Why Do We Tan?

iStock / bymuratdeniz
iStock / bymuratdeniz

Sit out in the sun too long and ultraviolet radiation from sunlight penetrates your skin and cells, damaging their RNA and DNA. This is bad news, as DNA provides our bodies with all the genetic instructions they need to develop, survive and go about their business, and this kind of DNA damage can lead to skin cancer. To protect you from this, your body helpfully tans, darkening the the skin with a pigment called melanin that reduces UV penetration into cells.

UV radiation stimulates the darkening of existing melanin and spurs increased melanogenesis, the production of new melanin. Cells called melanocytes generate the pigment and push it out of the cell, where it darkens the skin and absorbs and transforms absorbed UV energy into heat.

Melanogenesis results in a delayed tan that only becomes visible several hours after UV exposure and lasts longer than the tanning caused by darkening of existing melanin. Over time, a tan fades as darkened skin layers are pushed upward by new cells with less melanin, and are eventually scaled off.

Why do we get sunburn?

While we might say someone with sunburn was out “baking” too long or got “fried,” sunburns are different from the burn one might get from, say, touching a hot stove. That’s a thermal burn caused by the heat of the stove. While the sun does give off heat, a sunburn is caused by ultraviolet-B radiation.

When someone’s exposure to UV radiation exceeds their body’s ability to protect the skin with tanning, the radiation  causes damage to DNA, like we talked about above. This prompts the body to try and fix things. Bloodflow to the capillary bed of the dermis (the second outermost layer of skin) increases so cells can repair the damage, which results in warmth and redness of the skin. Inflammatory immune cells also flock to the damaged tissue, causing us to perceive pain and, hopefully, consider staying out of the sun for a while. Eventually, the damaged skin cells die, and the burned skin starts to peel.

6 Protective Mask Bundles You Can Get On Sale

pinkomelet/iStock via Getty Images Plus
pinkomelet/iStock via Getty Images Plus

Daily life has changed immeasurably since the onset of COVID-19, and one of the ways people have had to adjust is by wearing protective masks out in public places, including in parks and supermarkets. These are an essential part of fighting the spread of the virus, and there are plenty of options for you depending on what you need, whether your situation calls for disposable masks to run quick errands or the more long-lasting KN95 model if you're going to work. Check out some options you can pick up on sale right now.

1. Cotton Face Masks; $20 for 4

Protective Masks with Patterns.
Triple7Deals

This four-pack of washable cotton face masks comes in tie-dye, kids patterns, and even a series of mustache patterns, so you can do your part to mask germs without also covering your personality.

Buy it: $20 for four (50 percent off)

2. CE- and FDA-Approved KN95 Mask; $50 for 10

A woman putting on a protective mask.
BetaFresh

You’ve likely heard about the N95 face mask and its important role in keeping frontline workers safe. Now, you can get a similar model for yourself. The KN95 has a dual particle layer, which can protect you from 99 percent of particles in the air and those around you from 70 percent of the particles you exhale. Nose clips and ear straps provide security and comfort, giving you some much-needed peace of mind.

Buy it: $50 for 10 (50 percent off)

3. Three-Ply Masks; $13 for 10

Woman wearing a three-ply protective mask.
XtremeTime

These three-ply, non-medical, non-woven face masks provide a moisture-proof layer against your face with strong filtering to keep you and everyone around you safe. The middle layer filters non-oily particles in the air and the outer layer works to block visible objects, like droplets.

Buy it: $13 for 10 (50 percent off)

4. Disposable masks; $44 for 50

A batch of disposable masks.
Odash, Inc.

If the thought of reusing the same mask from one outing to the next makes you feel uneasy, there’s a disposable option that doesn’t compromise quality; in fact, it uses the same three-layered and non-woven protection as other masks to keep you safe from airborne particles. Each mask in this pack of 50 can be worn safely for up to 10 hours. Once you're done, safely dispose of it and start your next outing with a new one.

Buy it: $44 for 50 (41 percent off)

5. Polyester Masks; $22 for 5

Polyester protective masks.
Triple7Deals

These masks are a blend of 95 percent polyester and 5 percent spandex, and they work to block particles from spreading in the air. And because they're easily compressed, they can travel with you in your bag or pocket, whether you're going to work or out to the store.

Buy it: $22 for five (56 percent off)

6. Mask Protector Cases; $15 for 3

Protective mask case.
Triple7Deals

You're going to need to have a stash of masks on hand for the foreseeable future, so it's a good idea to protect the ones you’ve got. This face mask protector case is waterproof and dust-proof to preserve your mask as long as possible.

Buy it: $15 for three (50 percent off)

At Mental Floss, we only write about the products we love and want to share with our readers, so all products are chosen independently by our editors. Mental Floss has affiliate relationships with certain retailers and may receive a percentage of any sale made from the links on this page. Prices and availability are accurate as of the time of publication.

Tear Gas vs. Pepper Spray: What’s the Difference?

This is probably pepper spray.
This is probably pepper spray.
Siberian Photographer/iStock via Getty Images

Pepper spray and tear gas are both non-lethal irritants that cause extreme burning of the eyes, nose, and throat—but there are a few key differences between the two substances.

For one, they’re created from different chemicals. According to biohazard remediation company Aftermath, the active ingredient in pepper spray is oleoresin capsicum, which comes from the compound that makes hot peppers so hot: capsaicin. If you’ve ever accidentally rubbed your eyes after chopping a chili pepper, you’ve gotten a very tiny taste of what it’s like to be sprayed with pepper spray. Tear gas, on the other hand, contains 0-Chlorobenzylidenemalononitrile (CS), 2-chlorobenzalmalononitrile (CN), or a similar artificial chemical. At room temperature, both of those chemicals are powdery solids, not gases—they’re mixed with liquids or gases so they can be dispersed in the air.

Delivery methods differ, too. Pepper spray often comes in an aerosol can, which shoots it in a stream, a mist, or some other relatively direct path (though it’s also available as a gel or foam). As the Berkeley Science Review explains, tear gas is mainly dispersed with a grenade, which releases the substance over a wide area when it explodes. Since the grenades can cover so much ground, law enforcement officers are more likely to use tear gas to try to break up a crowd, and civilians are more likely to carry pepper spray as a personal safety measure.

The immediate effects of the two substances are similar—burning sensation in mucous membranes, rise in blood pressure, difficulty breathing, runny nose, etc.—but tear gas can also cause nausea and vomiting in higher concentrations.

For more on tear gas, including what to do if you’re exposed to it, head here.

[h/t Aftermath]