Your skin protects you from the environment, but it needs a bit of help to protect you from UVA and UVB rays.
Ultraviolet light (UV light) is radiation from the sun and is invisible to the human eye. UV light can penetrate deep into our skin and is responsible for sunburn, the formation of free radicals that can damage our skin, and for increasing the risk of skin cancer.
Sunscreen helps protect your skin against damage caused by exposure to UV rays. There are two types of UVA/UVB filters that can be used in sunscreen to help block off UV radiation – mineral (physical) and chemical. Mineral and chemical sunscreens use different types of UV filters to achieve sun protection.
Mineral sunscreen. Mineral UV filters (typically zinc oxide and titanium oxide) work in a unique way, creating tiny mirrors that reflect and scatter sunlight away from your skin. These are usually classified as physical filters, and they might leave a white film on the skin.
Chemical sunscreen. Chemical UV filters absorb damaging UV rays and convert them into thermal energy which is released it from your skin.
UVA filters protect the skin from UVA rays, which make up 95 percent of the UV light reaching the Earth's surface. UVA rays also penetrate deep into the skin and are known to contribute to speeding up the skin aging process.
Similarly, UVB filters protect the skin from UVB light, which is the main cause of sunburn and the development of skin cancer. It only penetrates the outer layers of the skin but is no less dangerous than UVA light.