According to documents released last week, the Environmental Protection Agency intended to propose an air quality standard for fine particulate matter of 12 micrograms per cubic meter of air, but that the White House Office of Management and Budget changed the proposal to be in a range between 12 and 13 μg/m3 during interagency review. The current annual primary national ambient air quality standard for fine particulate matter is 15 μg/m3. The less stringent standard would be less costly but carry fewer health benefits. Comments are due August 31, and the final rule is due December 14.