When sunbeds first became popular in the Seventies they produced mainly UVA radiation, thought to be the "safe" part of sunlight that tanned without burning. Today's more powerful lamps still use high levels of UVA but now often also contain UVB, which, as well as tanning, is responsible for sunburn and most forms of skin cancer. The faster the tan, the higher the dose of UVA/UVB radiation, with some sessions delivering a dose equivalent to sunbathing in the midday sun without a sunscreen.