Another reference is to UV-C, implying that UV-C is reaching those who sunbathe.
From the newscientist.com
Carry on to St George, a tiny rock-isle, to snorkel and sunbathe in seclusion.
From the guardian.co.uk
So, according to you, Kate can't sunbathe topless in private with her husband.
From the newsfeed.time.com
Now the streets are all paved and village children sunbathe in thong bikinis.
From the time.com
She loved to stretch out in the chaise lounge in the driveway to sunbathe, he says.
From the democratandchronicle.com
Tourists swim and sunbathe in the Black Sea resort town of Batumi in Georgia.
From the au.news.yahoo.com
People can sunbathe on their terrace or around one of our pools throughout the year.
From the charlotteobserver.com
Slovenia's a country in which you can ski and sunbathe on the beach in the same day.
From the couriermail.com.au
Presumably, women who sunbathe topless are hoping for an even, all-over tan.
From the guardian.co.uk
More examples
Sun: expose one's body to the sun
Sun tanning is the act of exposing the skin to ultraviolet (UV) radiation, for the purpose of darkening skin color, either during sun bathing or using artificial sources, such as tanning beds.