small aerosols that N95 FFRs can filter out. However, droplets or sprays, hand to mouth/nose/eye contact, and direct surface contact may also cause infection.
All routes of exposure must be avoided to the greatest extent possible to reduce your chance of getting sick.
While wearing a properly fitted N95 FFR can reduce inhalation exposures, frequent hand washing with soap and water can help minimize transmission through other exposure routes.
An annual seasonal flu vaccination is the best way to reduce the chances that you will get seasonal flu.
Key Facts About Respirator Effectiveness
- A respirator that is not worn will not provide protection.
- Wearing a respirator the wrong way will result in ineffective protection.
- Wearing a respirator that fits properly all of the time provides the most effective protection.
- The protection a respirator provides is quickly lost when not worn at all times.