More Effective Masks
To Help Prevent the Spread of COVID-19
Based on research and guidance from the Cambridge Public School Department
Updated 2022-01-18
What do I need to Know?
Not all masks protect equally. New COVID variants are much more transmissible, and many commonly-used masks don't effectively block virus particles.
For our unvaccinated young kids who need to spend time indoors, use of effective masks is particularly important.
Filtration - Types of Masks
Cloth masks block only 5-30% of small particles. Many "medical-looking" masks that are not ASTM-rated surgical masks typically block only 10% of small particles.
High-quality masks (such as KF94 and KN95, and N95) block 90-99% of small particles, are are more breathable than cloth, and KF94 and KN95 masks are available in both child and adult sizes. ASTM-rated surgical masks also have good filtration but aren’t designed to fit snugly and so provide less protection from aerosols that are floating around a room.
These better masks are inexpensive, don't get soggy like cloth, and can be worn for 40+ hours without losing effectiveness as long as they are not damaged or dirty. Just let masks air out (ideally for multiple days) between uses. Do not wash or treat them with chemicals, which can harm filtration.
Fit
Air-tight fit is critical! Masks must have an air-tight fit with no gaps around the nose or on the sides -- otherwise air will go around the mask instead of through the filter material.
Tri-fold (AKA "3D" / "boat" / "fish type") or bi-fold (AKA "2D") masks often provide an air-tight fit more easily than flat surgical masks.
Comfort
Be sure to find a comfortable and breathable hiqh-quality mask that you or your child will be able to wear for a long time -- the entire time you will be around people outside of your house.
Sources for Better Masks
New York Times article about sources for legitimate N95, KN95, and KF94 masks (and identifying counterfeits): https://www.nytimes.com/article/covid-masks.html
Cambridge school volunteer-run bulk mask purchase: https://cambridgemasks.org (Bulk order program is over, but this site contains helpful information and discount codes for mask purchasing.)
You can order KF94/KN95 masks directly from the following validated suppliers. Amazon.com is not recommended because counterfeit masks are common.
Key references:
Find The Right Mask: https://cambridgemasks.org/images/flyer_en.pdf
Getting the Most from your Mask: https://drive.google.com/file/d/19ALMpBfdOBm2lWV40cFzxUok_nHIAeb8/view
"Kids Mask For 12 & Under - A Primer for Parents in Under 20 Minutes": https://www.youtube.com/watch?v=A88AGnN-nwI
Mask Accessories for Better Fit
Links to example products:
"Cord locks" to adjust ear strap length for tighter face fit:
"Ear Savers" to tighten ear loops behind head, reducing ear discomfort:
Foam nose bridge pads to achieve comfortable air-tight fit around nose: (Especially useful for KF94 masks and small child faces):
Child size: https://amazon.com/gp/product/B08CZVMVXJ
Adult size: https://amazon.com/gp/product/B08HJH2TQM
Mask Braces to improve fit of surgical masks (not needed for KF94, KN95, N95):
Additional Resources / References / Sources
Mask testing research and recommendations by Aaron Collins, an aerosol researcher
"Kids Mask For 12 & Under - A Primer for Parents in Under 20 Minutes" from 2021-08-15 https://www.youtube.com/watch?v=A88AGnN-nwI
"Current Top Mask Picks & Kids Masks" from 2021-03-21 https://www.youtube.com/watch?v=WE5Uo3F2TdU
Stanford/Yale Mask study performed in Bangladesh
https://med.stanford.edu/news/all-news/2021/09/surgical-masks-covid-19.html
"There were significantly fewer COVID-19 cases in villages with surgical masks compared with the control villages. (Although there were also fewer COVID-19 cases in villages with cloth masks as compared to control villages, the difference was not statistically significant.) This aligns with lab tests showing that surgical masks have better filtration than cloth masks. However, cloth masks did reduce the overall likelihood of experiencing symptoms of respiratory illness during the study period." ... “Our study provides strong evidence that mask wearing can interrupt the transmission of SARS-CoV-2. It also suggests that filtration efficiency is important. This includes the fit of the mask as well as the materials from which it is made. A cloth mask is certainly better than nothing. But now might be a good time to consider upgrading to a surgical mask.”
Information on high-filtration masks
Choose "Resources for Public", then see "N95 Alternatives: High-Performance COVID-19 Masks" (https://www.n95decon.org/files/high-performance-masks)
https://drive.google.com/file/d/19ALMpBfdOBm2lWV40cFzxUok_nHIAeb8/view ("Getting the most from your mask.pdf" -- includes resources for purchasing high-filtration masks)
Cambridge Department of Public Health / Public Schools resources
Find The Right Mask: https://cambridgemasks.org/images/flyer_en.pdf
Bulk-ordering of masks via Cambridge Masks program on 10/8/2021: https://cambridgemasks.org
https://drive.google.com/file/d/19ALMpBfdOBm2lWV40cFzxUok_nHIAeb8/view ("Getting the most from your mask.pdf" -- includes resources for purchasing high-filtration masks)
https://p5cdn4static.sharpschool.com/UserFiles/Servers/Server_3042785/File/back_to_school/Masks_Keep_You_Healthy.pdf (Earlier version at https://www.cpsd.us/UserFiles/Servers/Server_3042785/File/back_to_school/Masks_Keep_You_Healthy.pdf)
Compiled by Martin Kemp (mdkemp at mdkemp dot net)