What’s The Difference Between UVA And UVB Rays?

by Gio
difference between uva and UVB rays

Can you believe that for decades sunscreen protected you only from UVB rays?

No one gave a crap about UVA rays. They don’t cause sunburns, so you can’t see the damage they do as quickly. *sighs*

But don’t think for a moment that makes them less dangerous. Turns out, UVA rays are worse than UVB rays in more ways than one…

Yep, not all UV rays are created equal. Here are the differences between UVA and UVB rays and why your sunscreen should protect you from both:

What Is UV Radiation?

Ultraviolet (UV) radiation is a form of electromagnetic radiation that comes from the sun. One that we don’t see, until it’s too late.

UV radiation is totally invisible to the human eye. Only some small insects, like bumblebees, can see it. It’s a bit like dogs who can hear whistle sounds that are out of our human range.

Not all UV radiation is created equal, either. There are three (yes, three!) types:

  • UVA rays: Long wave ultraviolet radiation that’s mainly responsible for premature aging.
  • UVB rays: Short wave ultraviolet radiation that’s mainly responsible for sun burns.
  • UVC rays: You’ve never heard of them because the ozone layers absorbs them before they can reach the earth. Phew!

P.S. All types of radiation that hit the earth (and us!) can cause cancer. That’s why you always need sun protection from both.

How effective is your sunscreen? Sign up to the newsletter below to receive the “Sunscreen Audit” Worksheet and find out if your sunscreen is really up to the job:

All You Need To Know About UVA Rays

UVA rays are the sneakiest type of UV radiation. They’re weaker than UVB rays, yet far more damaging. Here’s why:

  1. They penetrate deeper into the skin: They’re long wave UV rays that can reach the deeper layers of your skin, where the cells that make collagen and elastin are. If that happens, they start destroying everything they find on their path.
  2. They’re always present (during the day): UVA rays make up a whopping 95% of UV radiation that reaches the earth. They’re present every single day, from the second the sun comes up to the second it goes down.
  3. They get through everything: They easily penetrate the darkest of clouds and shiny windows and even get reflected on snow. It doesn’t matter if you’re in the middle of the desert, in a chaotic city or on top of a snow-covered mountain. Those pesky UVA rays will get you EVERYWHERE (including your own home, if you sit near the windows) until the sun sets!
  4. They inflict invisible, continuous, and severe damage: Because they’re present all the time and can get through everything, they have more opportunities to touch your skin and damage it. To add insult to injury, there’s no tell-tale sign – like the redness that accompanies a sunburn – to let you know your skin is being damaged.
  5. They cause cancer and premature aging: UVA rays generate an endless stream of free radicals, the nasty buggers that give you wrinkles. They also reduce elastin, the protein that keeps your skin elastic and bouncy (that’s why tanners get deeper wrinkles, by the way). Like that weren’t bad enough already, they also cause abnormal cell production. Translation: they can lead to cancer.
  6. Their damage shows up after years: Unlike a sunburn that shows up straight away, it takes years (decades even) before UVA damage shows up on your skin in the form of wrinkles, sun spots, and worse.

Related: Should You Wear Sunscreen While You’re Driving?

All You Need To Know About UVB Rays

UVB rays aren’t as sneaky as UVA rays, but that doesn’t mean you should underestimate them. They’re very dangerous, too. Here’s why:

  1. They reach the superficial layers of skin: UVB rays can’t reach as deep as UVA rays, but they do reach, burn, and damage the superficial layers of skin.
  2. They’re stronger during peak hours: UVB rays emit medium wave ultraviolet radiation, so only about 5% reaches our planet. The rest is absorbed by the clouds and ozone layer (which we humans are stupidly destroying). UVB rays are stronger between 10 a.m and 4 p.m. – that’s why your mom told you to stay out of the sun during those hours.
  3. They can’t penetrate clouds and windows: If you’re inside, you’re safe from them (but you still need sunscreen to protect yourself from UVA rays).
  4. They’re stronger than UVA rays: They’re only 5%, but they burn your skin more than UVA rays.
  5. They cause cancer and sunburns: UVB ray can literally burn your skin. As soon as you see your face turning red, you know UVB rays have got you. Plus, like UVA rays, UVB rays can cause abnormal cell mutation and give you cancer.
  6. Their damage shows up straight away… or years later: It depends on what kind of damage you’re talking about. Sunburns show up on the same day. Cancer may take years to develop. Five serious sunburns, for example, may increase the risk of developing skin cancer by 80%!

Related: A Tan Isn’t Worth Dying For

The Bottom Line

These days, (almost) all sunscreens give you both UVA and UVB coverage. But, it’s still possible to find a dud that slacks on UVA protection. Make sure to leave it on the shelf!



Trisha June 29, 2010 - 9:30 pm

You’re so smart. 😉

beautifulwithbrains June 30, 2010 - 6:41 am

You’re too kind, Trisha, thanks.

Nikki June 30, 2010 - 12:48 am

Thanks for sharing this information, I remember going on a seminar about UVB and UVA and its really informative to know! thanks for the reminder!

beautifulwithbrains June 30, 2010 - 6:42 am

Nikki, you’re welcome. That seminar must have been very interesting. 🙂

Tammy June 30, 2010 - 12:53 am

Very informative! I use a zinc oxide and titanium oxide based sunscreen because they are the most stable and long lasting (on me, at least). It feels heavier, but it works better for me. What do you use?

beautifulwithbrains June 30, 2010 - 6:49 am

Tammy, I prefer to use sunscreens that contain Zinc Oxide and Titanium Dioxide as these ingredient offer protection from both UVA and UVB rays and are less likely to cause negative reactions than chemical filters. I may sometimes switch and try something with Mexoryl if it’s a product that particularly interests me but usually I stick with Zinc Oxide and Titanium Dioxide. Sure, they may feel a bit heavier and sometimes leave a white cast, but I think that’s a very small price to pay for the good protection they offer. 🙂

Celina Lee June 30, 2010 - 2:12 am

This is a great post, it clearly lays everything out, no confusion at all 🙂

beautifulwithbrains June 30, 2010 - 7:05 am

Celina Lee, thanks. I’m glad you find this helpful. 🙂

Dee June 30, 2010 - 2:25 am

Thanks for this Gio. I had no idea there were UVC rays.

beautifulwithbrains June 30, 2010 - 7:06 am

Dee, you’re welcome. I only recently found out about UVC rays too but I’m glad we don’t have to worry about them as they never reach the earth. 🙂

Dao June 30, 2010 - 3:14 am

I have this trick: A is for aging, B is for burn 🙂 That’s how I differentiate UVA and UVB. This year, the weather is so brutal that I need a back up for my sunscreen. It is a mineral finishing powder from EDM that has both zinc oxide and titanium dioxide. I love it!

beautifulwithbrains June 30, 2010 - 1:11 pm

Dao, that’s a great and simple way to remember the difference between UVA and UVB rays. 🙂 That sounds like a good powder. The weather is very hot here too so it’s nice to retouch makeup with a finishing powder with SPF for some added protection. 🙂

louise October 2, 2012 - 3:00 pm

Hi there – my website will be live in a weeks time..
I am setting up a skincare business and will be raising skin cancer awareness too. The UVA UVA diagram you have is brilliant. Could I please ask your permission to use this?
I look forward to hearing from you.
Best Regards,

beautifulwithbrains October 2, 2012 - 8:43 pm

Louise, hi. I think it’s great that you wanna raise skin cancer awereness and I wish you all the best with your skincare business.

The diagram isn’t mine, but it’s from the Make Me Heal website, so you should ask them. You can find the link to the site at the end of the post.

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