Is there a law in Los Angeles that prevents people in apartment complexes from smoking in common areas

Nope. There is currently no law in California prohibiting smoking in private residences or apartment complexes. California recently passed Senate Bill 332, which expands the availability of smoke-free housing in California by allowing (but not requiring) landlords to prohibit smoking in rental housing units. Effective January 1, 2012, Senate Bill 332 adds Section 1947.5 to the Civil Code. The new law does not force California landlords to prohibit smoking in their buildings, but it gives them the choice to make their properties smoke-free. Nevertheless, all California landlords owe duties to their tenants, including the implied warranty of habitability and the implied covenant of quiet enjoyment. Under California law, all leases have the implied covenant of "quiet enjoyment". (California Civil Code, § 1927). The landlord (and management company) has the duty to preserve the quiet enjoyment of all tenants. (Davis v. Gomez (1989) 207 Cal.App.3d 1401, 1404.) Substantial interference is required to establish a breach of quiet enjoyment. An interference by the landlord "by which the tenant is deprived of the beneficial enjoyment of the premises amounts to a constructive eviction if the tenant so elects and surrenders possession, and the tenant will not be liable for rentals for the portion of the term following his eviction." (Kulawitz v. Pacific Paper Co. (1944) 25 Cal.2d 664, 670.)