The most common clinical condition that can cause AIDS is occupational exposure to HIV. The so-called AIDS occupational exposure generally occurs when medical personnel or police officers are stabbed or cut by knives or needles stained with the blood of AIDS patients in the course of their duties or work, which indeed has a great potential to cause the spread of AIDS. Once this happens, you need to immediately go to a regular tertiary hospital or CDC to take HIV blocking drugs. However, if the needle is contaminated with the blood of an AIDS patient and is exposed to air for a long time before stabbing others, the risk of HIV transmission is relatively small. Because HIV is not generally contagious when exposed to the air.