Mike Leavitt, administrator at the Environmental Protection Agency, said this week the EPA will rescind a ruling from 2000 that would force power plants to reduce mercury emissions, and instead will debate various methods of reducing this health hazard from the air. Whatever the merits of the alternatives, this new delay – in a line of delays from an administration too often hostile to environmental protection – looks exactly like a decision to put the operation of outdated power plants ahead of the health of the public.

Mr. Leavitt described his plans as a Dec. 15 deadline approached for his agency to submit rules on how the coal- and oil-fired power plants were to meet standards for use of what is known as “maximum achievable control technology” standards. Instead of rules to stop these plants from reducing the 48 tons of mercury they emit annually, the administration now says the need for the rules is just a misunderstanding.

According to news reports, it argues the Clinton administration misread the Clean Air Act that would require this technology. Instead, a more “flexible” plan is to reduce emissions, through a program which would set an overall cap on mercury emissions and allow plants to trade rights (or allowances) for that level of emissions. Called cap-and-trade programs, the idea has been used effectively to reduce pollutants such as sulfur dioxide and to lower the lead content of leaded gasoline.

But to make such a program more than an excuse to pollute, the EPA must demonstrate that it can be trusted to set tough caps (presumably there would be several, spaced five or six years apart) and ensure the trading program leads to substantial reductions for all plants. Cap-and-trade programs come with a variety of methods, some with the government holding the right to trade allowances, others allowing allowances to be sold among mercury emitters, with or without caps on the price of the allowance. Still others would cap and reduce emissions for individual plants, lowering the cap annually.

The mechanisms that operate the cap-and-trade system are less important than the intent of the operators. Their intent should be to dramatically lower mercury emissions, which especially affect children and can lead to neurological disorders.

The administration, understandably, has not earned much trust among environmentalists for its air-quality policies, including others related to power plants. The health risks associated with mercury are not in doubt and the need to reduce emissions has been known for years. All of which makes this latest announcement from the EPA difficult to accept, providing yet another reason for Congress to insist that the agency stop surrendering its mission to protect the environment – and the children who live in it.