As mask mandates resurface in some places and mask bans are proposed in others, understanding when, where, and why to wear a mask can be confusing.
Research shows that wearing a mask reduces the risk of contracting and spreading respiratory viruses. This is especially important now, as dangerous respiratory viruses like COVID-19 continue to cause severe illness, death, and long-term health complications.
Read on to learn more about how masks work, which types of masks offer the best protection, and when it’s most important to wear one.
How do masks protect against respiratory viruses?
Masks reduce the number of viral particles you breathe in or out. Masks work best when everyone is wearing one, but research shows that masks protect the wearer from contracting viruses, even when no one else is masking.
And if you’re sick with a virus, wearing a mask can prevent you from spreading germs to others.
What types of masks are there, and how effective are they?
Different types of masks have different degrees of effectiveness. Disposable options include:
- N95 masks: These masks are approved by the National Institute for Occupational Safety and Health (NIOSH) and filter at least 95 percent of viral particles. Out of all disposable masks, N95 masks offer the highest level of protection because they fit tightly on the wearer’s face and filter out both large and small particles. A recent study found that N95 masks are nearly perfect at blocking the spread of COVID-19 viral particles from infected wearers. To ensure that your N95 mask is NIOSH-approved and not counterfeit, look for a testing and certification approval number starting with the letters “TC” printed on the side.
- KN95 masks: While these masks are not approved by NIOSH, they meet the Chinese filtration standard and—like N95 masks—have been shown to filter at least 95 percent of viral particles. However, since KN95 masks are typically secured with ear loops rather than head straps, they may not fit the wearer’s face as effectively as N95 masks.
- Surgical masks: These masks fit loosely and only filter out large particles, making them less effective at protecting against viruses like COVID-19. However, wearing a surgical mask is better than wearing no mask at all. Surgical masks should be thrown out after every use.
You can safely reuse an N95 or KN95 mask after storing it in a paper bag for five to seven days. However, if you’ve been in an environment where a high amount of viral particles is expected—for example, if you’ve been interacting with a person who currently has a respiratory virus or if you’ve spent time in a hospital—you should discard your disposable mask immediately after wearing it. You should also discard your disposable mask if it no longer fits securely on your face.
There are also reusable masks. Two widely used options include:
- Flo Masks: These NIOSH-approved reusable masks come in a variety of shapes and sizes and have silicone gaskets for a tight seal. Their filters should be discarded and replaced after eight hours of wear for children’s masks and after 20-40 hours of wear for adult masks. While Flo Masks are more expensive than other options, they’re extremely effective: The manufacturer’s Pro Filter line filters out more than 99 percent of viral particles.
- Cloth masks: Cloth masks are made from a variety of materials and are less effective than Flo Masks, N95 masks, KN95 masks, and surgical masks at preventing respiratory virus transmission. If your cloth mask has a pocket for a filter, adding a filter can boost your protection.
How do I know if my mask fits correctly?
When choosing a high-quality mask, make sure that the mask fits tightly against your face, that no air can enter or exit your mask through the sides or around the bridge of your nose, and that you can still breathe comfortably.
You can check the seal of your mask by holding your hands above your mask while blowing air up and holding your hands below your mask while blowing air down. If you can feel your breath against your hands, your mask does not have an effective seal.
Tighten the ear loops or head straps and try again until you can’t feel your breath escaping from the mask. If you’re still feeling air, you may need to try a different mask brand or style that will better fit your face.
Where can I get high-quality masks for free?
If you are unable to afford N95 or KN95 masks, you may be able to get them for free from your local health clinic or from mask blocs—mutual aid groups that deliver free masks in their communities. You can find a mask bloc near you at MaskBloc.org.
Where and when is it most important to wear a mask?
Masks are useful anywhere, anytime to reduce the spread of respiratory viruses. Getting sick is inconvenient and potentially dangerous for everyone. Plus, you never know who around you may be immunocompromised or face other risk factors.
The Centers for Disease Control and Prevention says it’s most important to mask when:
- You’re in a public space where cases of respiratory viruses are high.
- You or the people around you are sick or were recently exposed to a respiratory virus.
- You or the people around you are at risk of severe illness.
- You travel, especially when you’re traveling by plane or using other forms of public transportation.
You may also consider masking in crowded spaces like hospitals, stores, and entertainment venues to protect yourself and those around you.
For more information, talk to your health care provider.