Why do people die if air bubbles get into their blood stream?

You will not die if a small amount of air is infused into a vein in a distant peripheral site, like your forearm. read more

Like Richard Hom said, air bubbles in the blood stream can cause air embolisms. However, not all bubbles cause embolisms, and not all air embolisms are lethal. Small bubbles are easily broken up by your bloodstream and cause no trouble - unless they're injected right into the brain or the heart. read more

More common is air entering accidentally via injection or IV tube, or when blood vessels are cut during surgery. Another possibility arises during ascent after scuba diving, where an increase in air volume in the lungs pushes tiny bubbles of air into the bloodstream that expand as you rise. read more

Air embolism occurs when one or more air bubbles enter a vein or artery and block it.Air embolism are deadly,cause it blocks the blood vessels thus causing local death of tissue.These air bubbles can travel to your brain, heart, or lungs and cause a heart attack, stroke, or respiratory failure. read more