The UV filters in sunscreen prevents UV damage by forming a protective layer on your skin and either deflecting or absorbing harmful UV rays. Some absorb the UVB part of the spectrum, which is known to cause sunburn and increase skin cancer risk. Others absorb the longer wave UVA part of the spectrum believed to cause skin cancer through DNA damage.
What is SPF?
SPF stands for sun protection factor. It measures how much UV gets through the sunscreen. The higher the number, less UV passes through.
An SPF of 30 allows 3.3% of UV to reach your skin and thus filters 96.7% of UV. With an SPF of 50, 98% is filtered and 2% gets through.
SPF 30 is more than adequate to provide protection.
There are two main types of sunscreens (chemical/physical) and most sunscreens will contain both.
Comparing Chemical vs Physical sunscreen
| Chemical sunscreen | Physical sunscreen | |
| How does it work? | Absorbs sun rays | Deflects or blocks the sun rays, Higher UVA protection |
| Cosmetically acceptable? | Yes, but doesn’t leave skin looking white | Thicker in consistency
Skin looks white |
| How long does it take to work? | Must wait 20 minutes after application | Starts working immediately after application |
| Irritation? | Can be irritating to the skin | Titanium dioxide can cause breakouts
Zinc oxide is well tolerated. |
| Cost | Cheaper | More expensive |
How much should I use?
Generally, a tea spoon (5 grams) to every body part or more is needed. Don’t forget the ears, scalp (if thinning hair), neck, back of the hands and décolletage. Application depends on your activity.
How often to apply?
Always read the label on instructions of sunscreen as it may vary. Start by using it every morning and topping it up depending on your activity. Usually apply twice a day, but if you are going to sea/water/snow use it 3-4 times a day.
Find the right type of sunscreen that suits and agrees with your skin. I usually use different types of sunscreen (one for everyday, one for gardening and one for the beach).