Long term exposure to all forms of UV light is bad, but UVA generally not a wavelength to be too woried about. They are commonly used in insect traps and the distsance from the source is sufficent to not present a health issue. As with all morms long term and high levels of radiation shoudl be avoided.
The biggest use of UVA lamps (Also know as "Blacklight") is in insect traps. these lamps product light in the the spectrum that flys can see and it lures them to the treaps. UVA lamps are also used in cureing processes usually glues and inks. Some curing processes require a different wave length and it is best to check your specifications before buying. the lamps typically peek at 368nm.