(By Justin Moresco) - Businesses in the San Francisco Bay Area could face the state’s first tax on greenhouse gas emissions if a proposal by the region’s air quality agency passes in May. But the fee is so low it is unlikely to spur a significant reduction in emissions or stimulate technological innovation.

Refineries, power plants, landfill sites, laundrymats, and other businesses that are “combustion sources” would pay an annual tax of 4.2 cents per equivalent metric ton of carbon dioxide. The proposal was first made public last week by the Bay Area Air Quality Management District, the government agency that regulates sources of air pollution within the nine-county region.

“This is largely an effort to recover the costs for our climate protection programs,” said agency spokeswoman Karen Schkolnick.

The agency hopes to generate about $1 million a year from the tax to cover its emissions monitoring program, which includes about 10,000 businesses.

The largest emitter in the Bay Area, the Shell oil refinery in Martinez, would pay $186,000 for its 4.4 million tons per year. The fiftieth largest emitter, a paper packaging maker, would pay just under $2,000.

Ms. Schkolnick said the agency also hopes the tax would help persuade business owners to reduce emissions and that giving people accurate information about emissions was a necessary first step.

But Michael Carboy, who covers clean technology for Signal Hill Capital Group, said the tax was too low to expect any change in emissions or to stimulate innovation.

“This isn’t meaningful. It is a nuisance tax,” he said.

Mr. Carboy said that the Stern Review, a prominent study on the economics of climate change done by the British Government, found that carbon dioxide would have to be priced at about $30 per ton to significantly reduce the climate change risk.

Carbon tax proponents and environmental groups were supportive of the proposal. Dan Rosenblum, co-founder of the Carbon Tax Center in New York, wrote on the nonprofit’s web site that while the fee is small, imposing it “would lay a foundation for substantial carbon taxes in the future.”

But Tupper Hull, a spokesman for the Western States Petroleum Association, said the tax would raise costs for consumers and possibly hurt efforts for climate change programs by creating a patchwork of policies across the state.

“We will have the greatest chance of success in meeting climate change goals if we have the broadest possible programs in place,” he said.

The carbon tax proposal will begin being debated at a public hearing at the end of the month. If passed in May by the board of directors, it will go into effect in July.