Everybody loves being out in the sun, whether it’s a day out on the beach or a quiet sun soaked afternoon. But the skin needs protection from the sun too no matter how long or what time of the day you choose to go out. Sunscreen is one solution for sun protection and you might hear skin specialists prescribing sunscreens with a certain SPF value. So what does this SPF value mean and why are higher values preferred in a sunscreen? Let’s try to understand.
What is SPF?
SPF is short for Sun Protection Factor. It is a measure of how much solar energy (UV radiation) is required to produce a sunburn on protected skin. As SPF value increases, so does the amount of sun protection.
A Common Misconception about SPF
A common mistake that a lot of people make when understanding SPF is that it is equivalent to the amount of time they can spend in the sun. This is simply not true. SPF is not directly related to the time of sun exposure but to the amount of sun exposure. The latter is influenced by a variety of factors.
What is the Significance of SPF in Sunscreen?
SPF is a factor that protects your skin from UV rays. For that reason, it is essential to wear sunscreen with a good SPF value. There are broadly two types of sunscreens. Ones that absorb the sun rays and release them as heat and the ones that scatter them off your skin. A good SPF value is important in a sunscreen because it delays the amount of time before the sunscreen wears off and starts being ineffective.
SPF Numbers Explained
The sun’s harmful UV rays are further composed of UVA and UVB rays. UVB rays pose the highest risk of skin cancer while UVA rays can cause tanning, aging and wrinkles. The SPF value in sunscreens is the amount of protection it offers from the UVB rays. For that reason, it is important to look for “broad-spectrum” sunscreen because that offers protection against UVA rays as well.
Do High SPF Provide Better Protection?
In an ideal environment (i.e. a lab), a broad-spectrum sunscreen with SPF 50 would provide better and prolonged protection. But in the real world, products with high SPFs create a false sense of security. With them applied, people tend to stay out more and skip reapplying resulting in increased risk and thus defeating the purpose of the product. Here are some stats for understanding SPF.
- SPF 15 blocks 93%
- SPF 30 blocks 97%
- SPF 50 blocks 98%
- SPF 100 blocks 99%
Note: No sunscreen can block 100% of UVB rays.