WASHINGTON — Construction-related fumes leaked into a Federal Aviation Administration facility in Leesburg, Virginia, Monday night, leading to some flight delays at the three D.C.-area airports on Monday and very early Tuesday. FAA employees were allowed to return to the Washington Center in Leesburg shortly around 9 p.m. after they were evacuated around 6:40 p.m. Fumes from construction work permeated the control room, forcing employees at the Washington Center to evacuate, according to FAA spokeswoman Kathleen Bergen. But operations did not immediately resume until around 9:30 p.m. Flights were back to normal by 7:30 a.m. Tuesday, although officials had warned of residual delays. In one case, Delta Air Lines has issued a travel waiver for July 10–11 due to the disruption.

Due to Washington Air Traffic Control situation, we’ve issued a travel waiver for July 10-11. For more info: https://t.co/jENbgPSN5n

— Delta (@Delta) July 11, 2017

The FAA put measures in place to “slow flights” into Reagan National, Dulles International and BWI Marshall airports, Bergen said. The facility stopped accepting new flights and handed off flights currently in the air to other air traffic control facilities during the incident, she added. Fire and rescue crews responded to a report of a “general odor” that was “mildly irritating” to the eyes and throat, said Assistant Chief Matthew Tobia with Loudoun County Fire and Rescue. One person was transported to a hospital with a non-life-threatening condition at her request as a precaution, Tobia said. Crews worked to fully ventilate the building, and, Tobia added, “have found nothing that would cause any health effects.” The facility handles high-altitude flights over the D.C. area. WTOP’s Teta Alim contributed to this report.