Do Carbon Filters in Face Masks Offer More Protection Against Coronavirus?

Cloth face masks can help slow the spread of coronavirus. But do they need filters, too?
Cloth face masks can help slow the spread of coronavirus. But do they need filters, too?
JohnnyGrieg/iStock via Getty Images

Through the winter, spring, and summer of a global pandemic, many people have gotten used to the idea of wearing a cloth face covering to reduce the spread of the coronavirus, the highly infectious virus looking to find as many human hosts as possible. Masks both inhibit the distribution and inhalation of respiratory droplets, which can carry the virus.

Recently, a number of homemade and mass-produced cloth face masks for sale online have boasted of having a carbon or other kind of filter in place that might improve the efficacy of the mask, warding off even more viral particles than the mask alone. Can this additional filtration really help?

According to health experts, the answer is yes—but you should exercise caution in what type of filter you choose.

Filters are typically sandwiched between two layers of cotton. Alternately, a mask provider might offer a mask with a pocket for a filter of your choosing. Some filters claim to be HEPA-certified, a standard for air filtration, or made with carbon, which may increase the potential for particulates to stick to the material, blocking it from entering or exiting the mask. But while these filters are used in air filtration devices, their effectiveness has yet to be evaluated when worn on the face.

“Carbon and charcoal are meant to filter contaminants from water,” May Chu, Ph.D., a clinical professor of epidemiology at the Colorado School of Public Health Anschutz Medical Center, tells Mental Floss. “We don’t know if breathing in charcoal fragments or particles is good for your lungs.”

The same holds true for using vacuum cleaner bags or coffee filters. Some, Chu says, are made with silica fibers, or glass. That’s not anything you want in your lungs. “These are not designed for breathing,” Chu says.

According to Chu, the most important feature of a mask is that it hits the “sweet spot” of locking in particles while maintaining comfort and breathability. If a mask is very thick, you’re not likely to inhale droplets through it, but you might have trouble with air passing through it and would likely wind up inhaling through the open sides, where there’s no barrier.

Cotton is the preferred mask material. A tight weave cotton allows for air flow and tends to trap particles better than synthetic materials, which have a smoother structure. Cotton also tends to work best with one or more layers depending on whether you can see light shine through it. If you can, it’s too thin.

Because cotton isn’t intrinsically designed to protect against particles, there is value in adding a filter. But like the mask itself, it needs to be made of a safe material that’s comfortable to wear. Chu recommends polypropylene, a material that can be purchased under the brand name Oly-Fun from Walmart and other retailers and is also sold under the name Spunbond.

Polypropylene is sold under the brand name Oly-Fun. Walmart

What’s so special about polypropylene? “It’s the same material used in N95 masks,” Chu says. The N95 mask is used by medical professionals and filters up to 95 percent of airborne particles. But Chu cautions that consumers need to be aware that there are differences between store-bought polypropylene and the kind used in a medical-grade N95.

“The quality of the N95 polypropylene is calibrated and designed for a particular level of filtration that has a standard,” she says. “It’s more expensive and tooled more precisely.” Two layers of Spunbond polypropylene can approach—though not duplicate—the protective qualities of a single layer of the medical quality mask filters.

Polypropylene is effective because it can hold a static charge that repels particles. While an N95 mask is made to hold that charge for the life of the mask, you can generate a charge with a homemade filter by ironing the polypropylene or rubbing it with a plastic glove for 20 seconds. The charge will last for roughly 12 hours or until it’s washed, Chu says.

If polypropylene isn’t available, there’s an alternative that virtually anyone can use. Simply stuff four sheets of Kleenex (or two sheets folded in half) into the pocket of the mask. “The Kleenex gives you good efficiency in blocking particles and breathability,” Chu says.

No matter which filter you use, it’s important to remember that once a mask or filter gets wet, it loses its ability to hold a charge (for polypropylene) or block particles (facial tissue). The filter needs to dry or be switched out in order to maintain its effectiveness.

Obviously, medical professionals opt for an N95 when they’re available. But what does Chu do when it’s time to wear a cloth mask? “I wear a mask that’s locally made,” Chu says. “It’s two layers of polypropylene pocketed by cotton in the front and back.”

Coupled with social distancing and hand washing, a breathable mask with a safe filter can slow the spread of the virus, reducing infectious droplets that come out of a person’s mouth. “That’s why masks are good,” Chu says. “That’s what we know works.”

10 Rad Gifts for Hikers

Greg Rosenke/Unsplash
Greg Rosenke/Unsplash

The popularity of bird-watching, camping, and hiking has skyrocketed this year. Whether your gift recipients are weekend warriors or seasoned dirtbags, they'll appreciate these tools and gear for getting most out of their hiking experience.

1. Stanley Nesting Two-Cup Cookset; $14


Stanley’s compact and lightweight cookset includes a 20-ounce stainless steel pot with a locking handle, a vented lid, and two insulated 10-ounce tumblers. It’s the perfect size for brewing hot coffee, rehydrating soup, or boiling water while out on the trail with a buddy. And as some hardcore backpackers note in their Amazon reviews, your favorite hiker can take the tumblers out and stuff the pot with a camp stove, matches, and other necessities to make good use of space in their pack.

Buy it: Amazon

2. Osprey Sirrus and Stratos 24-Liter Hiking Packs; $140


Osprey’s packs are designed with trail-tested details to maximize comfort and ease of use. The Sirrus pack (pictured) is sized for women, while the Stratos fits men’s proportions. Both include an internal sleeve for a hydration reservoir, exterior mesh and hipbelt pockets, an attachment for carrying trekking poles, and a built-in rain cover.

Buy them: Amazon, Amazon

3. Yeti Rambler 18-Ounce Bottle; $48


Nothing beats ice-cold water after a summer hike or a sip of hot tea during a winter walk. The Yeti Rambler can serve up both: Beverages can stay hot or cold for hours thanks to its insulated construction, and its steel body (in a variety of colors) is basically indestructible. It will add weight to your hiker's pack, though—for a lighter-weight, non-insulated option, the tried-and-true Camelbak Chute water bottle is incredibly sturdy and leakproof.

Buy it: Amazon

4. Mappinners Greatest 100 Hikes of the National Parks Scratch-Off Poster; $30


The perfect gift for park baggers in your life (or yourself), this 16-inch-by-20-inch poster features epic hikes like Angel’s Landing in Zion National Park and Half Dome in Yosemite National Park. Once the hike is complete, you can scratch off the gold foil to reveal an illustration of the park.

Buy it: Amazon

5. National Geographic Adventure Edition Road Atlas; $19


Hikers can use this brand-new, updated road atlas to plan their next adventure. In addition to comprehensive maps of all 50 states, Puerto Rico, Canada, and Mexico, they'll get National Geographic’s top 100 outdoor destinations, useful details about the most popular national parks, and points on the maps noting off-the-beaten-path places to explore.  

Buy it: Amazon

6. Adventure Medical Kits Hiker First-Aid Kit; $25


This handy 67-piece kit is stuffed with all the things you hope your hiker will never need in the wilderness. Not only does it contain supplies for pain, cuts and scrapes, burns, and blisters (every hiker’s nemesis!), the items are organized clearly in the bag to make it easy to find tweezers or an alcohol wipe in an emergency.

Buy it: Amazon

7. Hiker Hunger Ultralight Trekking Poles; $70


Trekking poles will help increase your hiker's balance and stability and reduce strain on their lower body by distributing it to their arms and shoulders. This pair is made of carbon fiber, a super-strong and lightweight material. From the sweat-absorbing cork handles to the selection of pole tips for different terrain, these poles answer every need on the trail. 

Buy it: Amazon

8. Leatherman Signal Camping Multitool; $120


What can’t this multitool do? This gadget contains 19 hiking-friendly tools in a 4.5-inch package, including pliers, screwdrivers, bottle opener, saw, knife, hammer, wire cutter, and even an emergency whistle.

Buy it: Amazon

9. RAVPower Power Bank; $24


Don’t let your hiker get caught off the grid with a dead phone. They can charge RAVPower’s compact power bank before they head out on the trail, and then use it to quickly juice up a phone or tablet when the batteries get low. Its 3-inch-by-5-inch profile won’t take up much room in a pack or purse.

Buy it: Amazon

10. Pack of Four Indestructible Field Books; $14


Neither rain, nor snow, nor hail will be a match for these waterproof, tearproof 3.5-inch-by-5.5-inch notebooks. Your hiker can stick one in their pocket along with a regular pen or pencil to record details of their hike or brainstorm their next viral Tweet.

Buy it: Amazon

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Can the Electoral College Reverse the Results of an Election?

Tumisu, Pixabay // Public Domain
Tumisu, Pixabay // Public Domain

Every four years, people talk about the oddness of the Electoral College. And just like 2000's popular vote/Electoral College mismatch, after the 2016 election, some citizens attempted to flip electors from Donald Trump to either Hillary Clinton or a third candidate (if enough electors go to the third candidate, the House would then have to choose from among the top three).

Which leads to the question: Can the Electoral College actually change the results of the election? It’s an awkwardly worded question for a very specific reason, and the answer is no. But for the question people think that they’re asking—could the Electoral College reverse the results of the election?—the answer is yes, although it’s profoundly unlikely.

The reason it’s an oddly worded question is that the November election is not a vote for president. The vote is for a set of electors who will then go and vote for the president in December. Therefore, the electors cannot change the results of the election since they’re the ones being elected. In one of the Federalist Papers, Alexander Hamilton explained the reasoning for forgoing direct democracy, as well as why they avoided letting politicians make the decision. Largely, the problem was that neither the public nor the politicians could be trusted. Hamilton wrote:

“The Executive should be independent for his continuance in office on all but the people themselves. He might otherwise be tempted to sacrifice his duty to his complaisance for those whose favor was necessary to the duration of his official consequence. This advantage will also be secured, by making his re-election to depend on a special body of representatives, deputed by the society for the single purpose of making the important choice.”

There were other issues the Founding Fathers were trying to avoid as well, such as the risk of a smorgasbord of regional candidates. As historian Jack Rakove told Stanford News in 2012, “it would become truly difficult to produce a popular majority with a field of favorite sons.”

More controversially, the Founding Fathers faced the issue of slavery. Because enslaved people couldn’t vote, a direct popular vote would weaken the power of the South. Thanks to the three-fifths compromise, however, the slave states had greater power under an electoral system than under a direct voting system, because enslaved people couldn’t vote but did count for the number of representatives. And more representatives meant more electors (the number of electors equals the state’s number of representatives plus the number of senators). As James Madison said in 1787:

“There was one difficulty however of a serious nature attending an immediate choice by the people. The right of suffrage was much more diffusive in the Northern than the Southern States; and the latter could have no influence in the election on the score of the Negroes. The substitution of electors obviated this difficulty and seemed on the whole to be liable to fewest objections.”

But objections to the elector’s powers appeared as soon as races got competitive. In 1796, Pennsylvanian Samuel Miles became the first known faithless elector when, despite being chosen as a Federalist, he voted for opposition candidate Thomas Jefferson. In a letter to the Gazette of the United States, a disgruntled Pennsylvania voter asked, “What, do I choose Samuel Miles to determine for me whether John Adams or Thomas Jefferson shall be President? No! I choose him to act, not to think.”


As we have written about before, in about half the states plus Washington, D.C., electors are required to vote for their state’s popular vote winner—some states to the point that any attempt to defy this would forfeit the elector’s position. They’re extreme, but in the controversial 1952 Ray v. Blair case, the Supreme Court ruled that requiring pledges from electors to vote for a particular candidate was constitutional. But the question that remains unanswered is whether any punishment for breaking those pledges is constitutional. It’s never mattered, but would quickly become a critical issue if electors defected en masse.

Regarding the 2016 election, others say that because Hillary Clinton had already conceded, this strategy wouldn’t have worked. But there’s no requirement that an elector vote for a viable candidate. In 1976, one of the electors voted for Ronald Reagan, who hadn’t even won his party’s primary. In 1956, another elector voted for a local circuit court judge rather than Adlai Stevenson.

A stronger issue standing in the way is how electors are chosen. Generally, in spring and summer, each state’s political parties nominate a slate of electors from a list of party faithful. Any attempt to get defections would require electors to go against a party that chose them specifically for their loyalty.

The Ray v. Blair decision gave one of the most famous dissents in Supreme Court history, where Justice Jackson wrote, “No one faithful to our history can deny that the plan originally contemplated, what is implicit in its text, that electors would be free agents, to exercise an independent and nonpartisan judgment as to the men best qualified for the Nation's highest offices.” While it would be considered highly irregular and is highly unlikely, the possibility is there. And will remain there until January 6, 2021, when the votes are officially counted before a joint session of Congress.

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