U.S. farms cost the economy more in health and environmental damage than they contribute to the economy, according to a recent study in the Publication of the National Academy of the Sciences.

For 20 economic sectors, the study compares the cost of premature deaths from particulate air pollution to the value added to the economy. Farms performed worst, driven down by animal agriculture.

“At the margin, we’re seeing that the damages from air pollution provided by farms are larger than the marginal value that the farms provide in economic terms,” said co-author Inês M.L. Azevedo, an associate professor in Stanford University’s Department of Energy Resources Engineering.

The study, conducted with researchers from Carnegie Mellon University, focuses on particulate pollution, including PM 2.5, which the EPA has identified as the cause of 90 percent of the 100,000 annual premature deaths in the U.S. from air pollution.