About 2,000 household cleaning products will be reformulated to reduce smog-forming compounds under a new regulation adopted Thursday in California.

The rule will trigger a new, mandatatory wave of “green” products, including window cleaners, general purpose cleaning sprays, degreasers, oven cleaners, metal polishes, furniture sprays, heavy-duty hand soaps and spot removers.

Household cleaners, which contain highly reactive solvents known as VOCs, or volatile organic compounds, are a substantial source of smog. The new standards will reduce emissions by nearly 7 tons per day, which is the equivalent of removing half a million cars from California’s roads.

Mary Nichols, chairman of the California Air Resources Board, said the new rule, adopted unanimously by the board, will require companies to sell cleaners “that are effective but safe for the environment.”

Manufacturers will spend an estimated $50 million to comply with the requirements, which will be phased in over the next three years, according to an air board report. The cost to consumers will range from “no cost or negligible” for glass cleaners to 44 cents for a heavy-duty hand-cleaning soap, according to a board report.

At a hearing in Sacramento on Thursday, manufacturers of the products told the board that they support the new limits even though they will be difficult to achieve.

They are “very aggressive” and will require “very serious and costly reformulation challenges,” said Joe Yost of the Consumer Specialty Products Assn., a trade group that represents companies that manufacture the products. Still, he told the board, “we support most of the VOC limits.”

The state rule is expected to prompt nationwide reformulation of household cleaning products, since companies say it’s often more cost-effective to redesign all products than produce a separate set for California.

Many household cleaners already comply with the new restrictions, which limit the amount of VOCs in the products based on their category. For example, 69 percent of today's general purpose cleaners meet the new limit. For some products, however, it's a bigger challenge; only 10 percent of glass cleaners and furniture cleaners currently have low enough VOC content to comply.

Since the 1970s, California, facing a severe smog problem, has adopted the world’s most aggressive emission standards for a variety of sources, including cars, trucks, consumer products, paints and factories.

Most of the cleaning products already have faced two other rounds of regulation from the California air board over the past 20 years. The earlier rules already have eliminated nearly half of the VOC emissions from California’s consumer products. But they still emit 245 tons per day, or 12 percent of all the VOCs in the state’s air.

California, along with many other states, faces a federal mandate to reduce ozone, the main ingredient of smog, which aggravates asthma, reduces lung function and has other serious health effects.

Carla Takemoto, manager of the air board’s technical evaluation section, said manufacturers are expected to shift to surfactants to replace the VOCs. Found in soaps and shampoos, surfactants are compounds that reduce surface tension when mixed with water, allowing water to do much of the cleaning without strong solvents. They are large molecules, so they have low volatility and don’t contribute to smog, she said.

“We expect to see increased use of surfactant technologies, which we think is a very viable option,” Takemoto said. “Surfactants tend to be more expensive chemicals than some of the other solvents. But because you use such a small amount of them, it’s still pretty cost-effective to use them.”

For some products, however, surfactants don’t work well. A representative of Stoner Inc., which manufactures a product called Invisible Glass, said surfactants leave streaks and haze on windows.

Meeting the new standards “will not be easy,” but the company supported them, saying they “reflect the state of technology for years to come.” Yost of the industry group said the most challenging limits will be for spray floor cleaners that are used with special, lightweight mops and the heavy-duty hand cleaners.

The companies are struggling to make a spray floor cleaner that can meet the standards without leaving slippery residue left by surfactants, he said.

In the new rule, the board banned alkyphenol surfactants as substitutes for the smog-causing compounds because they are estrogen-like substances that can harm aquatic life when discharged into waterways. Alkyphenols are used in some detergents.

In their staff report, air board officials also expressed concern that some manufacturers of glass and floor cleaners and other products may switch to glycol ethers, which are exempt from the rule. A health study published last month linked glycol ethers to asthma and allergies in children.

But Takemoto said glycol ethers probably won’t be used much because they aren’t very effective cleaners and they evaporate slowly, which leaves a residue. She said the air board will watch over industry to monitor glycol ethers.

"If use were to increase we would again evaluate whether mitigation measures would be necessary," said air board spokesman Dimitri Stanich.

State officials decades ago decided to exempt glycol ethers from state smog rules because they have low volatility and don't contribute much to smog. On the other hand, air-quality officials in the Los Angeles region don't exempt them. As a result, glycol ethers are limited in paints, which are regulated by the Los Angeles board, but not in household cleaners.

Environmental groups said they will work with the air board next year in an attempt to regulate glycol ethers.

Generally, the groups welcomed the smog-reducing restrictions, saying it will have the added benefit of improving indoor air.

“Precedent-setting regulations such as these will supply consumers with the safer products that they deserve and demand,” said Luis Cabrales, deputy director of campaigns at the Coalition for Clean Air.

“Although consumers may have difficulty drawing a connection between household cleaning products and smog…the cumulative use of these products by more than 39 million Californians results in significant emissions,” he said.

Pedro Guzman, a car washer in Los Angeles, told the board on Thursday that he has experienced skin rashes and respiratory problems from his use of window and metal cleaners six days a week. He said he supports the rules because they mean he will face fewer health risks and have a cleaner environment.

The California board must still eliminate more emissions from consumer products by the end of 2013 under its state air plan, which is enforced by the U.S. Environmental Protection Agency. New rules targeting a minimum of four more tons per day are expected to be proposed next year.