Danger. All of us are subject to radiation whether from the sun and space as well as all we face with standard x-rays and ct scans. The federal government is already worried with all the ct scans we get during our lifetime but the likelihood of overexposure at airports is not much in the overall radiation we get. Radon gas is a source that currently is unknown. Avoid any radiation if possible!
Zero. There is no risk. The dose is infinitesimal.