Do we need to fear the sun?

There is nothing like a bright sunny summer day to lighten up your mood. The sun is an essential component in the process of vitamin D synthesis in our skin, required for normal development and functioning of the bones. Yet exposure to the sun is not without any consequences.

Before talking about the risks associated with sun exposure, let’s have a look at the general principles of ultraviolet radiation (UVR) for a better understanding of what we will be discussing next.

The sun emits UVR which is of three different forms depending on the wavelength: UVA, UVB and UVC.                     

fig. the longer the wavelength of the UVR the deeper the penetration.

Although UVA is less harmful than UVB in its ability to cause cancers, the high amount of UVA that reaches the earth’s atmosphere and the ability of UVA to penetrate deeper into the skin makes protection against UVA it as important as protection against UVB.

How our skin protects us against the harmful UVR?

Besides the ozone layer which absorbs the harmful UVR and preventing it from reaching the earth’s surface, our skin also plays an important role in protecting our body against the UVR.

Our skin acts an effective barrier preventing the penetration of the UVR beyond the dermis (deeper layer of skin) and into the internal organs. Our skin is also equipped with various defence mechanisms such as enzymes and antioxidants which help repair the damage to the cells produced by UV exposure.

But in the process of protecting us from the UVR, certain light absorbing substances (called chromophore) undergoes a photo-chemical reaction that results in damage to the skin cells which results in sunburn, allergic reactions to the sun and if the body fails to repair the damage, the mutations can lead to skin cancers. Therefore the skins bears the maximum detrimental effect of the sun. 

So, do we need to fear the sun?

My answer is “YES”, especially if you’re person with Fitzpatrick skin type I-II, who have the maximum risk of UV induced skin cancers (see the previous blog post: “Do you know your skin type?“). Sun protection in these individuals is necessary from a very young age as risk of melanoma (a malignant cancer of the skin) is more with intense intermittent sun exposure from a very young age.

Sun protection is also necessary to prevent early signs of ageing and for individuals with pigmentation disorders or individuals with photodermatosis ( skin diseases caused solely due to the body’s abnormal response to the UVR) or genetic disorders such as xeroderma pigmentosa (inherited disease caused by a mutation that affects the ability of the body to repair the DNA damage produced by the sun).

That being said, fearing the sun does not mean you live under a rock and never see the sunlight again. As I did mention we need the sun for Vitamin D synthesis, and a few minutes of sun exposure two times a week is adequate for this normal process to occur. My advice is for you to understand when and where the danger lies and how to minimise it.

When and where is the sun’s UVR the maximum?

Areas near the equator receives maximum UVR.

fig. the red band represents where earth receives maximum UVR.

Higher the altitude more the UVR (Shimla, Jammu and Kashmir etc), even though these places are relatively colder, sun protection is still a must due to the shorter UVR path.

The time of the day when the sun is directly overhead i.e around noon time (9am- 3pm) is the time when sun protection has to be at its maximum. Early morning and late afternoon sun’s rays are directed at an angle to the earth’s surface and are mostly absorbed.

What if it is cloudy outside?

Clouds can reduce (though not by a great amount) the UVR reaching the earth but in days with scattered clouds, the UVR may even be more as most of the radiation are scattered. So my fellow Meghalayians (people hailing from a state in India call Meghalaya), you still need that sunscreen even if you live in a state whose name literally translates to the “Abode of clouds”

Abode of the Clouds (CC BY 2.0: Rajesh Dutta)

And what if its snowing outside?

Snow and sand, sea, are a good reflector of UVR which can double the risk of UV exposure.

In future posts we will explore the ways of proper sun protections. In the meantime remember that packing a sunscreen for your skiing trip at the Alps is as important as packing your sunscreen for a day at the beach.