DNA can be damaged by exposure to UV light. Of the three categories of solar UV radiation two types of UV radiation are of greatest concern to humans, especially as continuing depletion of the ozone layer causes higher levels of this radiation to reach the planet's surface.
References
-DNA Damage 2014, Scitable, accessed 4 March 2015, <http://www.nature.com/scitable/topicpage/dna-damage-repair-mechanisms-for-maintaining-dna-344>.