Philadelphia declared a public health emergency yesterday, an administrative action that mainly gives hospital emergency rooms more flexibility in dealing with increasing numbers of swine flu patients, most of whom are not seriously ill.

Visits to ERs in the city are up about 25 percent over this time last year, officials said, a statistic that combines far greater increases at pediatric hospitals with lesser increases at acute-care facilities.

Mayor Nutter's declaration, a week after President Obama made a similar announcement for the nation, allows city hospitals to use alternative spaces, permits easier transfer of patients between facilities, and waives certain requirements on bed limits and length of stay.

"I cannot stress this enough - if you have mild flu symptoms, please do not go to the emergency room," Health Commissioner Donald Schwarz, who made the recommendation to Nutter, said in a statement. "If medical staff and hospital staff have to deal with nonemergency cases, this diverts resources away from where they are desperately needed."

A spokeswoman for the New Jersey Department of Health and Senior Services said the state had no plans to declare an emergency.

Gov. Rendell said Pennsylvania also had the authority to handle the illness so far.

The state's medical board is expanding the scope of care that can be handled by physician assistants, Rendell said at a news conference.

And the state has given waivers to hospitals to more quickly set up alternative sites to handle a surge of patients, he said, citing the extra ER that Children's Hospital of Philadelphia set up in its atrium a week ago.

Most cases of swine flu have been among children and young adults.

"I have almost no chance of contracting it," Rendell said. "A, because I'm older, and B, I have shaken about 180,000 hands in the last 10 years, so I'm immune to any communicable disease."

"As I tell my staff," he said, "if an alien virus came to Earth and killed everyone, it would be me and the cockroaches surviving."

For mortals at risk from the flu, immunization is recommended and hard to find. A few health departments have enough to schedule public flu clinics for priority groups. See http://go.philly.com/swineflu