My landlord (I rent in an apartment complex in the Bay Area) wants to prohibit smoking – not just in my apartment, but in the entire rental property. Is this legal?
Yes, it's legal. As of January, 2012 California landlords have the right to restrict or even completely ban smoking on all or parts of the rental premises, common areas and individual units included. (CC § 1947.5.) If your rental agreement does not currently prohibit smoking, your landlord can give you a 30-day notice of change of terms of tenancy covering anti-smoking rules. The landlord's new smoking restrictions will not affect you if you have a lease unless your lease is renegotiated mid-lease or it is renewed at the end.
And if your apartment complex includes a children's play area or a "tot lot" sandbox area, your landlord must prohibit smoking within 25 feet under state law. (H&S § 104495.)
For future reference, California's smoking law requires leases entered into on or after January, 2012 to include the landlord's smoking policy, if the landlord has one.
If you want to know about other state law restrictions, such as workplace smoking laws in California, check the Employment Section of the Nolo site, which includes state-specific rules on workplace smoking laws.
Tenants who live outside of California should check their state or local laws for smoking restrictions. One place to start is the website of Americans for Nonsmokers' Rights. This site includes a variety of resources for landlords and tenants.