Customs and health officials at O'Hare are taking passengers' temperatures with digital no-touch thermometers. Passengers will also be asked whether they've been near anyone sick.
PHOTOS: Ebola Virus 'entry screenings' begin at O'Hare
Some international travelers said they had long waits coming through U.S. Customs Thursday, as some say there were a few extra questions about their travel and health.
"Whatever they need to do to make everybody safe I suppose is fine with me," said Jamie Joffe, an international traveler.
George Sarpong is visiting from Ghana, which has not had any Ebola cases.
"I think these are very good questions actually, they asked me how I'm feeling, pretty much I'm feeling okay, I think they're doing a good job," Sarpong said.
Still, many others tell us they were not asked those questions as Ebola screening began at O'Hare.
About 150 people travel daily from those West African countries to the United States. Nearly 95-percent of them enter the country through New York, Chicago, Newark, Atlanta or Washington, D.C. airports. About a dozen people from Sierra Leone, Liberia and Guinea land in Chicago each day, officials said.
The Ebola entry screenings are considered another layer of protection to halt the spread of the virus, which has killed thousands of people in West Africa. A traveler from Liberia died after being admitted to a Dallas hospital, and two nurses who helped care for him have since been diagnosed with the disease.
Ebola is not contagious until symptoms begin, CDC officials said. Screening began earlier this week in New York, and on Thursday at the other airports.
Officials said any passengers who may show symptoms will be rushed to the hospital.
Presence Resurrection Medical Center is less than five miles from O'Hare, and already has an arrangement with the airport to screen passengers for other contagious diseases like malaria and MERS. Rush University Medical Center at the Illinois Medical District west of the Loop is also available and equipped to take travelers showing signs of Ebola.
Illinois Poison Center doctors, pharmacists and nurses are also being trained to answer questions Ebola.
The Chicago Call Center set up an Ebola hotline with the State Department of Public Health, which can be reached 24/7 for questions relating to the virus. The hotline number is 800-889-3931.
"We hope that it never happens, we hope that Ebola never lands, but when it does land, we want to make sure that the right information is in the general public, the right information is in the hands of healthcare providers, and that our hospitals and health care providers are ready to respond," said Dr. Michael Wahl of the Illinois Poison Center.