Sunscreen is a product that is applied to the skin to protect it from the harmful effects of the sun’s ultraviolet (UV) rays. UV radiation is a type of electromagnetic radiation that is emitted by the sun and other celestial bodies. It is divided into three types: UVA, UVB, and UVC. UVA and UVB are the most harmful to humans, as they can penetrate the Earth’s atmosphere and reach the surface. UVA rays are longer in wavelength and can pass through glass, making them a concern even on cloudy days or when you are indoors. UVB rays are shorter in wavelength and are the main cause of sunburn. They are most intense during the middle of the day and are more prevalent at higher altitudes and closer to the equator.

Sunscreen works by absorbing, reflecting, or scattering UV rays, depending on the ingredients it contains. There are two types of active ingredients in sunscreen: chemical and physical. Chemical sunscreen absorbs UV rays and converts them into heat, which is then released from the skin. Physical sunscreen, also known as mineral sunscreen, works by reflecting and scattering UV rays away from the skin. It is made with ingredients such as zinc oxide and titanium dioxide.

It is important to use sunscreen when you will be spending time outdoors, especially during the middle of the day when the sun’s rays are the strongest. The American Academy of Dermatology recommends using a sunscreen with a sun protection factor (SPF) of at least 30, which blocks about 97% of UVB rays. It is also important to use enough sunscreen and to reapply it every two hours or after swimming or sweating. You should apply a shot glass-sized amount of sunscreen to your body, and use a nickel-sized amount for your face. Don’t forget to apply sunscreen to all exposed skin, including your ears, the back of your neck, and the tops of your feet.