The sun emits ultraviolet radiation in three forms. UVA and UVB rays penetrate Earth's atmosphere and reach your skin directly. UVC rays get blocked by the ozone layer. Both UVA and UVB damage skin cells and increase melanoma and non-melanoma skin cancer risk.
UVA rays penetrate deep into the dermis, causing premature aging, wrinkles, and age spots. UVB rays burn the outer epidermis layer and trigger the body's inflammatory response, creating visible sunburn. Repeated exposure to either accelerates cellular mutation and carcinoma development.
UV Index measurements, ranging from 0 to 11 or higher, indicate daily radiation intensity in your area. The scale accounts for sun angle, cloud cover, altitude, and ozone levels. An index of 6 or higher requires protection. Values change hourly. Peak UV exposure occurs between 10 a.m. and 4 p.m., when the sun sits highest.
Your body does need some UV exposure for Vitamin D synthesis. Just 10 to 30 minutes of midday sun several times weekly provides adequate levels without triggering damage. Skin tone matters here. Darker skin requires longer exposure for equivalent Vitamin D production but offers greater natural UV protection.
Protection strategies include sunscreen with SPF 30 or higher, reapplied every two hours and after swimming. SPF numbers indicate how long you can stay in sun before burning compared to unprotected skin. SPF 30 blocks roughly 97 percent of UVB rays. SPF 50 blocks 98 percent. Diminishing returns apply at higher numbers.
Seek shade during peak hours. Wear UV-blocking clothing, hats with wide brims, and sunglasses blocking 99 to 100 percent of UVA and UVB rays. Lightweight long sleeves and pants made from tightly woven fabric offer better protection than loose garments. Reflective surfaces like sand, water, and snow intensify exposure, so increase precautions near these