How do sunscreens work?

After the 1 part of our article on the sun, we understand a little better why our parents insisted so much so that we put our sunscreen religiously! It is very important to protect yourself from the sun. Have you wondered how concretely it works sunscreen? We unravel the mystery in this second article!

What is sunscreen?

Specifically, it is a product that contains active ingredients that protect us from UV rays. It exists in many forms, textures, brands, etc. , but overall, their role is always the same: to protect us. To achieve this, sunscreens contain UV filters. These can be either physical, chemical, or both.

The chemical filters are probably the most widespread and also the most controversial ... have you ever heard that sunscreen is as dangerous as the sun? Well, we were definitely talking about chemical filter creams.

Their principle is simple: they absorb uv rays ... by converting them into heat. (We remember here the law that says: nothing is created, nothing is lost, everything is transformed ...) In this way, it is as if the rays were "deactivated" and therefore less dangerous for us. The most common chemical filters are avobenzone, homosalate, octocrylene, oxydobenzone, etc. These ingredients are considered pharmaceutical and must therefore have a drug identification number (din) and pass a series of tests and forms prescribed by Health Canada.

The physical filterss (or mineral filters), for their part, work by diffusing and reflecting UV rays. They are often perceived as barriers that block the rays, by name, but that is not exactly how they work. The most common are zinc oxide and titanium dioxide. Unlike chemical filters, they are considered by Health Canada as natural products.

As a rule of thumb, a good, well-formulated sunscreen will work very well, whether chemical or physical, and the application modalities will remain the same. In the last part of our articles on the sun, we will do a little tutorial to help you decide which one to choose.

The FPS?

The sun protection factor (SPF) is indicated on all sunscreen labels. It is "a relative measure of how long it would take for unprotected skin to burn in the sun compared to the time it would take if the recommended amount of sunscreen was used. " In theory, with an 30 FPS, we could spend 30x more time in the sun without catching sunburn. Be careful: the theory and the practice are very different, so we do not take this rule for granted ... several other factors come into play. The FPS also tells us about the proportion of UVB rays blocked by sunscreen:


% of UVB radiation blocked













As the table above shows, we do not double the% of blocked radii if we double the SPF. Beyond FPS 60, it's usually more marketing than anything else.

Broad spectrum sunscreen

As we saw earlier, the sun's rays are divided into several categories. When talking about a broad spectrum sunscreen (and that's what you need to look for), it means protection against UVA and UVB rays. So honestly, as long as you take the trouble to apply sunscreen .... As well take a completely effective!

Expiration date?

We often think that even if a product has expired, it is still good, and although it is true for many items, do not take chances with sunscreens. If it's expired, get another one.

Now that we've covered the sun and sunscreens, there's still a good story: How to choose a sunscreen and how to use it! See you tomorrow for the last article of this week on the sun!

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