Washington ? Factories that convert corn into the gasoline additive ethanol are releasing carbon monoxide, methanol and some carcinogens at levels “many times greater” than they promised, the government says.

In an April 24 letter to the industry’s trade group, the Environmental Protection Agency said the problem was common to “most, if not all, ethanol facilities.”

Officials in EPA’s Chicago office, which oversees nearly half the industry’s plants, are planning a meeting with company officials in five states to insist on changes to reduce the emissions.

“So far they’ve been quite amenable. They’re coming in. They’re aware of the issues,” said Cynthia King, an EPA attorney.

The government’s crackdown comes while the ethanol industry presses to significantly expand production as many states phase out another widely used fuel additive, MTBE, because it is polluting water supplies. Last week the Senate passed legislation at the behest of farm groups that would more than double ethanol use by 2010.

“One of the benefits of engaging the industry on this is that they are in a very aggressive growth mode right now,” said George Czerniak, chief of the air enforcement and compliance assurance branch in EPA’s Chicago office.

Volatile organic compounds (VOCs) being released by the ethanol plants include formaldehyde and acetic acid, both carcinogens. Methanol, although not known to cause cancer, also is classified as a hazardous pollutant.

The fumes are produced when fermented corn mash is dried for sale as a supplement for livestock feed. Devices known as thermal oxidizers can be attached to the plants to burn off the dangerous gases.

Recent tests have found VOC emissions ranging from 120 tons a year, for some of the smallest plants, up to 1,000 tons annually, agency officials said. It isn’t known whether the chemicals are hazardous to nearby residents, they said.

When the plants were built, many reported VOC emissions well below 100 tons a year, allowing them to bypass a lengthy and stringent EPA permitting process. Plants with emissions above 100 tons annually are classified as “major sources” of pollution under the Clean Air Act and are more heavily regulated.

States started measuring VOC emissions at ethanol plants about a year ago after complaints of foul odors. One small facility in St. Paul, Minn., had to install $1 million in pollution control equipment to reduce the emissions.