Airports serving Washington, D.C., Baltimore and some cities in Virginia briefly halted all flights Friday evening because of what federal authorities said was a strong chemical smell at the flight center that controls traffic into the airports. According to a spokesperson with the Department of Transportation, the Federal Aviation Administration temporarily stopped traffic at at Ronald Reagan Washington National Airport, Washington Dulles International Airport, Baltimore-Washington International Airport, Charlottesville–Albemarle Airport and Richmond International Airport because of a chemical odor at the Potomac TRACON. FAA spokeswoman Kristen Alsop said Friday that controllers were coming back to work and normal flight operations should return to normal soon.