The Environmental Protection Agency is targeting a key ingredient for making pizza and bread in its latest last-minute regulation before President Obama steps down.

The proposed regulation published Wednesday would make the emissions standards for industrial yeast makers much more strict.

The EPA said beer, champagne and wine makers, all of whom use some form of yeast, are safe for now. The real targets are those who produce high levels of hazardous air pollutants. It's not the bread, bagel and pizza makers who are targeted under the rules, but the less than a dozen big plants that produce the yeast needed to produce the valuable bread-based products.

The cost of complying with the upgraded standards could be passed down to consumers. The yeast manufacturers must install a number of new monitoring technologies under the proposal to track the amount of hazardous pollutants that are being emitted to significantly control them.

"The [hazardous pollutant] emitted by nutritional yeast manufacturing facilities is acetaldehyde, a probable carcinogen," the EPA proposal read. "In 2016, there are four nutritional yeast manufacturing facilities that are subject" to national emission standards out of the 11 yeast manufacturers that operate in the country, the EPA said in a separate document.

Despite the 11 companies that produce the single-cell organism, the EPA said the yeast industry is "dominated by three international food conglomerates," which include Associated British Foods, Lallemand Inc. and LeSaffre Yeast Corp.

The agency calculated that the total annualized costs for meeting the proposed emission rules would be $172,000 per year. The estimated per-year compliance costs range from $16,000 to $109,000 per facility, which EPA brushed off as minimal.

"Screening analyses suggest that the [economic] impacts of this action will be minimal, with all entities subject to this action estimated to have cost-to-sales ratios of less than 0.1," EPA said. The agency will hold a public meeting on the proposed regulation Jan. 3, and comments on the regulations are due Feb. 13.

The EPA is issuing the proposed rule because of a lawsuit it lost in federal court brought by the Sierra Club, claiming that the rule from the 1990s needed to be updated under the Clean Air Act.