Bush administration standards for pollutants like soot are “contrary to law and unsupported by adequately reasoned decisionmaking,” a federal appeals court said Tuesday.

The court ordered the Environmental Protection Agency to reconsider its standards for the pollutants, fine particulates, which are linked to premature death from lung cancer and heart disease and to other health problems including asthma.

When the agency embraced the standards in 2006, its own scientific staff rejected them as too lax. In Tuesday’s ruling, the United States Court of Appeals for the District of Columbia Circuit said the agency “did not adequately explain” why the standards were adequate.

The decision is “a victory for the breathing public,” said Paul Cort, a lawyer with Earthjustice, who argued the case for environmental groups. The legal effort was joined by health organizations and more than a dozen states, including Connecticut, New Jersey and New York.