# What are UV levels and how can you protect yourself?
The sun emits ultraviolet radiation in three forms: UVA, UVB, and UVC. Earth's ozone layer filters out most UVC rays, but UVA and UVB penetrate our atmosphere and reach our skin. Both types damage skin cells and increase melanoma and non-melanoma skin cancer risk.
UVB rays cause the visible sunburn you feel after a beach day. UVA rays penetrate deeper into skin layers, triggering premature aging, wrinkles, and age spots. Unlike sunburn, UVA damage often goes unnoticed until years later.
The UV Index, measured on a scale of 0 to 11 or higher, tells you how intense ultraviolet radiation is on any given day. Higher numbers mean faster skin damage occurs. A UV Index of 3 or below is considered low risk. At 6 to 7, moderate protection becomes essential. Above 8, strong protection is necessary and outdoor time should be limited.
Vitamin D synthesis requires some UV exposure, typically 10 to 30 minutes of midday sun several times weekly for most skin types. Beyond this, protection becomes critical.
Effective sun protection combines multiple strategies. Broad-spectrum sunscreen with SPF 30 or higher blocks both UVA and UVB rays. Apply one ounce (about a shot glass full) to your entire body 15 minutes before sun exposure, then reapply every two hours or after swimming. Physical sunscreens containing zinc oxide or titanium dioxide work immediately, while chemical sunscreens need that 15-minute window to activate.
Seek shade during peak sun hours between 10 a.m. and 4 p.m., when UV intensity peaks. Wear protective clothing including long