十万个为什么·科学启蒙30篇（1）
12 / 30
正在校验访问权限...
What Happens When You Get a Sunburn?
晒伤时身体发生了什么？
-
Sunburn is your skin’s inflammatory reaction to damage caused by ultraviolet (UV) radiation from sunlight or tanning beds.
-
UVB rays directly harm DNA in skin cells, triggering repair mechanisms and sometimes causing mutations that lead to skin cancer.
-
UVA rays penetrate deeper, breaking down collagen and elastin fibers that keep skin firm and youthful.
-
Within minutes of exposure, blood vessels widen and immune cells rush to the area, causing redness, warmth, and swelling.
-
Dead or damaged skin cells begin peeling off after a few days as your body replaces them with fresh layers.
-
Melanin—the pigment that gives skin its color—increases in response to UV, causing tanning, but this offers only minimal natural protection.
-
People with fair skin, light eyes, or many moles have less built-in melanin defense and burn more easily.
-
Severe sunburns blister because fluid leaks into upper skin layers, separating them from the deeper tissue beneath.
-
Repeated sunburns before age 18 double the risk of developing melanoma later in life.
-
Broad-spectrum sunscreen blocks both UVA and UVB, and reapplying every two hours ensures continuous coverage during outdoor activity.