Choosing the right sunscreen can be a daunting task. UVA, UVB, SPF, photostable and water resistant are some of the terms you’re likely to encounter. Let’s try to clear things up!
UVA and UVB radiation
It’s important to pick a sunscreen that blocks both UVA and UVB rays, since both types of radiation damage skin.
UVA rays penetrate deeply into the skin and primarily contribute to its premature aging . They account for the immediate tanning effect and for allergic reactions in people who are intolerant to sun exposure. UVA rays can also lead to pigmentation disorders (e.g. dark spots) and certain types of skin cancer.
UVB rays cause sunburn, a type of skin damage that should be avoided at all costs. They also account for tanning by increasing melanin production as a way to protect skin cells. As a result, UVB rays significantly increase the risk for skin cancer .
Sun protection factor (SPF)
A key factor to consider when buying sunscreen is its SPF – or sun protection factor. The SPF rating indicates the level of protection provided against UVB rays.
It is actually a multiplication factor used to determine the amount of UVB radiation needed to produce inflammation (a sunburn) on protected skin. But remember that no SPF offers 100 percent protection. For example, an SPF 15 cream blocks 93 percent of UVBs, while an SPF 30 product deflects 96.7 percent of them.
|SPF||% of UVB rays that penetrate skin||Multiplication Factor|
|No sunscreen used||100%||---|
|SPF 15||7%||You will need to be exposed to 15 times more UVB rays to get a sunburn vs. exposure without sunscreen.|
|SPF 30||3.3%||You will need to be exposed to 30 times more UVB rays to get a sunburn vs. exposure without sunscreen.|
Having the SPF indicated on the bottle is more than just a numbers game. You also need to use the product properly. This means applying a generous quantity and reapplying every 2 hours, after swimming or perspiring heavily.
The Canadian Dermatology Association (CDA) recommends the use of a broad spectrum sunscreen (which protects against both UVA and UVB) with an SPF of at least 30, starting as early as six months of age.
The more easily you get sunburnt, the higher your SPF should be. But don’t be lulled into a false sense of security by a high SPF number. It bears repeating that sunscreen will not protect you properly if you do not use enough of it or if you fail to reapply it as needed. Here are the guidelines you must follow:
- Apply sunscreen 30 minutes before going outside. A person of average size, wearing a bathing suit, needs about 2 tablespoons (30 ml) of product to cover his or her entire body.
- Reapply every 2 hours and after swimming or perspiring heavily.
- Protect your lips with an SPF 30 lip balm.
- Don’t forget sensitive areas of the body, such as the eye contour, ears and nose.
For optimal performance, sunscreen must contain filters capable of absorbing or deflecting UV radiation. Some sunscreens are formulated with organic filters or mineral filters. These provide very effective protection from the harmful effects of the sun.
Here are a few examples of common UV filters found in today’s sun protection:
- Mexoryl (SX or XL)
- Titanium dioxide
- Zinc oxide
- Avobenzone (Parsol 1789)
- Tinosorb M and S (bisoctrizole and demotrizinol)
These products are generally regarded as safe by the medical community. Some may, however, not provide adequate protection, particularly from UVAs. To make sure the product you buy blocks UV radiation, always look for the CDA logo. If you’re not sure, ask your pharmacist! He or she can let you know which UV filters can be found in a given formula and whether or not they provide the protection you need.
The latest UV filters, such as Mexoryl SX and XL, Tinosorb M and S, are photostable and deliver a high degree of protection at a relatively low concentration compared to other active ingredients. This reduces the risk of skin irritation and that’s great news for people with sensitive skin.
Photostability and water resistance
To perform well, a sunscreen must be able to withstand sun exposure without deteriorating. This is known as its “photostability.” If a product is not photostable, it will lose its effectiveness over time when in contact with the sun. So for greater peace of mind, be sure to pick a photostable product.
Water resistance is another key factor that determines the quality and reliability of a sunscreen. Products with little water resistance can lose their effectiveness, especially if a person is often in the water or perspiring heavily. Remember to reapply often, particularly after swimming or strenuous exercise. This goes for all products, even those that are water resistant.
What about children?
According to the CDA, babies under 6 months of age should not be exposed to the sun. Keep them out of direct sunlight, dress them in lightweight, loose-fitting clothing that covers their whole bodies and make sure they wear a sun hat. If sun exposure cannot be avoided , use a small amount of sunscreen on exposed body parts. Physical filters, such as zinc oxide, are preferred.
When choosing a sunscreen for your family, always look for a product with the CDA logo.
Did you know that certain medications can make your skin more sensitive to the sun? This reaction, known as “drug-induced photosensivity,” is mostly associated with UVA rays. Your pharmacist can tell you if a drug you are taking can cause photosensitivity.
Here’s another interesting fact: in Canada, sunscreens are considered drugs, not cosmetics. If you have questions about sun protection, talk to your family pharmacist or beauty consultant . They’re here to help!