Sunscreen Explained: The truth behind the numbers
We all know that sunscreen is an important factor in preventing skin cancer and other sun damage, but do you really understand how sunscreen works or what SPF actually means? It’s not as straight forward as you may think, so let’s dive in and answer some of your burning questions about sunscreen (See what I did there? 😊 )
What is SPF?
SPF stands for Sun Protection Factor. Per the US FDA: “SPF is a measure of how much solar energy (UV radiation) is required to produce sunburn on protected skin (i.e., in the presence of sunscreen) relative to the amount of solar energy required to produce sunburn on unprotected skin. As the SPF value increases, sunburn protection increases.”
What’s the difference between SPF 30 and 50?
The number on sunscreen labels, such as SPF 30, SPF 50, SPF 70, and so on, denotes the Sun Protection Factor (SPF). This isn’t a measure of time, but a measure of the percentage of UV rays that are blocked before skin burns.
In lab-perfect conditions (i.e. – not real life) sunscreen with an SPF 15 blocks 93% of UV rays. With SPF 30 it jumps to 97%, while SPF 50 is about 98%.
But real life isn’t a lab, and how skin reacts to the sun is dependent on a variety of factors, including skin tone and the intensity of solar rays.
Your sunscreen will likely protect you from sunburn much longer in the winter months versus summer. And those of us in the Texas will have higher exposure to solar rays than those in northern states or Canada.
Is Higher SPF is better?
Well, technically yes, but don’t be fooled by those higher numbers. Realistically, anything over SPF 30 is going to offer an negligible amount of additional protection.
One of the problems with products with a high SPF number is they can give a false sense of security. People who use them tend to stay out in the sun much longer. They may skip reapplying. And they may think they don’t need to seek shade, wear a hat or cover up with clothing. They end up getting a lot more UV damage, which, of course, defeats the purpose.
Can I use the same sunscreen for my face and body?
Sunscreen will work the same way, regardless of the part of body it is used on. However, there are differences in the formulations for face and body products that take into account the differences in the skin.
Facial sunscreens are formulated to be lighter in texture, non-comedogenic (won't clog pores), and may include additional skincare benefits like antioxidants or anti-aging ingredients. Because of these additional components, facial sunscreens tend to be in smaller bottles and are more expensive.
On the other hand, body skin tends to be thicker, less sensitive, and may require broader coverage due to larger surface area exposure. Body sunscreens are more water-resistant for activities like swimming or sweating, and usually have a thicker consistency suitable for extended outdoor activities. Sunscreens for the body are easier to manufacture, come in larger bottles, and are typically less expensive.
How long can I stay in the sun?
It depends. It’s extremely important to understand that SPF is not directly related to the time of exposure to the sun.
Our fair-skinned readers know that they will burn more quickly than their friends with darker skin. And we all know that in our hot Texas summers there is a huge difference between the sun at 9:00am vs 2:00pm. The higher in the sky the sun is, the closer to the Earth it is, and the higher the exposure to solar rays.
While SPF 30 may protect you from a sunburn for an hour at breakfast, it may be more like 20-30 minutes at lunch.
Should I use chemical sunscreen or mineral sunscreen?
The decision to use zinc sunscreen or chemical sunscreen depends on various factors, including your skin type, personal preferences, and specific needs. Here's a breakdown of the differences between the two:
Zinc Sunscreen:
Physical or mineral sunscreen containing zinc oxide as the active ingredient.
Provides broad-spectrum protection against both UVA and UVB rays.
Works by creating a physical barrier on the skin's surface, reflecting and scattering UV radiation away from the skin.
Generally suitable for sensitive skin, as zinc oxide is non-irritating and non-allergenic.
Offers immediate protection upon application, making it ideal for outdoor activities.
Can leave a whitish cast on the skin.
Chemical Sunscreen:
Contains organic (carbon-based) compounds like avobenzone, octinoxate, or oxybenzone as active ingredients.
Absorbs UV radiation and converts it into heat, which is then released from the skin.
Provides broad-spectrum protection, but some chemical filters may degrade over time and with sun exposure.
Generally lighter in texture and easier to apply, with less risk of leaving a white cast.
Users with sensitive skin may experience irritation or allergic reactions to certain chemical sunscreen ingredients.
Ultimately, the best sunscreen for you is one that you will use consistently and adequately. If you have sensitive skin or prefer a more natural option, zinc sunscreen may be the better choice. However, if you prioritize ease of application and texture, a chemical sunscreen might be more suitable. Additionally, consider factors like water resistance, SPF level, and any specific skin concerns when making your decision. It's also worth noting that some people opt for a combination of both types for optimal protection and convenience.
There are so many variables. What should I do?
Apply and re-apply. Put on sunscreen 30 minutes before going outside and re-apply at least every two hours if you are in intense sun. If you are swimming, exercising, or sweating a lot, re-application might need to happen even more often.
And don’t just count on sunscreen. Clothing, hats, umbrellas, and shade are important factors in protecting your skin from harm.
Understanding sunscreen and SPF is crucial for sun safety. By debunking myths and adopting sun-safe practices, we can enjoy the outdoors while minimizing the risk of sunburn and skin cancer. Remember, sun protection is a year-round commitment, so prioritize your skin's health every day.