Skin-care packaging makes a lot of promises. Words like “anti-aging,” “firming,” and “illuminating” are all assurances you may see plastered on bottles and tubes.

And then there’s “pollution-fighting,” becoming ever more present on sunscreens, moisturizers, foundations, and more. And it’s not just marketing, say experts.

“Just like waste and industrial pollution contaminates our natural environment, our bodies and organ systems can be affected by pollutants we encounter in our day-to-day lives,” says Dr. Brendan Camp, a dermatologist with MDCS Dermatology in New York.

So how does pollution impact your complexion, and what can you really do about it when you’re in the beauty aisle? Below, dermatologists explain—and stress why it’s important to keep your guard up when you’re shopping for skin-care products.

How pollution affects your skin

Pollutants come in many forms, but those that negatively impact the skin, according to research, include ultraviolet radiation (UV), nitrogen oxide, cigarette smoke, heavy metals, arsenic, polycyclic aromatic hydrocarbons (produced when coal, crude oil, or gasoline is burned), and volatile organic compounds, which are gases emitted into the air from products or processes involving paint, varnish, cleaners, pesticides, smoking, and more.

It’s probably not surprising to learn that what’s in the air has an effect on our skin.

“Pollutants like particulate matter, heavy metals, and volatile organic compounds can generate free radicals [unstable atoms that damage cells] when they come into contact with the skin,” explains Dr. Shereene Idriss, dermatologist and founder of the skin-care line Dr. Idriss. “These free radicals cause oxidative stress, damaging skin cells, collagen, and elastin, which contributes to premature aging and a dull complexion.”

They also deplete your body’s antioxidant capacity and may cause dryness, acne, inflammation, and other skin issues, according to a recent article in the International Journal of Women’s Dermatology. “The skin’s barrier function is crucial for protecting against external aggressors and retaining moisture. Pollutants can weaken this barrier, leading to transepidermal water loss [meaning that it evaporates through the skin], dryness, and increased susceptibility to irritants and allergens,” says Idriss.

What skin-care ingredients fight the effects of pollution?

While there are no skin-care products that can “block” or “fight” pollution directly, serums and moisturizers can help your skin recover from exposure to pollutants in your environment. Specifically, Dr. Idriss says, antioxidant ingredients like vitamin C, vitamin E, niacinamide (a form of vitamin B3), green tea extract, coenzyme Q10, and ferulic acid may help your skin bounce back from the pollutants all around you.

If a product claiming to be pollution-fighting does not contain one or more of those antioxidants, there’s a pretty good chance you’re just dealing with marketing. Same goes with products that say they’re “protecting” the skin barrier.

“When shopping for anti-pollution skin care, look for ingredients that enable skin to recover and repair from external stressors,” says Dr. Camp. “Ceramides are lipids that reinforce the integrity of the skin barrier and help skin retain moisture.” He also recommends hyaluronic acid, which may improve skin hydration and vitamin C, which—you guessed it—protects the skin against free radicals.

“Antioxidants are a class of ingredients that protect skin from the effects of free oxygen radicals. Free radicals develop as a result of normal cellular metabolism [chemical reactions that occur in normal living cells] and UV exposure,” says Dr. Camp. “They are unstable oxygen molecules that negatively impact cellular structures, like DNA, lipids, and protein. In doing so, free radicals contribute to inflammation and premature aging.”

While anyone in any environment could use anti-pollution skin care, “those that live in urban or industrial locations where air pollution is more common,” says Dr. Camp, may particularly want to consider it.

If you feel overwhelmed by the prospect of adding one more step to your skin-care routine, Dr. Idriss recommends keeping it simple. “Don’t give yourself one more thing to worry about,” she says. “Simply be sure to include an antioxidant in your routine, like vitamin C, to protect against free-radical damage, and niacinamide to help strengthen your skin barrier.”

Perhaps the easiest solution is to protect your skin from UV rays. Smart sun practices such as wearing sunscreen, sunglasses, and a wide-brimmed hat (particularly during the hottest, brightest parts of the day) will do the trick—as will heeding the air-quality report in your weather app. If experts say to stay inside with your air purifier, listen.

More on skin care:

• 5 signs your skin is just as stressed out as you are

• Sunscreen myths, debunked by dermatologists 

• It's natural for skin to thin with age. Here's how dermatologists say you should care for yours

This story was originally featured on Fortune.com