MARTINEZ -- Smoking tobacco and medical marijuana in new multiunit housing complexes in unincorporated Contra Costa, even in the privacy of a resident's own dwelling, will be banned because of a new county ordinance.

Contra Costa supervisors voted 4-1 Tuesday to adopt the new regulations, joining four other cities in the county with similar secondhand-smoke restrictions.

For new and existing multiunit housing, residents will no longer be able to smoke on balconies, patios, decks or in carports. The new ordinance would also make smoking in a nonsmoking area of the housing complex a lease violation, and give landlords the right to evict a tenant after three violations.

"We're trying to strike a balance and protect public health. Ultimately, it is beyond someone's control if a neighbor is smoking and it affects their health," Supervisor John Gioia said. "We're protecting people from risks that may be involuntary."

Drifting smoke complaints increased to county health services staff members by more than 50 percent since January 2009 in Contra Costa's more than 20,000 rental units, the department said.

Supervisors delayed their vote on the ordinance while attorneys debated how medical-marijuana use should apply to the ordinance. In the end, supervisors voted to treat tobacco and medical marijuana smoke equally.

Supervisor Mary Piepho voted against the measure despite being a "victim of secondhand smoke" herself, calling the ordinance too broad. Piepho said restricting 100 percent of new multiunit residences -- defined as a housing complex with four or more units -- was "far-reaching into property rights and privileges."

County motels and hotels must have at least 80 percent of their rooms smoke-free. The 20 percent of smoking rooms must be separated from the nonsmoking rooms.

"When dealing with this, the health effects on other people living in these units is of paramount importance," Supervisor Susan Bonilla said, adding that it supersedes the idea of personal rights.

Most of the rules go into effect Jan. 1.

Contact Matthias Gafni at 925-952-5026.