Union garbage haulers for Waste Management in King and Snohomish counties say they are prepared to return to work unconditionally Friday morning at midnight in order to prevent a “public health crisis.”

Teamsters Local 174 says the decision was made to prevent a public health crisis and to minimize service disruptions, according to a statement released Thursday afternoon.

The union says it expects about 700 area workers to return to shifts in order to make up for lost time on collection routes. Seattle-area garbage workers went on strike early Wednesday, claiming Waste Management was refusing to bargain on an expired contract.

Elected leaders in the region urged a quick settlement of the garbage-hauling dispute.

King County Executive Dow Constantine and Seattle Mayor Mike McGinn sent a joint letter to both sides.

“I strongly encourage both sides to return to the bargaining table as soon as possible to work toward a quick and fair resolution to this strike,” Constantine said. “In the meantime, we are taking steps to minimize impacts for residents and making changes at our waste transfer facilities so our workers will not have to cross a picket line to do their jobs.”

Pickets went up at 10:30 a.m. Wednesday at Waste Management facilities, said Union spokesman Michael Gonzales.

Auburn is one of several cities in King County affected by the strike. The strike affects waste pickup for about one million people in King and Snohomish counties. Waste Management picks up garbage in Federal Way, Auburn, Algona, Pacific and much of unincorporated south King County.