The Environmental Protection Agency has proposed to extend the deadline for cement manufacturers to comply with federal air pollution standards.
The extension could impact some local companies.
The EPA proposal would extend the deadline by two years, giving cement manufacturers until September 2015 to comply with the standards.
It would also change how kilns monitor particle pollution, and some cement air pollution limits. Restrictions on mercury and hydrochloric acid would stay the same.
There are a number of cement manufacturers in the St. Louis region. The largest cement plant in the country, owned by Holcim, is located Ste. Genevieve.