HIV cannot survive in an open-air environment for more than a few moments. Because the virus cannot survive in the open air, those living in a home with someone who has AIDs do not need to sterilize common living areas. According to AVI.org, standard cleaning is all that is needed in most areas.
HIV is usually transferred to other individuals via shared bodily fluids during sex or through contaminated blood or needles. The area inside of a needle can insulate the virus from open air, especially if fluids or other matter are also inside the needle. Using a new, clean needle ensures there is no contamination.