"California has now set the bar with the strongest workplace violence regulation in the nation," wrote Castillo in a statement.
Two unions, the California Nurses Association and the Service Employees International Union, have been pushing for more comprehensive protections because of what they see as an alarming rate of health care workplace assaults, such as the 2010 strangling death of a nurse at a state-run psychiatric hospital in Napa.
"Unfortunately, [violence] is sort of a daily occurrence," said Kathy Hughes, a registered nurse and spokesperson for the SEIU Nurse Alliance of California. She said her union formed a campaign and talked to hundreds of health care professionals, many of whom had accepted the idea that assaults happen at work. But "violence shouldn't be part of the job," said Hughes.
The California Nurses Association sponsored the 2014 bill that required the board to adopt the violence prevention rules this year.
National research shows that health care workers are at a "substantially higher" risk of workplace violence than the average worker. In 2013, for example, private-sector hospital workers were five times more likely to take time off from work because of an injury caused by violence than a typical private sector worker.
Workplace safety standards already exist in California, but the Cal/OSHA rules are specifically designed to prevent violence.
"It can't be a cookie-cutter approach," said Hughes, adding that emergency departments and pediatric care units pose different dangers to workers, so safety protocols can't simply be a canned plan found on the Internet.
Both the California Nurses Association and SEIU say they hope the new California standards will become a national model.
Testimony at hearings leading up to the approval of the rules to prevent violence suggest that worker assaults vary in severity.
As a student nurse at a San Francisco hospital, Amy Erb remembered being kicked in the head by an agitated, confused patient with a traumatic brain injury.
Other health care workers told stories about patients throwing lamps, lifting caregivers up by their necks or stuffing dirt into the mouths of their colleagues.
Under the new rules, California employers wouldn't be liable for every act of violence against a worker, such as a mass shooting, but they could be cited by Cal/OSHA for not following protocols, Hughes said. The standard applies to hospital-affiliated facilities and clinics, including home health care settings and drug treatment programs.
Hospitals and physicians were at the table when regulators hammered out the workplace rules. The California Hospital Association didn't provide comment for this story, but it had been opposed to creating new standards when lawmakers looked at the issue in 2014. Hospitals also wanted "workplace violence" to be better defined.
The hospital trade association said several recent trends may contribute to violence at health care facilities. Cuts to mental health care services lead to more psychiatric patients in hospitals. The aging patient population may include more Alzheimer's patients, some with aggressive tendencies. And hospitals caring for current or recently released prisoners face a higher risk of violence.
This story was produced by Kaiser Health News, which publishes California Healthline, an editorially independent service of the California Health Care Foundation.