INVERNESS PARK, Calif. >> Pacific Gas and Electric’s campaign to introduce wireless smart meters in Northern California is facing fierce opposition from an eclectic mix of Tea Party conservatives and left-leaning individualists who say the meters threaten their liberties and their health.

In the San Francisco Bay Area, “Stop Smart Meters” signs and bumper stickers have been multiplying on front lawns and cars. Four protesters have been arrested for blocking trucks seeking to deliver the meters.

Since 2006, PG&E has installed more than 7 million of the devices, which transmit real-time data on customers’ use of electricity.

But in Santa Cruz County, south of San Jose, the Board of Supervisors recently extended a yearlong moratorium on installations. Officials in Marin County, north of San Francisco, approved a ban this month on meters in unincorporated, largely rural areas, where about a quarter of its population lives.

The meters are a crucial building block for what the Obama administration and the industry envision as an efficient “green grid.” The goals are to help utilities allocate power more smoothly and to give people more information on how they consume energy and incentives to use less.

At first, the backlash against PG&E focused on the notion that the meters were giving artificially high readings, but that died down after studies confirmed their overall accuracy.

The new wave of protests comes from conservatives and individualists who view the monitoring of home appliances as a breach of privacy, as well as from a cadre of environmental health campaigners who see the meters’ radio-frequency radiation — like emissions from cell phones and other common devices — as a health threat.

Hypervigilance on health questions has long been typical of Bay Area residents; some local schools ban cupcakes or other sugared treats for classroom birthday celebrations in favor of more nutritious treats like crunchy seaweed snacks, for example.

The health concerns about the smart meters focus on the phenomenon known as “electromagnetic hypersensitivity,” or EHS, in which people claim that radiation from cell phones, WiFi systems or smart meters causes them to suffer dizziness, fatigue, headaches, sleeplessness or heart palpitations. (At a recent Public Utilities Commission hearing on smart meters, an audience member requested that all cell phones be turned off as a gesture to the electrosensitive people in the audience.)

The two most recent government reviews of available research found no link between health problems and common levels of electromagnetic radiation. Both reports indicated that more research would be welcome; on that basis, opponents say the meters should not be installed until they are proved safe.

Although there is scientific data on the health concerns, the privacy worries can be answered only by assurances from the utility. And the groups most concerned about privacy — like the local Tea Party affiliate, the North Bay Patriots — tend to have little faith in corporate assurances.

At a meeting of the North Bay Patriots this month, Jed Gladstein, a 64-year-old lawyer, called the devices “the sharp end of a very long spear pointed at your freedoms.” Others have raised concern about how the utility would use the information about individuals’ home appliance use.

David K. Owens, the executive vice president for business operations at the Edison Electric Institute, the national association of utilities, has tried to allay such concerns. “We’ve always gotten information about customers’ usage and always kept it confidential,” he said, adding, “We’re going to honor their privacy.”

Protests related to health and privacy concerns have also blossomed elsewhere in the country. In Maine, for example, residents have waged e-mail campaigns and some towns have adopted moratoriums on installations.

In Northern California, the visceral reaction against the meters and the instant bonding of “electromagnetically sensitive” people also reflects the reality that green solutions often involve new technologies. From genetically engineered seeds to solar tower arrays in the desert, those technologies elicit distrust in many quarters here.

“It’s not all about saving money — it’s about control,” said Deborah Tavares, 61, a Republican who was arrested this month with other protesters who blocked the driveway of the dispatch center for meter installation trucks in Rohnert Park, south of Santa Rosa.

Her words echoed those of a staunch Democrat who was arrested in nearby Marin County. “It’s another example of corporate control if they are going to roll over our concerns and not listen to us,” said Katharina Sandizell, 41, who helped block installation trucks here in Inverness Park, a hamlet in the environmentally sensitive precincts of Marin County.

As she chatted on a recent day outside a deli on Sir Francis Drake Boulevard, she and fellow protesters held up signs urging passing drivers to “Refuse PG&E.” Perhaps one driver in 10 honked in support, and one woman pulled over to ask how she could get a lawn sign.

Heeding his constituents’ worries about electromagnetic frequencies, a state assemblyman from Marin County, Jared Huffman, has introduced a bill to require the utility to offer customers the option of hard-wired smart meters. “It’s not that I personally believe that smart meters are harmful,” he said in an interview. “I have one in my house.”

“But it’s reasonable to let people opt out of a wireless device,” he said. “There’s fiber optic, phone line, Internet — there’s any number of ways to get this information.”

Jeff Smith, a spokesman for PG&E, said the utility was considering the hard-wire option. “We do understand that some of our customers have concerns,” he said, even though “the evidence shows overwhelmingly” that no link to health effects has been established.

The two most recent government reviews of the relevant health studies on electromagnetic hypersensitivity were conducted by health experts drafted by the Maine Public Utilities Commission and by a California technical panel. Neither found a link between such health problems and levels of radiation associated with a smart meter.

“The majority of studies indicated that people who described themselves as suffering from such sensitivity could not detect whether they were being exposed to an electromagnetic field in experiments any more accurately than non-EHS individuals,” said the Maine review, issued in November.

The largest relevant scientific study, a 10-year, $24 million effort dealing with exposure to cell phone radio-frequency radiation, showed a correlation between heavy cell phone use and an increase in brain cancer rates but did not establish that one caused the other. Both sides in the debate quote the study to bolster their arguments.

“No one who’s been affected by this is willing to wait for the science to catch up with the causal link,” said Elisa Baker-Cook, 40, a former journalist from Scarborough, Maine, who is leading protests against Central Maine Power’s meters. “When someone is sensitive to wireless, they don’t need a causal link. Our bodies’ reaction is the causal link, and we learn to trust that.”

Dave DeSante, 68, an ornithologist who lives in Marin County, has tried for six weeks to get PG&E to remove a smart meter in his home. His son, Forest, a college student whose skull was severely damaged two years ago, now has a network of titanium filigree in his forehead.

Forest DeSante, who had been unaware that a smart meter was installed in the house just after Thanksgiving, began having severe headaches when he sat near it, his father said. The headaches let up only when he left the house, he added.

Dave DeSante said that he had made several calls to PG&E and that the utility promised to look into the problem but has not yet done so.

“The concerns and opposition to this are not going away,” said Huffman, the assemblyman from Marin County. “If anything, they’re growing.”

© 2011 The New York Times Company