The effort to screen travelers from the three West African countries most affected by Ebola started on Saturday at Kennedy and will be expanded over the next week to Newark Liberty, Washington Dulles, Chicago O'Hare and Hartsfield-Jackson in Atlanta.
Customs officials say about 150 people travel daily from or through Liberia, Sierra Leone or Guinea to the United States, and nearly 95 per cent of them land first at one of the five airports.
There are no direct flights to the US from the three countries, but Homeland Security officials said last week they can track passengers back to where their trips began, even if they make several stops. Airlines from Morocco, France and Belgium are still flying in and out of West Africa.
President Barack Obama said on Wednesday that the new screening measures support protections already in place.

Border Patrol agents already look for people who are obviously ill, as do flight crews, and passengers departing from West Africa are being screened.
Public health workers at Kennedy Airport will use no-touch thermometers to take the temperatures of the travelers from the three Ebola-ravaged countries; those who have a fever will be interviewed to determine whether they may have had contact with someone infected with Ebola.
There are quarantine areas at each of the five airports that can be used if necessary.
Health officials expect false alarms from travelers who have fever from other illnesses. Ebola isn't contagious until symptoms begin, and it spreads through direct contact with the bodily fluids of patients.
The extra screening at US airports probably wouldn't have identified Thomas Eric Duncan when he arrived from Liberia last month because he had no symptoms while traveling. Duncan, the first person to be diagnosed with Ebola in the US, died on Wednesday in Dallas.

Latest News from World News Desk