Contact tracers are being asked to overtime voluntarily, according to internal emails obtained by WNYC.

"By the end of the day, I'm exhausted, so putting in one hour of overtime is all I've been able to handle so far," said one worker named Maxine, who was not authorized to speak publicly.

Mayor de Blasio has pledged to hire more tracers, but he has not said how many—or how quickly they can be deployed. A spokesman for the city said nearly 90 percent of cases completing interviews are done within 48 hours, and 1 percent of tracers have used overtime.