Sonoma County supervisors on Tuesday unanimously approved restrictions on e-cigarettes that will mirror those they've passed on traditional tobacco smoking in public.

The new rules, which cover unincorporated areas of the county, are in response to the growing popularity of the nicotine vaporizers and concerns over second-hand exposure to the vapors and the chemicals they contain.

Supervisors said they also are concerned about the rapid increase in the number of youth using e-cigarettes and that it may be a starter product to begin smoking.

The county joins a growing list of counties and municipalities — including Sebastopol, Petaluma and Healdsburg — that have acted to include e-cigarettes in their already established smoke-free laws.

The ordinance covers places of employment, as well as public spaces including dining areas, recreational areas and public events.

No one spoke Tuesday in opposition to the ordinance, which will take effect in late July.