By Hadas Kuznits

PHILADELPHIA (CBS) — New smoke detector laws went into effect today in the city of Philadelphia.

Philadelphia fire commissioner Lloyd Ayers says smoke detectors that require a battery change once a year are now illegal in your home, even if they still work.

“So all of our residents will now have to have 10-year, non-removable battery, lithium-powered smoke alarms,” he says.

And Ayers says smoke alarms that don’t require a battery change for a decade are sure to save lives.

“Many of the house fires where we have fatalities, we find that they have smoke alarms that don’t work — dead or missing batteries, (or) located in the wrong area.”

Ayers say the fire department is working with hardware stores on their inventories, as some of the outdated smoke detectors may still be temporarily available.  He says the ones you want are the ten-year, non-removable, lithium-battery smoke detectors.

Since 1988, Philadelphia law has required hard-wired smoke detectors in all new residential construction.