A US study reported on the BBC and the WebMD makes for scary reading.
"The Mayo researchers found that between the late 1970s and 2003, the incidence of basal cell carcinoma skin tumors doubled among people younger than age 40, with the rise in cases among women accounting for most of the increase."
The articles recommend using sun cream of at least Sun Protection Factor 15 (SPF 15), and preferably above SPF 30 and re applying throughout the time that skin is exposed. More about the Healthy House sun screen here.