Yes. Ultraviolet radiation from the sun—and from tanning lamps—causes skin cancer. The WHO and IARC list UV as a Group 1 carcinogen. That is the same evidence bucket as tobacco smoke, not a blog rumor.

This is a summary of that evidence for planning outdoor time. It is not a diagnosis and it does not replace a skin exam.

What the data actually say

More UV, more skin cancer—across population studies, lab DNA work, and clinic patterns. Recent IARC-linked analyses attribute on the order of four in five melanomas worldwide to UV. That is a fraction of cases, not a claim that every sunburn becomes melanoma.

UVB burns the surface; UVA goes deeper

UVB is the main sunburn band and can form thymine dimers in DNA. UVA reaches further and adds oxidative damage. Broad-spectrum cover is not marketing language; it is both wavelengths. Cells repair a lot of this. Years of extra dose can outrun repair.

• Basal cell carcinoma — most common; usually slow, often tied to cumulative sun.
• Squamous cell carcinoma — also cumulative outdoor time.
• Melanoma — less common, more dangerous; both lifetime dose and sharp childhood burns show up in the risk story.

There is no published “safe tan dose.” Risk rises with exposure.

Tanning beds are not a gentler UV

IARC also puts indoor tanning devices in Group 1. The American Academy of Dermatology advises against them, especially under 18. Intensity can exceed midday sun.

Fair skin, lots of outdoor hours, family history, and a childhood of blisters raise personal risk. High altitude and low latitude raise the environmental dose—see where UV runs highest. Habits still dominate: shade, clothing, SPF 30+ every two hours, and no intentional burn.

Check today’s number on the live UV index before a long outdoor block.