Hi how long do sperm survive outside air? and do hand sanitisers kill sperm?

Not long: Sperm don't live in the air, on clothes, or on other items. Their natural habitat is warm, fresh semen... not on household objects. Therefore, fresh semen on hands, condoms, etc., that is quickly put into a vagina can still lead to pregnancy. Realize that scientists are not spending time testing how likely or unlikely pregnancy would be in such situations. Hands wiped very dry should be safe.