The head of Pennsylvania's prison system said Thursday it is costing the state about $15 million to implement new procedures to combat drug smuggling believed to have caused dozens of staff to become sick in recent weeks.

Corrections Secretary John Wetzel said the 25 prisons are on track to resume normal operations next week.

About 50 guards and other employees have reported symptoms since the start of August that are thought to have been caused by exposure to a clear, odorless substance known as synthetic marijuana, or K-2.

Wetzel said attorney-client visits have resumed, and all visits are expected to be allowed starting Monday. The weeklong system-wide lockdown should be over early next week as well.

The prisons are expanding the use of body scanners and drone detection, and adding staff to visiting rooms.

Wetzel said about 80 percent of the department's workers have been trained on the use of protective equipment, and by the end of the day Friday all prisons should have established hazardous materials teams.

Under an emergency procurement process, the state will be sending inmate mail to be processed outside of prisons, but legal mail will be copied by staff in the presence of inmates.

The new address for non-legal mail has been posted online .

"Any time you do locks and any time you stop visits, stop mail, that's a significantly negative impact on inmates and their family members," Wetzel said.

The cluster of illnesses has been tough on staff, he said, adding to what is "already a difficult job."

Visiting room staff is being doubled and there is a 90-day ban on vending machines and photos.

The prisons chief said officials did not want to take more drastic steps, such as banning contact visits for higher risk inmates or limiting incoming mail to postcards.

"We wanted to still be able to maintain that kind of quality interaction with positive forces from the community, while at the same time improving security," he said.