#How to wash a face mask properly — and when to throw it away

Whether it be a bandanna, scarf or gas mask, we now know that any mouth and nose covering is better than none at all when it comes to coronavirus prevention.

So, keeping our health in mind, Dr. Rita Linkner, an NYC-based dermatologist, is now talking to her patients about more than how to “treat your skin properly underneath the mask.”

“With coronavirus, our new existence for the foreseeable future will involve wearing masks,” she tells The Post. “It’s important to know how to take care of your mask,” which, in turn, will help keep rashes and other skin problems at bay, she says.

The type of cloth used for washable face masks is key.

“It’s important to know that the material … should be made out of non-synthetic, cotton fabric,” Linkner says.

That’s because studies have shown that cotton is both trusted to filter many potentially harmful particles, while also being breathable and gentle on the most sensitive skin.

Soap or sanitizer?

Linkner doesn’t think bleach or other disinfectants are necessary for cleaning masks, especially since they’re worn on your face. Just as a safe and gentle soap is the most effective tool against COVID-19 for your hands, it’s also your first line of defense in the laundry.

Soap molecules have a hydrophilic and hydrophobic end: The former side attracts water and repels fat, while the latter end attracts oil and repels water. Meanwhile, COVID-19 cells are enveloped in a lipid layer — a fat, in other words. So, when the hydrophobic tail of a soap molecule attempts to evade water during washing, it will actually wedge itself into the lipid layer that surrounds the coronavirus and, essentially, rip the pathogen to shreds.

Hand-washing your cloth mask

Cloth masks have the advantage of being both hand- and machine-washable, according to Linkner.

“The best way to … clean your cloth masks is to clean it like we would our bra and underwear,” she says, with a gentle soap that won’t irritate sensitive facial skin. She recommends The Laundress line of products, which are eco-friendly and, in some cases, nontoxic.

Studies show that water temperature doesn’t make a difference either, so don’t burn your hands in scalding water for the sake of sanitizing.

Machine-washing your cloth mask

For those who don’t hand-wash their undergarments, Linkner says the washing machine works just as well.

“Throw [the face mask] in your lingerie bag … on the delicate cycle on cold water and let it wash and then let it air dry,” she says. While 100% cotton could be tumble-dried, blended fabrics won’t tolerate the high heat for too many washes, so be sure to read about your particular mask’s fabric-care instructions.

Removing odor from your mask

For a midday mask refresh, Linkner also suggests a nontoxic laundry spray to help trap odors that collect in cloth fibers throughout the day — thanks mostly to your stinky breath.

“We all notice we smell our own breath and that the inside of the mask is something that needs to be refreshed,” says Linkner, who recommends The Laundress’ Fabric Fresh spray — a nontoxic deodorizer made of just water, essential oils, fragrance and alcohol — for a quick-drying effect.

Dealing with ‘maskne’

That’s mask acne — get it?

“We’ve been seeing a lot of what we call perioral dermatitis, which is as if acne and rosacea had a baby,” says Linkner. “It gives you this red, bumpy, rashy skin in the smile lines on the lower third of the face.”

Regularly washing your mask should help prevent clogged pores, but adopting the right face-cleansing routine can help fortify your skin’s defenses against the “new environment” on your face.

“Make sure you are using an exfoliative, non-oil-based cleanser, and then a glycerine-based moisturizer,” says Linkner, adding to wait a good 15 minutes before donning a mask to allow those ingredients to seep deep into your skin.

What about paper masks?

That’s simple, according to Linkner: Toss them when you’re done — since they can’t be cleaned — but be mindful if you intend to wear a mask for more than a few hours.

Going out for the day? You might want to bring two.

Says Linkner, “Do your best to dispose of them when you notice they are [collecting] debris, and it looks like it’s time to get a new one.”