Ultraviolet radiation from the sun exists on a spectrum, and understanding where you fall on that spectrum matters for your health decisions.
UV rays come in three types: UVA, UVB, and UVC. UVC rays don't reach Earth's surface because the ozone layer blocks them. UVA and UVB rays, however, penetrate through the atmosphere and affect your skin differently. UVB rays cause sunburn and directly damage DNA in skin cells, while UVA rays penetrate deeper into the skin and contribute to premature aging and skin damage.
The UV Index, measured on a scale from 0 to 11 and above, tells you how intense UV radiation is on any given day. A reading of 0 to 2 means low risk, while 11 and above indicates extreme risk. Weather apps and health websites typically display the UV Index for your location so you can plan accordingly.
Some sun exposure benefits your body. Sunlight triggers vitamin D production in your skin, and vitamin D supports bone health, immune function, and mood regulation. Most experts recommend 10 to 30 minutes of midday sun exposure several times per week for adequate vitamin D synthesis, depending on your skin tone and geographic location.
Beyond that threshold, protection becomes essential. Dermatologists recommend wearing broad-spectrum sunscreen with an SPF of at least 30, which blocks 97 percent of UVB rays. Apply sunscreen generously about 15 minutes before going outside, and reapply every two hours or after swimming or sweating.
Clothing offers physical protection that sunscreen cannot. Lightweight long sleeves, hats with wide brims, and UV-blocking sunglasses shield your skin and eyes from damage. Seeking shade during peak UV hours, typically between 10 a.m. and 4 p.m., reduces