Understanding UV rays and sun protection

For the most part, we love basking in the sun on beautiful summer days. As well as being enjoyable, reasonable sun exposure with sufficient protection offers several benefits, for example by activating vitamin D production. Nevertheless, overexposure and poor protection can lead to premature aging of the skin or even skin cancer. To avoid these serious problems, let’s take a closer look (figuratively speaking!) at these notorious UV rays in order to understand them better and learn how to protect our skin from the sun.

What are UV rays?

The sun emits several kinds of electromagnetic waves: infrared, visible spectrum, and ultraviolet. The shorter the wave, the greater its energy—and the more harm it can cause.

Ultraviolet (UV) rays are responsible for sunburns and other discomforts caused by the sun. There are three different kinds of UV rays:

UVA: Ultraviolet A rays penetrate the epidermis more deeply and accelerate skin aging.
UVB: Ultraviolet B rays consist of intermediate energy waves that penetrate the epidermis, cause sunburn, and can lead to DNA damage.
UVC: Ultraviolet C rays have the greatest energy but do not penetrate the earth’s atmosphere.

The sun’s effects on your skin

1. Sunburn

Mainly caused by UVB rays, sunburns can result in first-degree or second-degree burns. Sunburned skin is very sensitive to the sun, and is the result of an inflammatory reaction. Sunburns first appear a few hours after sun exposure, reaching their peak at the 24-hour mark. Eventually, burned skin cells peel off.

2. Tanning

Tanning is a natural protective reaction. A tan appears two to three days after exposure and will remain for three to four weeks. UVA and UVB rays cause tanning by activating melanin, a pigment synthesized by skin cells that protects your skin from UV rays.

There are two kinds of melanin: eumelanin, which gives a brown-black tint, and pheomelanin, which yields a more reddish-orange hue. These two pigments are distributed differently for different skin tones. This is why some people are more or less sensitive to the sun, and why we all tan differently.

3. Skin aging

When UVA rays penetrate the skin, they act on the cells responsible for skin elasticity. UVA alters these cells, causing a loosening of the skin and the formation of “wrinkles”.

4. Other short-term effects

There are many other short-term effects of sun exposure. For example:

Heat: This occurs during sun exposure.
Skin thickening: UVB rays activate the synthesis of skin cells called keratinocytes, which causes a thickening of the outermost layer of the skin. Along with tanning, this is one of the skin’s defense mechanisms against the sun.
Acne: In general, skin problems improve with sun exposure. However, thickening of the skin leads to the formation of new impurities, which can cause acne.
Drying: This is due to natural dehydration caused by heat.

How can you protect your skin from the sun?

There are a number of factors to take into account to adequately protect yourself from the sun and its effects. First of all, it’s best to avoid exposure during the sunniest hours of the day (11:00 am to 4:00 pm).

Next, you need to choose skin protection that’s suitable for your skin type. As discussed above, different skin tones react differently to the sun. Light skin tends to redden and burn quickly, while darker skin tans more easily.

When selecting a sunscreen, it is important to make sure that it will protect you from UVA as well as UVB rays. The filters in sun protection products will play a protective, anti-UV role. There are two kinds of filters: physical and chemical.

1. Physical filters

The best-known physical filters (also known as inorganic barriers) are titanium dioxide and zinc oxide. Made from minerals, they form a physical barrier between UV rays and the skin. These oxides give sunscreen its white tint. Physical filters are active as soon as sunscreen is applied, and present fewer allergy risks than chemical filters.

2. Chemical filters

Chemical filters (also known as organic barriers) are molecules that undergo chemical reactions on the skin’s surface and absorb UV rays. They take effect 30 minutes after application. Harmful to the environment, chemical filter ingredients are responsible for the destruction of coral reefs.

Your sun protection should be adapted to your phototype (skin tone, sun sensitivity…), exposure conditions (duration, time of day, if you’re swimming, if there’s snow or water reflecting sunlight…), and to your location (for example, stronger protection is necessary at higher altitudes).

It’s important to note that SPF (sun protection factor) provides an index of protection against UVB rays only. According to Health Canada, there is no authorized protection index against UVA rays. Products may only indicate that they are “broad spectrum”. This means they protect against both UVA and UVB rays, if they have ingredients (such as titanium dioxide and zinc oxide) that reflect ultraviolet radiation.

Now you know how to protect yourself from the sun. This article is of course not exhaustive, and is not a substitute for specialized professional advice!