Your Ultimate Guide to Understanding and Preventing Ultraviolet Radiation: Eye and Body Health

In the simplest terms, UV radiation is invisible energy expelled by the sun. Our bodies need it to synthesize vitamin D and endorphins in the skin, and ultraviolet radiation benefits us by mediating that natural process.

However, too much UV sun exposure, where the eyes and body are exposed to high amounts over prolonged periods, can have associated risks.

The mixed good and bad effects of UV light can be confusing. So, what’s the big deal, and what sweet spot should we aim for to be able to enjoy ourselves outside, worry-free?

Arming yourself with knowledge and being able to choose and control the amounts of ultraviolet radiation you expose yourself to are key factors. This article is your guide to all things UV-related, so you can keep you and your family informed, aware, safe.

What is ultraviolet radiation?

As UV radiation is sun energy, it’s important to know where UV light sits on the electromagnetic spectrum, which helps us understand the levels of energy and wavelength of all the radiation hitting the earth. As a rule, the shorter the wavelength, the more harmful the UV radiation is.

Ultraviolet light is invisible to the eye, taking up the space between visible light and X-rays at the wavelength range of 100 to 400 nanometers (one billionth of a metre). Ultraviolet light has a shorter wavelength and is more energy-packed than visible light, making it damaging to health. Because ultraviolet radiation is composed of shorter waves, you can’t see it with your eyes, but you can feel it on your skin.

That said, not all UV radiation is created equal.

Types of UV radiation

Did you know that though shorter wavelengths are more harmful to your health, it’s also harder for them to penetrate through the skin? The good news in the fight against UV damage is that it’s very easy to protect your body against the effects of all ultraviolet radiation when experiencing sun exposure.

Before we get into how to protect ourselves, we first need to know about the three types of UV radiation:

1. UVA

With long-range wavelength radiation of 322 and 400nm, UVA rays are the least energetic of the three, which means they can penetrate deep into the skin (dermis). These are the rays that are responsible for most of the tanning effects of sun exposure and tanning beds. UVA rays contribute to prolonged skin and eye damage, ageing, and skin cancer development. UVA is not willingly absorbed by the ozone layer, so about 95 percent of it gets through.

2. UVB

UVB is short wave radiation between 280 and 320nm, which makes it capable of penetrating only a thin layer of the skin, but the culprit responsible for sunburn of the skin and eyes (yes, your eyes can get sunburnt. While more damaging, around 95 percent of this type of radiation is absorbed by the ozone, meaning just about 5 percent reaches through to affect us.

3. UVC

With the shortest wavelengths between 100 and 280nm, UVC radiation is very energetic and dangerous to life but essentially unable to penetrate the ozone layer, never reaching the earth. UVC is sometimes artificially created on earth to act as an air, water and surface disinfectant, as it kills bacteria.

Everything you need to know to stay UV safe

Many factors affect the intensity of ultraviolet radiation and how it affects you. Eye damage from sunlight happens, and it can happen quickly or over time. Below are some of your questions we’ve answered to help you protect yourself as you go about your day:

How does time of day affect sun exposure?

Find out what time the sun is closest to earth in your region and be extra cautious during those times. In Canada, that’s between 11:00 a.m. and 3:00 p.m.  

Do seasonal changes affect UV radiation? 

UV intensity is at its highest during the spring and summer months but fall and winter can still have a big effect, especially by water or with snow on the ground.

How does the ozone layer interact with UV light?

Usually thinner during the spring months due to greenhouse gases, the thickness of the ozone layer over your area has a direct impact on how much ultraviolet radiation gets through.

How do weather conditions impact UV rays?

Heavy clouds absorb some UV radiation because they’re packed with water vapour, but scattered clouds can increase its effects due to reflection. Additionally, Pressure systems affect the thickness of the ozone layer: high-pressure causes thinning while lower pressure causes thickening.

Are some surfaces conducive to heightening the strength of UV radiation?

Snow can reflect up to 85 percent of UV radiation, which means it’s coming at you from above and below, sometimes even doubling the radiation you’re experiencing. Sand, concrete, water, and any other bright surface will have similar effects.

How do altitudes impact the level of exposure to ultraviolet radiation?

If you’re a frequent flier or love to climb mountains, remember: the higher you are, the more UV radiation you’re exposed to. UV radiation increases because there’s less atmosphere for absorption.

Is the latitude of a location responsible for concentrated UV radiation?  

Similarly to the time of day, the closer you are to the sun, the more radiation you experience. Your location on the globe will have a big impact on the maximum amounts of UV radiation that can be experienced. The equator is the closest area of the earth to the sun, with the UV index capable of reaching a 12.

DID YOU KNOW: 80 percent of UV rays can penetrate clouds, mist, and fog. That means even if it’s not a sunny day outside, the UV damage of going out without sun protection is virtually the same.

UV protection: how to avoid UV rays and protect your eyes and body

Some of the most solid preventative measures against UV damage and sun exposure are tried and true easy options to incorporate into your routine:

1. Understand the UV Index

Before you head outside, we recommend checking your UV Index to make sure you’re aware of the conditions and can prepare accordingly. The UV index will indicate a UV rating from 1-11+. The higher the UV index, the greater the strength of the sun’s UV rays and the more damage it can do in a short amount of time.

The UV index considers latitude, elevation, weather, time of year and ozone layers in your region. Anything above an eight should warrant caution, and it is advisable to stay indoors or take all the safety steps you can. Remember that ultraviolet radiation is classified as a carcinogen and should be taken seriously.

2. Stay in the shade

The best protection afforded to anyone outside is having something between yourself and direct sunlight. Whether you’re enjoying a patio or working by a window, ensure you are in the shade to avoid exposure. Remember that UV rays go unnoticed on cloudy days or in cooler environments, but it doesn’t mean its damaging effects aren't reaching your eyes and skin.

3. Wear clothes that cover your arms and legs

On days with higher UV ratings, bring a light long sleeve to cover yourself with, or opt for long, breezy pants in breathable fabrics. Just as sunglasses are used to minimize sun damage to eyes, the extra layer of clothing (especially in light colours) will keep you shaded and guard you against as much as 80 percent of the radiation.

4. Wear a wide brim hat

Your head, face, eyelids and neck have some of the thinnest skin on your body and are considered the most delicate areas. That also means that they’re the most susceptible to sun exposure. A big hat is a perfect accessory that can protect all three.

5. Don’t forget your sunglasses

Your eyes can sunburn! Eye damage from sunlight happens frequently. If your eyes feel irritated, red, and you have vision problems after a day in the sun, you may have, ultraviolet keratitis, aka photokeratitis, or more simply, what people call eye sunburn. Temporary and permanent damage can result without proper protection, so keeping your eyes covered with a pair of UV protection sunglasses is always recommended.

6. Wear broad spectrum sunscreen with SPF 30 or higher

Aim for a sunscreen that is considered broad range. Up until recently, UVA damage wasn’t well understood, so manufacturers only guarded against UVB rays. Now, UVA and UVB are included in what is considered “broad range protection” that’s the sunscreen you want. Be sure to cover as much skin as you can, including your eyelids.

The SPF number is a guide created to let you know how long it will take the sun to damage your skin. So, SPF 30 means it would take 30 times as long as if you weren’t wearing sunscreen protection, and so on. SPF 30 is considered good, but many doctors recommend 50 or higher for optimal protection, especially during prolonged exposure to the sun. Remember: reapply every 2 hours!

7. Avoid indoor tanning

More than 419,000 cases of skin cancer a year are reported linked to indoor tanning beds. For the eyes, tanning has similar results. Beyond ocular cancers, diseases linked to UV exposure include glaucoma, cataracts, diabetic retinopathy and AMD.

8. Be aware of when you’re most photosensitive

Some medications, skin products and health conditions can make you even more sensitive to ultraviolet radiation. Whether that’s burning faster or developing an allergic reaction after sun exposure, be aware of how medications and illnesses may be affecting your body, and try to avoid sun exposure while your health is jeopardized.

TIP: Sun protective clothing exists! Clothes with SPF 50 are something you can now find in stores and online. The fabric can block over 98 percent of UV radiation.  

For optimal eye health when spending time outdoors, it’s best to discuss your needs and worries with your eye doctor. Catching potential damage early and educating yourself on risks and behaviours to avoid is the best step toward a health plan that will help your vision.

Book an eye exam with your local FYidoctors clinic today.