New Delhi, March 14 -- Four airports serving Washington, D.C., Baltimore and Richmond, Virginia, halted all flights on Friday evening for over an hour because of a strong chemical smell that was impeding air traffic controllers, according to the Federal Aviation Administration.

The ground stop affected Ronald Reagan Washington National Airport, Washington Dulles International Airport, Baltimore-Washington International Airport and Richmond International Airport, FAA Secretary Sean Duffy announced on social media Friday. The declaration caused flight delays to soar to roughly two hours across some of the busiest airports in the country.

Flights began to leave the airports after 7 p.m. ET on Friday, but the ground stop - which prevents pl...