Mayor Michael Nutter has signed into law a measure requiring multifamily dwelling owners to use sealed smoke alarms with long-lasting batteries. 

The bill mandates the use of sealed smoke detectors with 10-year batteries to prevent removal of batteries or the possibility of forgetting to replace a dead battery.

Proponents of the measure say it will save lives.

"In April alone, Philadelphia lost three children two mothers, a grandfather, a grandmother in three separate household fires," said Councilman Curtis Jones, sponsor of the measure. "In all three of those occasions, there wasn't an operable smoke alarm."

Nutter says sealed smoke alarms are key to keeping people safe.

"In 2011, 34 percent of the homes in Philadelphia had no batteries in their smoke alarms and 22 percent had dead batteries," he said.

The requirement is for single and two family dwellings and will take effect January 9th 2013.