Thanks Man...:)
air or water ... the same effect?
No, it is no issue.
As soon as the needle in exposed to air the virus is killed in seconds as the HIV virus cannot survive ANYWHERE except inside the human body.
Your friend in 100% safe.
Good luck
If your friend stepped on a needle, he should seek medical attention. HIV is not the concern. Your friend would have a pretty serious injury that could result in a bacterial infection.