Chemical sunscreens are the type that people will be most familiar with and the most easily accessible. Chemical sunscreens work by absorbing the sun’s rays. Some chemicals may scatter they rays, but mostly they absorb them.
The common ingredients in chemical sunscreens are avobenzone, octylcrylene, octinoxate, octisalate, oxybenzone, homosalate, helioplex, 4-MBC, uvinul T 150, uvinul A Plus, mexoryl SX and XL, and tinosorb S and M. Most over the counter sunscreens contain one or more of these ingredients.
The chemical ingredients are often more irritating to the skin. If it gets in your eyes they can water and sting. They are also known to cause allergic reactions.
Chemical sunscreens offer more UVA/UVB protection, but the level of protection depends on which active ingredient is used. After applying, you must wait 20 minutes before the chemical sunscreen to be effective. Usually the chemical sunscreens are colorless, odorless, and runny in texture.
In general, chemical sunscreens are safe but some of the ingredients create free radicals which cause irritation, damage, and aging of the skin. Many of the chemical ingredients are not even approved by the FDA in the US but they are used in Europe and Asia.
Physical sunscreens, on the other hand, are the complete opposite from chemical sunscreens. Physical sunscreens may be referred to as mineral sunscreens. They work by deflecting or bouncing the sun’s rays from the skin. Ingredients that are found in physical sunscreens are zinc oxide and titanium dioxide. Titanium dioxide may irritate some people but it’s far less problematic when compared to chemical sunscreens. Zinc oxide doesn't really cause problems. It’s safe for delicate and sensitive skin and it’s the main ingredient in diaper rash cream.
Protection wise, zinc oxide protects against the entire spectrum of UVA and UVB rays. Titanium dioxide protects against UVB rays but not the full spectrum of UVAs. Physical sunscreens immediately begin protecting after application.
The texture of this type of sunscreen doesn't tend to be as nice as the chemical formulations. Physical sunscreens are harder to apply and are thicker and more opaque. They also tend to leave a tint which is known as a white cast.
Where sunscreen is concerned it’s best to get physical! You best bet this summer is to find a physical or mineral sunscreen that contains zinc oxide and has an SPF of 30. SPF 30 is 97% effective and anything higher than 30 will only be 1% more effective. A physical sunscreen may be a little harder to find and cost a bit more but it’s your best bet to prevent damage from the sun.