If your sunscreen does not have SPF then you will be facing various risks such as premature aging, tanning, skin cancer, sun burns, etc. So, let us look at what is SPF and how it works to protect us from these dangers.
What is SPF?
Sun protection factor or SPF measures how much radiation (UVA & UVB) would burn your skin that is protected by sunscreen compared to quantity of radiation required for burning unprotected skin. For instance, if someone is using a sunscreen with SPF30 then it will be protecting the skin till the time it is exposed to thirty times more UV radiation compared to what is required for burning someone's totally unprotected skin.
This means that if the unprotected skin burns in ten minutes after exposure to sun rays, SPF30 sunscreen will protect the skin for as much as five hours (10 mins x 30 times = 300 mins or 5 hours) from harmful sun rays.
In addition, SPF 30 is able to absorb around 97% of harmful UVB rays while SPF 15 sunscreen will be absorbing around 93% of these harmful rays. Similarly, SPF50 will be absorbing almost 98% of harmful UVB rays.
How SPF works?
When your skin is exposed to UVB rays, the damage occurs in the skin's outer layer known as epidermis while UVA rays reach deeper into the dermal layers. SPF present in your sunscreen reflects or absorbs these harmful sun rays and protects your skin from damage such as premature aging, tanning, skin cancer, etc. Broad spectrum SPFs are capable of protecting you from UVB as well as UVA rays.
Types of SPFs
Mineral or Physical SPFs
These SPFs result in formation of a layer over the skin and are also known as sub blocks due to their ability to block off UV rays. If you have skin that is prone to acne then physical sunscreens are recommended since these do not clog pores on your skin. But, if you are using a makeup then these are not the most suitable option since they appear greasy and thick on the skin.
These are known to skin within the skin and tend to absorb harmful UV rays. Compared to physical or mineral SPFs, these are less greasy and appear thinner. If you are planning to apply makeup then use the sunscreen before it. These SPF based sunscreens are also the right choice when someone has a dry skin.
Reapplication of Sunscreen
Due to exposure to sunlight, the sunscreen you apply breaks down after a period of time, necessitating reapplication. The frequency at which you need to apply sunscreen depends on time spent outside in the sun. For instance, if someone was working in the office the whole day then sunscreen applied in the morning will remain good for evening travel.
But, if someone spends more time under the sun then the sunscreen should be applied at an interval of every two hours to get required protection from harmful rays of sun. similarly, if someone is sweating or swimming then it is likely that the sunscreen will be wearing off and should be applied within two hours of previous a