Once you’ve determined which surfaces have mould on them, you should keep the UV-C lamp around two inches away from the mould in question. Every other light source in the room will need to be turned off in order for the UV light to get rid of all of the mould. This includes any doors and windows that could let small amounts of light in. Leave the room for a period of 1-2 hours, after which the mould should be eliminated. Repeat this process for any surfaces where mould has been found.
Make sure that you avoid looking directly at the light once it’s turned on. While there are special UV glasses that will protect your eyes, your eyesight could be damaged if you’re wearing standard eyeglasses. Whenever you handle a UV bulb, it’s important that you wear gloves of some sort to keep the bulb from damaging your skin.