June 14, 2021

Sun Care Guide - UVA & UVB, SPF & Sunscreens

Preventing sun related damage is key to youthful skin and one of the best and cost-effective anti-aging strategies. Using broad-spectrum, high - 30 to 50 SPF during the day and avoiding prolonged/excessive exposure to sun will benefit your skin in a long term.

It is never too late to adopt this strategy!

The long-term effects of excessive sun exposure and not using sunscreen products lead to:

  • Pre-mature skin ageing (fine and coarse wrinkles, roughness in skin texture and extreme dryness)
  • Excessive pigmentation problems and freckles
  • May cause/increase risk of skin cancer Sun care, preventing freckles and over pigmentation

EXPOSURE TO UV LIGHT, UVA & UVB EXPLAINED

UV light penetrates skin depending on in its wave length:

  • Shorter wavelength (UVB) are mostly absorbed in the epidermis, affecting predominantly keratinocytes and are responsible for skin reddening and sunburn
  • Longer wavelength (UVA) penetrate skin deeper, affecting both keratinocytes in epidermis and dermal fibroblasts, and are considered the ageing rays

UV-A is 'Ageing' and  UV-B is 'Burning'

About 50% of UV damage is caused by formation of free radicals. An increase of ROS (Reactive Oxygen Species) cause oxidative stress leading to tissue damage:

Most of UV – related damage in photoaged skin are apparent in the dermis, with damage to elastic fibres, loss of collagen and disruption to dermal matrix.

TYPES OF SUNSCREENS

  • Physical sunscreens (also called mineral sunscreens) use natural ingredients zinc and titanium dioxide – they stay on top of the skin, deflecting harmful UV radiation away from the skin. The older type of this kind of sunscreens would leave a white residue on the skin. The newer physical sunscreens are formulated with nano (ultra-small) size particles and/or come tinted, no longer leaving a thick, white layer on the skin.
  • Chemical sunscreens are formulated to absorb UV rays, and by chemical reaction convert them into heat to ultimately release them from the body. The key ingredients you may found in chemical sunscreens are: avobenzone, benzophone, octocrylene, octisalate, octinoxate and oxybenzone
  • Physical & chemical sunscreens combined using the combination of physical sunscreens usually in nano (ultra-small size particles) of either titanium dioxide or zinc and chemical screens.

WHICH SUNSCREEN TO CHOOSE?

Physical sunscreens made with mineral active ingredients, such as zinc oxide and titanium dioxide provide strong sun protection with few health concerns and don’t break down readily in the sun. They tend to be less irritating to sensitive skin and a lot of dermatologists recommend using physical sunscreen if you suffer from rosacea, acne and/or sensitive skin.

For those who need a water-resistant formulation and/or want a light sunscreen that absorbs quickly into the skin – the chemical sunscreen would be a better choice.

SPF EXPLAINED

SPF, SPF 15, SPF30, SPF50, Sunscreen tube

SPF (Sun Protection Factor) value reflects only how well a product will protect from UVB rays, the main cause of sunburn and non-melanoma skin cancers.

  • SPF15 blocks 93.3% UVB
  • SPF30 blocks 96.7% UVB
  • SPF50 blocks 98% UVB
  • SPF100 blocks 99% UVB

SPF does not cover protection from UVA rays which cause skin ageing and cancer.

Key things to know:

  • High-SPF products suppress sunburn much more effectively than they protect from UVA-induced damage
  • Correctly applied, sunscreens with SPF 30 to 50 offer sufficient sunburn protection, even for people most sensitive to sunburn
  • There is lack of data showing that sunscreens with SPF values above 60 provide additional meaningful clinical benefit
  • Don't rely on sunscreen alone. 

CONCUSIONS:

Avoiding prolonged /excessive exposure to sun and wearing sunscreen daily is a must to:

  • Keep your skin in good health
  • Keep your skin looking younger for longer

 

Dermatologists recommend SPF 30 -50, with a broad UVA & UVB protection, applied 15 to 30 minutes before going out on the sun and reapplied every 2 - 3 hours.

 

References:

1) Anti-aging and Sunscreens: Paradigm Shift in Cosmetics; Shreya Shanbhag, Akshatha Nayak, Reema Narayan, and Usha Yogendra Nayak

2) New Trends in Antiaging Cosmetic Ingredients and Treatments: An Overview; Peter Clarys and Andre O. Barel

3) EWG’s Sunscreens Guide

4) Natural and Sun-Induced Aging of Human Skin; Laure Rittié and Gary J. Fisher

5) The Skincare Bible. Your No-Nonsense Guide to Great Skin.; Dr. Anjali Mahto