A cement plant in Carroll County that is one of the state’s top mercury polluters has agreed to slash its emissions of that highly toxic metal and of harmful particle pollution as well, state officials announced yesterday.

Lehigh Cement Co.’s Union Bridge plant has voluntarily agreed to reduce its mercury emissions 80 per cent by March 2012, according to the Maryland Department of the Environment. That would be a year earlier than the plant would have had to make reductions under new federal pollution regulations proposed earlier this year.

Ingesting mercury can harm the brain, nervous system and other organs, and it can build up in fish. Maryland warns women and children to limit their consumption of certain fish because they may have low levels of methylmercury, one form of the toxic metal.

Mercury releases from cement kilns are not currently regulated, but the Environmental Protection Agency in April proposed industrywide limits that would take effect in March 2013.

Cement industry officials had complained that EPA’s proposal to slash mercury emissions was "excessively stringent" and could force U.S. plants to shut down. But Kent Martin, the Lehigh plant manager, said his company believes the reductions can be achieved cost-effectively at the Union Bridge plant. He expects to begin testing later this month on how to keep mercury from escaping into the air, he said, by injecting carbon into the cement manufacturing process. Those tests should lead to an 80 per cent reduction by 2012, he said.

Meanwhile, the company has vowed to reduce mercury emissions by 30 per cent to 40 per cent this year, using another control technique. In return, the state will permit the cement plant to burn either dry fertilizer or pelletised sewage sludge as long as it takes steps to ensure that the new fuel does not increase mercury emissions.

Environmentalists, who had urged state and federal action to reduce mercury pollution from cement plants, praised the agreement.

Lehigh also agreed to pay a US$202,500 penalty to settle allegations made by the state that the plant violated its limits on particle air pollution in 2007. As part of a consent decree entered in Baltimore City Circuit Court, the company pledged to test and repair its particle pollution controls. Particle pollution can aggravate asthma and bronchitis, cause heart and lung problems and even premature death.