This new law expands Santa Monica's smoking ban. It's already against the law there to smoke in common areas, such as a walkway or a courtyard.
The city wants to protect people living in multi-residential properties from second-hand smoke.
Landlords and homeowners associations are now required to post signs notifying residents of the new ordinance.
According to the Centers for Disease Control and Prevention, smoking kills 1,000 Americans a day. It is the number one preventable cause of death in the United States.
Some residents applaud the city's tougher smoking law.
"I don't think anyone should smoke. I know it's a habit, people get into it, but I think it helps detour people from even thinking about it if they can't do it at home, at work or at a restaurant. So I honestly think it's good for them and I don't like cigarette smoke so it's good for me," said resident Elaine Keller.
Santa Monica residents caught breaking the new law will have to pay a $100 fine for the first offense. The fine will double if smokers are caught a second time.
Despite smoking bans and tobacco taxes, the smoking rate nationwide is holding steady at one in five Americans-- that's about 46 million adults.
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