When does UV radiation become dangerous?

It is not clear when the risk of UV exposure becomes significant enough to warrant the need for an extended exposure to the sun, but the research shows that even the briefest exposure of an hour or so can pose an increased risk.

Researchers at the University of Southern California (USC) and the University at Buffalo found that the average person can be exposed to up to 4,000 micrograms of UV radiation every hour of every day.

This is equivalent to about five times the daily exposure of a typical person, according to the report.

The authors used data from the National Health and Nutrition Examination Survey (NHANES) to track how much people were exposed to each hour over the course of their lifetime.

They also looked at the number of deaths from UV-induced diseases, and found that people who died from any type of sunburn between the ages of 15 and 44 had the highest rates of UV-related cancers.

The study, published in the journal Environmental Health Perspectives, was funded by the National Institutes of Health.