(CNN) — United Airlines said Wednesday it now requires all passengers to self-certify their health prior to boarding a flight.
The airline is the first major US carrier to require all passengers to complete a health questionnaire to screen for the coronavirus as part of checking in.
The questionnaire asks passengers to certify they have not experienced coronavirus symptoms in the last 14 days nor tested positive for the virus in the past 21 days.
It also requests passengers agree to wear a face mask during the flight, which is an airline policy, but not a federal requirement.
A United Airlines flight attendant, Susannah Carr, testified before the House Transportation Committee on Tuesday that her colleagues have discussed "the fact that passengers don't like to wear the mask, might take it off for a longer period than just to eat or drink. It's definitely an issue that we need to address."
The airline was the first US carrier to require face coverings for flight attendants, and United later followed with passenger mask requirements as of May 4.
But US airlines have been reluctant to make flight attendants responsible for enforcing in-flight coronavirus policies.
United said customers who "are not able to confirm these requirements" -- including the new health standards -- will be "able to reschedule their flight."
There are no current US government or industry-wide requirements for this broad type of health screening.
The airlines have asked the Transportation Security Administration to conduct temperature screening of passengers, but so far the agency has not decided to do so.
Health screening has been conducted by government entities at some US airports, particularly for incoming international passengers.
Frontier Airlines says it takes the temperature of each passenger to check for a fever prior to boarding.