The virus that causes COVID-19 has become more contagious over time. This is why the Cambridge Public Health Department recommends using high quality disposable masks—not cloth masks—for the best protection in indoor settings.
New research shows that high-quality “medical-style” masks offer the best protection to the wearer from infection.
Look for masks that fit snugly and block at least 90% of small viral particles from being breathed in. Masks should also be comfortable, especially if they are being worn throughout the day.
To find out where to buy high-quality masks, see the CPHD guide Shopping for a High-Quality Mask.
Wear a mask with excellent filtration. Aim for 90-95%.
- Several types of disposable masks available to the public provide excellent personal protection. These “high filtration” masks include KF94 masks (made in Korea), KN95 masks (made in China) and flat medical-style masks that are quality-certified.
- KN95 and KF94 fit more snugly, depending on face-shape, than flat medical-style masks.
- If shopping for masks, some keywords to look for are KF94, KN95, or ASTM-rated.
- About Cloth Masks: Cloth masks are best suited to outdoor use when it’s easy to social distance. They do not provide adequate protection against the Omicron variant in indoor settings.
More information on pros and cons of different types of masks is available on the CDC website.
Choose masks that fit snugly and cover your nose, mouth, and chin.
- All edges should touch your skin so that unfiltered air does not escape or enter through the gaps.
- Try different shaped masks to fit your face.
- Try “ear savers” or mask straps to change the way a mask fits on your face.
- A bendable nose clip is important for keeping masks in place and closing gaps.
- If you cannot get a good fit with a flat medical-style mask, consider placing a cloth mask over it. This is known as “double masking.”
- See the CDC website for more tips on improving mask fit and double-masking.
Mask Reuse and Care
- High quality disposable masks can be reused many times, as long as they are not visibly damaged or soiled. In independent tests, these masks remained effective after 40 hours or more of use.
- Masks that have been filtering germs all day may have germs on their outside surface. When removing a mask, hold it by the ear loops and wash your hands afterwards.
- Store used disposable masks in the open air or a paper bag to dry until you need them.
- Do not clean your disposable masks with soap or alcohol—or put them in the washing machine—because this will destroy their ability to block viral particles. Medical-style flat masks and KF94/KN95 masks still work when wet with perspiration. They can be dried with a tissue.
- Bacteria and fungi can grow on cloth masks, so they need to be washed daily with your laundry or in hot soapy water in the sink.