HARRISBURG — The Pennsylvania Corrections Department announced Friday it will screen books donated to state prison inmates for drugs as part of its response to a sharp rise in the number of employees seeking medical care for suspected exposure to synthetic marijuana.

The agency told The Associated Press that outside donation groups will no longer ship books directly to inmates. Instead, they will be examined by drug sniffing dogs at a central location before being handed out to prisoners.

The most commonly requested free book is a dictionary, so the prison system has decided it will provide them to all inmates who ask. They will be purchased with the prisons’ inmate general welfare fund.

After a two-week lockdown that began in late August and changes to mail and visiting procedures, the number of staff seeking emergency room for exposure to synthetic marijuana or other drugs has fallen considerably.

Officials believe smugglers have been soaking the pages of letters and books with synthetic marijuana to get them to inmates without being detected.

Drug finds and positive results in random inmate drug tests are down by about half, and both assaults and drug misconducts have also fallen since new procedures have begun to be implemented.

“Halfway into the full implementation of these protocols, they are making a difference on all levels of risk to staff, inmates and visitors,” Corrections Secretary John Wetzel said in a statement.

Ten thousand pieces of non-legal mail every day now go to a post office box in St. Petersburg, Florida, where a vendor opens, scans and sends them by email to the 25 state prisons. The mail is printed out and inmates are given a copy.

Those mail handling changes have drawn complaints, particularly regarding confidential mail from lawyers. Prison workers open and copy legal mail in the inmate recipient’s presence and give them photocopies. The prison system keeps the original secured for 45 days before destroying it.

The agency says it is considering setting up a secure email system exclusively for legal mail.

Vic Walczak, lawyer for the American Civil Liberties Union of Pennsylvania, said an email system for legal correspondence with inmates is “a long way off and won’t cure the problem.” He said the ACLU continues to work on a legal challenge to the lawyer mail procedure.

Synthetic marijuana, technically synthetic cannabinoids and also called K2, refers to a class of chemicals that trigger responses in the brain receptors that also respond to the active compound in marijuana.

Prison officials say staff emergency room visits for suspected drug exposure fell from 48 in August to eight last month.

For the past two weeks, inmates have purchased about 4,000 e-books under a new policy that expanded the use of e-readers that were formerly restricted to music, games and a form of email. They also can now order regular books through kiosks in state prisons, and prison libraries are expanding.

Facilities that have not had drone detection equipment will be getting it the week of Oct. 29, and new body scanners are being installed in the coming weeks. Ion scanners to check for drugs should be in all prisons sometime next month.

A new policy is being developed on visiting rooms, including the use of vending machines that have been linked to drug smuggling.