http://www.nytimes.com/2002/12/27/international/americas/27CHIL.html
Battling UV in southern Chile: “On a typical day here this month, the solar stoplight was set at orange, the second highest of four levels, and people were warned to limit their exposure to the sun between noon and 3 p.m. to 21 minutes at most.” (Despite the precision, it seems that they’re more being careful than responding to any science in particular.)