Grace Cary / Getty images
As new and more easily transmissible COVID-19 strains continue to spread, wearing a mask with a filter can provide you with extra security. "A face mask filter adds another layer of protection to an ordinary face mask," says Dr. Curtis White, PhD., chief technology officer of ViaClean Technologies. "Much like a filter used in an air conditioning or HVAC system, a face mask filter's purpose is to trap microscopic particles that may ordinarily pass through a mask made of cotton, linen, or other materials."
While wearing a standard face mask can protect you from larger droplets, Dr. Ankit Garg, medical director at MVP Health Care says face mask filters are designed to protect you from the airborne transmission of the virus. "Airborne transmission is from viruses lingering around in particles smaller than droplets, especially in poorly ventilated spaces like restaurants, public transportation, et cetera," he explains. "Face mask filters may decrease the risk of transmission if you are planning to be in a poorly ventilated public space."
Interested in learning more about face mask filters? From the best face mask filter materials to DIY styles you can make at home and more, doctors share their insight ahead.
For PM 2.5 Filter: Cherislpy PM2.5 Face Mask Filter
For Polypropylene Filter: Airflow Products Polypropylene Face Mask Filter Insert
For HEPA Filter: The Mask and Filter Shop HEPA Filter Face Mask Insert
For Cloth-Mask Filter: Rendall Co. "Ace" Mask
For N95 or KN95: Public Goods Face Mask
PM 2.5 Filters
According Dr. Evelyn Darius, a physician with virtual health platform PlushCare, PM 2.5 filters are composed of nanofibers designed to filter particles down to 2.5 microns in size. "Particulate matter, PM, refers to any substance floating in the air, from dust to pollen to viruses," she explains. "Most viruses are 0.004 to 0.1 microns in size, which is about 100 times smaller than bacteria, so it is best to choose a filter with a PM 2.5 rating, which should filter out most viruses, including coronavirus."
Shop Now: Cherislpy PM2.5 Face Mask Filters, $5.60 for 10, amazon.com.
Since increased humidity can decrease the efficiency of a filter, Dr. Darius says adding a polypropylene layer to a mask can provide extra protection against airborne viruses. "Polypropylene is a polymer that is characteristically non-absorbent and hydrophobic," she explains. "The nature of the filter ensures that it does not become humid, therefore, maintaining a high filtration efficiency."
To better protect yourself (and others) from the various strains of coronavirus, Dr. Daniel Berliner, primary care doctor with virtual health platform PlushCare and a former flight surgeon in the U.S. Army, recommends adding a polypropylene filter to a layered cloth mask. "The addition of an industry-grade spun-bonded polypropylene layer to an existing two-layer cloth mask will provide effective small particle filtering," he says.
Shop Now: Airflow Products Polypropylene Face Mask Filter Insert, $15.99 for 20, amazon.com.
Commonly used in vacuums and air purifiers, HEPA (High-Efficiency Particulate Air) filters can trap everything from pet dander and dust mites to bacteria, viruses, and mold, which is why Dr. Garg says certain ones can be used as face mask filters. "HEPA filters are highly efficient in absorbing particulates and can effectively filter out the smaller ones," he explains. Just be sure to look for HEPA face mask filter inserts that are labeled as fiberglass-free, because the small fibers of glass in non-fiberglass-free HEPA filters can be inhaled and cause serious lung irritation.
Shop Now: The Mask and Filter Shop HEPA Filter Face Mask Insert, $23.95 for four, amazon.com.
DIY Cloth Filters
According to Dr. Darius, you can fashion your own mask at home with the right types of fabric. "The American Chemical Society says homemade masks with both mechanical and electrostatic filtration can be highly effective in filtering out particles—as long as they fit properly," she explains. "The effect can be achieved by combining two commonly used cloths, such as silk and cotton-flannel, which have been shown to increase the efficiency of a mask up to eighty percent for particles less than 300 nanometers."
Shop Now: Rendall Co. "Ace" Mask, $15.99 each, rendallco.com.
Ultimately, wearing a mask with a built-in filter might be your best option. Masks with a filter, such as an N95, offer the most protection due to the added layer of protection that the filter provides, our experts explain. So, while any mask is better than nothing, wearing one with a filter provides extra backup protection. But since N95 masks are hard to find and should continue to be reserved for healthcare professionals, the KN95 mask is manufactured to comparable standards.
Shop Now: Public Goods Face Masks, $44 for 10, publicgoods.com.