I recently bought an insect repellent and noticed that it uses "ultraviolet black light". Will the use of this in my home increase my family's risk of developing skin cancer?"

There is no evidence to suggest that insect traps using ultraviolet black light increase your risk of developing skin cancer, as the amount of ultraviolet radiation they emit is very low. Black lights emit a type of ultraviolet radiation called UVA, which is invisible to the human eye. They are often used in industry, nightclubs or amusement parks to make things glow. This glow is the energy emitted by the light being converted into visible light by particles called phosphors. These particles are found in certain objects, including your teeth and fingernails. Many insects can see ultraviolet light so black lights are often used in the “bug zapper” type of insect traps. 

Black lights are usually fluorescent lamps or incandescent light bulbs modified to allow only the emission of UVA and some visible light. UVA is thought to cause premature ageing and has recently been linked to some skin cancers, however UVB is the main cause of skin cancer. Exposure to UVA from black lights is well below the recognised safe limits and is not hazardous to people using them, working in their vicinity or who have them in their home. Exposure from black lights would be much lower than your exposure to UVA outdoors.