So many invisible things haunt your skin like ghosts and sabotage it (er, that sounds dramatic but I just mean that they potentially cause it damage). One of the least understood—yet still really troublesome—factors? Free radicals.

The name doesn’t really indicate what they are, and not everyone has a degree in biochemistry to understand their root cause. Yet free radical damage is one of the instigators of everything from fine lines to age spots to lack of collagen, so it’s something that’s good to be familiar with.

The tough thing is that these skin enemies are almost impossible to spot…until their effects show up on your face in ways you didn’t exactly invite. To guard against them, in your own routine, there are several key things to know.

Keep reading to learn what exactly free radicals are, how they affect your skin, and—most importantly—how you can keep your complexion protected.

What *are* free radicals?

Prepare for some throwback language you probably haven’t heard since high school: Free radicals are reactive, unstable molecules with unpaired electrons, according to James Hammer, a Boston-based cosmetic chemist and president of Mix Solutions Consulting. “They can be damaging to the body, affecting cells and DNA, and ultimately contributing to aging and disease,” he explains. “They’re formed naturally in the body and through exposure to damaging factors in the environment.”

According to pros, there are a slew of different free radical types, such as nitrogen-based ones from cigarette smoke, but the most common ones that you’re exposed to regularly as an oxygen-breathing being are oxygen-based. “The oxygen atoms with the unpaired electrons move around looking for electrons to pair with, and this process of scavenging is what causes all sorts of DNA, cell, and protein damage,” says Mark Gray, MD, a New Zealand-based dermatologist and founder of Ao Skincare. “The skin’s particularly susceptible to it.”

As these important parts of the cell lose their ability to function in a normal way, they oxidize, which impacts your skin and other internal cellular pathways as well. “You may not be able to see this happening at the time in your skin, but think of an apple that’s been cut in half,” Dr. Gray says. “It’ll go brown fairly quickly. This is due to the oxidization process, and is associated with disease and the aging process.”

How pollution is a culprit

Even though free radicals may be hitting your skin without you realizing it, it’s not as though you need to stay cooped up indoors (more on how to deal later). “Environmental factors that speed up the process of aging come from things like air and water pollution, cigarette smoke, alcohol, industrial solvents, radiation, and cooking—think smoked meat and used oil,” says Dr. Gray. Over time, the effects of these things will start to show in your skin by way of less collagen and elastin, premature aging, dryness, and age spots.

Sadly, you’re not off the hook even if you don’t live in an urban environment. “Pollution’s not just found in cities,” explains Dr. Gray. “Country and rural areas get it through insecticides, fertilizers, and other chemicals used in farming and agriculture.” This is precisely why there’s such a push towards organically-grown produce—the less chemicals, the less free-radical damage (and the better your body will be for it).

Keeping your skin in check

You can put up the defense mode both topically and internally by loading up on antioxidants.

“Antioxidants in foods, supplements, and skin-care products can help to counter free radical activity,” says Hammer. After all, more research has been pointing to a direct relationship between oxidative stress (the process whereby your body can’t synthesize all the oxygen in its way so it creates free radicals) and acne—and antioxidants are able to bind an electron to these unstable free radicals to neutralize them.

As far as nutrients go, he recommends vitamins E and C along with beta carotene, and super-fruit extracts like goji berry and pomegranate.

“Your diet is a good first step [in protecting against free radicals],” echoes Dr. Gray, noting that it’s your first line of defense. “Next is to care for the outside of your body with the right skin-care products.” For this, he recommends a good cleanser to remove pollution particles, antioxidant-rich creams and serums with ingredients like green tea extract, fruit extracts, and vitamins A, B3, C, and E, and sunscreen (of course). “Zinc, in particular, is a fantastic ingredient to look for that defends against environmental stressors and harmful rays,” he says, because it creates a physical block (a shield of armor, if you will) between the outdoor stressors and your skin. Finally, never underestimate covering up, wearing a hat or simply thinking about avoiding spending a lot of time in the direct sunlight.

To protect yourself, these are the best sunscreens for your face—no chalky streaks in sight. And these are the ingredients you need to deal with *every* skin issue.