Dropping your beer on New Year’s Eve may have helped your hangover, but starting this month beer spills could be more than a headache for Colorado’s two biggest brewers, Anheuser-Busch InBev SA/NV and MillerCoors LLC.

Colorado Air Quality Control Commission air pollution rules kick in Jan. 14, and target spilled beer—typically from container breakage and other production losses—that creates ozone pollution when ethyl alcohol evaporates.

The Anheuser-Busch brewery in Fort Collins, and the MillerCoors brewhouse in Golden are the only facilities above the threshold of 100 tons per year of volatile organic compounds emitted, at which point the rules kick in.

The new rules do not affect Colorado’s famous microbrewery sector, with about 350 establishments.

Neither Anheuser-Busch, whose beers range from Budweiser to Busch to Goose Island IPA; nor MillerCoors, makers of beers from Coors to Miller Lite to Grolsch, immediately responded to requests for comment.

Beer Fouls the Air

Evaporation of ethyl alcohol is the largest source of emissions of volatile organic compounds at a brewery, Leah Martland, an environmental protection specialist in the Air Pollution Control Division of the Colorado Department of Public Health and Environment, told Bloomberg Environment.

Volatile organic compounds also form when beer bottles, cans, and other containers are filled, she said.

The compounds contribute to the formation of ozone. Breathing ozone can cause health problems, especially for children, the elderly, and those who experience asthma. The Denver metro Front Range area currently violates federal air quality standards for ozone.

The rules place limits on allowable breakage during the packaging process. They focus on reasonably available control technology requirements for the brewers to be included in Colorado’s state plan to meet the ozone requirements.

The rules also include a section addressing a wood furniture maker, Elkay Manufacturing Co. in Aurora, as a major source of volatile organic compounds.