U.S. airlines will require passengers to answer a series of health questions before boarding, including whether they have experienced covid-19 symptoms or have been exposed to someone that tested positive for the virus, the industry’s leading trade group said Monday.

Major U.S. carriers, including American, Delta and United are implementing the new health acknowledgment policy as an “additional level of protection during the pandemic,” Airlines for America said.

Travelers should expect to be asked to fill out the new health questionnaire when they check-in, the airline trade group said. Besides questions about their health, passengers are asked to commit to wearing a face covering at the airport and on their flight.

“Passengers who fail or refuse to complete the health acknowledgment may be deemed unfit to travel and each carrier will resolve the matter in accordance with its own policies,” A4A said. The new measure is expected to remain in place through the public health crisis.

A4A President and chief executive Nicholas E. Calio said in a statement that the health assessments are one more measure in a “multilayered approach to help mitigate risk and prioritize the well-being of passengers and employees.”

Airlines and airports in recent months have adopted new strategies for combating the coronavirus. In some airports, travelers have their temperatures checked upon arrival, while all major airlines are enforcing the use of face coverings.

With the health questionnaires, airlines seek assurance from passengers that they are not experiencing covid-19 symptoms such as fever, shortness of breath and others such as a cough, loss of taste or smell, chills, muscle pain and sore throat.

Passengers will also be asked to acknowledge if they have been exposed to someone who tested positive or had symptoms of covid-19 in the last 14 days.

Other airlines enforcing the new health acknowledgment policies are Alaska Airlines, Hawaiian Airlines, JetBlue Airways and Southwest Airlines.