What is SPF and how does it work?
When it comes to protecting your skin from the harmful effects of the sun, a good sunscreen is critical. But how exactly do sunscreens work? Let's dive into the actual ingredients and science behind high performance sunscreens.
What are UV rays and why are they harmful?
Ultraviolet radiation (UVR) is a form of electromagnetic energy emanating from the sun. There are three types of UV rays: UVA, UVB, and UVC. UVC rays are absorbed by the ozone layer and do not reach the Earth's surface, but UVA and UVB rays can cause damage to the skin.
How do sunscreens protect the skin?
Sunscreens work by either absorbing or reflecting UV rays before they can hit the skin. Chemical sunscreens, more properly referred to as organic sunscreens, absorb UV radiation and convert it into minute amounts of heat. Physical sunscreens, also known as mineral or inorganic, both absorb and reflect UVR but, contrary to popular belief, they primarily absorb it. This is especially true for zinc oxide. The two mineral sunscreens are titanium dioxide and zinc oxide, TiO2 and ZnO. So, organic and inorganic sunscreens work in similar ways. The big difference is that organic sunscreens are single molecules that completely disappear into the liquid, but inorganic sunscreens are tiny, solid particles that are simply spread out in the formula.
What is SPF and how does it work?
SPF, or Sun Protection Factor, is a measure of how well a sunscreen protects against the burning rays, mostly UVB but also a bit of UVA. The SPF number indicates how long it will take for UVR to just redden the skin when using the sunscreen compared to not using any sunscreen at all. For example, if it takes 10 minutes for your skin to redden without sunscreen, an SPF 30 sunscreen would theoretically protect your skin for 300 minutes, 10 x 30.
Are all sunscreens created equal?
Not all sunscreens are created equal. It's important to choose a broad-spectrum sunscreen that protects against both UVA and UVB rays. Additionally, water-resistant sunscreens are ideal for activities where you may be sweating or swimming. Note even water resistant sunscreens vary in how long they last but US regulations only allow a sunscreen to state it is water resistant for 40 or 80 minutes, even if it lasts longer.
Conclusion
Enjoy the outdoors but be smart. Wear a hat and choose a sunscreen with the right SPF and broad-spectrum protection to keep your skin safe and healthy.
