The TXI Oro Grande cement plant near Victorville will pay $394,000 and shut down seven 50-year-old kilns as part of a proposed settlement this week with the U.S. Environmental Protection Agency, which had sued the company for alleged violations of federal Clean Air Act.

The plant already is testing a new $385m, state-of-the art kiln to replace the old kilns, said David Kim, a San Francisco-based attorney for the EPA. Kilns are like large ovens in which raw materials are heated for the cement-making process.

The improvements are expected to slash nitrogen-oxide pollution from the plant by 1,500 tons a year. A 2007 report by the California Air Resources Board listed the plant’s annual output at 4,111 tons. Nitrogen oxide mixes with other pollutants to create lung-irritating ozone gas. Ozone can cause headaches and nausea and aggravate respiratory illnesses, including emphysema and asthma.

Plant Manager Gordon Johnson could not be reached for comment.

The EPA issued a statement Wednesday that said the plant repeatedly exceeded kiln-temperature or nitrogen-oxide limits. Plant operators also did not complete required inspections and particle-pollution tests, the statement said.

The settlement will be subject to a 30-day comment period before being made final in federal court. The comment procedure will be outlined in a yet-to-be published notice in the Federal Register.