Nearly 8,000 nurses and health workers in the Seattle area plan to walk off the job Tuesday morning as part of a three-day strike at Swedish Health Services.

It will affect all five Swedish hospitals, and some procedures have been delayed due to staffing concerns. Emergency rooms in Ballard and Redmond will close on Monday evening and are expected to reopen on Friday.

Swedish has flown in thousands of replacement nurses and staff to fill in this week.

The strike comes after months of failed negotiations and a last-minute delay this month, as Swedish and union members tried to reach a deal to avert the strike.

Organizers say they are striking not only over pay and benefits, but also dangerously low staffing levels.

Terry Thompson, a charge nurse, has worked at Swedish for more than three decades and says people used to eagerly wait for a job to open up.

“And there weren’t any,” Thompson said. “Now there are 600 nursing positions they can’t even fill.”

Thompson attributes the staffing issues to inadequate working conditions where everyone — from nurses to the workers responsible for cleaning hospital rooms — is overstretched.

“You go to look for help, there is literally no one at the desk because everyone is already with a patient,” she said.

Many in the union believe the issues with staffing emerged when Swedish became an affiliate of Providence Health & Services in 2012.

Swedish management rejects this characterization and says the health provider has a vacancy rate of about 11 percent, which is a symptom of a national nursing shortage, not poor working conditions.

“We will successfully make sure that our patients are well taken care of, that our community is supported and feels safe and we are 100 percent committed to our caregivers,” Swedish CEO Dr. Guy Hudson said earlier this month.

Hudson says the temp workers coming in are qualified and are only supplementing existing teams.

But those who study hospital strikes say it could be hard to take care of patients during such a tumultuous moment.

“I would have grave concerns about the care that could be delivered in that hospital during a strike,” said Rebecca Givan, an associate professor in the School of Management and Labor Relations at Rutgers University, who studies hospital strikes.

“In fact, there’s research that’s very clear that with these replacement workers the quality of patient care will go down,” Givan said. “They are not familiar with the workplace or the local patient population."

Givan said a strike of this magnitude will hurt Swedish’s finances and reputation.

“It will create serious concerns among patients and the local community as they rightly question what kind of care is being provided at a hospital where all of the workers have gone on strike because of concerns about management’s commitment to patient care,” Givan said.

Officials with Swedish say they don't expect operations to be affected significantly by the strike.