LessWrong researcher refutes Steve Byrnes's claims that non-sunburn UV exposure is safe, calling his sunscreen avoidance advice dangerous

Steve Byrnes claimed non-sunburn sun exposure does not increase skin cancer risk and recommended people stop using sunscreen, which the author argues is incorrect and harmful

Both UVB and UVA radiation cause DNA damage through different mechanisms—UVB causes direct damage while UVA causes damage via oxidative stress

Cyclobutane pyrimidine dimers (CPDs), abnormal DNA structures created by UV exposure, are a primary cause of melanoma and can form without sunburn occurring

The author emphasizes that mechanistic understanding of UV-induced carcinogenesis supports the conclusion that non-sunburn exposure still causes cancer risk