The Environmental Protection Agency has finalised rules to curb pollution for cement plants, agreeing to give industry additional time for compliance and easing some emissions limits from earlier proposals.

Cement kilns will face strict limits on mercury, acid gases and fine particulate matter, but plants will not have to comply with the new limits until September 2015, two years after they were originally set to take place.

There are fewer than 115 cement plants in the United States, but they account for 7 percent of the mercury released into the air from stationary sources.

The Portland Cement Association welcomed the revisions. “EPA’s revised rule strikes the right balance in establishing compliance limits that, while still extremely challenging, are now realistic and achievable,” said Greg Scott, president of the industry group.