Cook County Public Health: Besides the airport, a person infected with measles visited a food store, a Marshalls and a medical care clinic. Measles can remain in the air for up to 2 hours after the infectious person has left an area. "Measles is a highly contagious respiratory disease that spreads easily through the air when an infected person breathes, coughs or sneezes. Measles is so contagious that if one person has it, 90 percent of the people close to that person who are not immune or are unvaccinated will also become infected with the measles virus. The virus can linger in a room for up to two hours and can be especially dangerous for babies and young children, pregnant women, and people with compromised immune systems."