WASHINGTON  Burning fossil fuels costs the United States about $120 billion a year in health costs, mostly because of thousands of premature deaths from air pollution, the National Academy of Sciences reported in a study issued Monday.

The damages are caused almost equally by coal and oil, according to the study, which was ordered by Congress. The study set out to measure the costs not incorporated into the price of a kilowatt-hour or a gallon of gasoline or diesel fuel.

The estimates by the academy do not include damages from global warming, which has been linked to the gases produced by burning fossil fuels. The authors said the extent of such damage, and the timing, were too uncertain to estimate.

Nor did the study measure damage from burning oil for trains, ships and planes. And it did not include the environmental damage from coal mining or the pollution of rivers with chemicals that were filtered from coal plant smokestacks to keep the air clean.