- The U.S. Environmental Protection Agency (EPA) has issued a proposed decision to maintain current standards on sulfur oxides, a typical coal plant pollutant. The decision is part of a range of regulatory reviews performed by the Trump Administration, but would keep in place a limit developed under President Obama.
- The current primary standard is set at a level of 75 parts per billion (ppb), as the 99th percentile of daily maximum 1-hour SO2 concentrations, averaged over three years.
- While the proposal would keep the limits in place, the review of the primary National Ambient Air Quality Standards (NAAQS) for SO2 asks for comment on how the calculation is done and "whether
there are appropriate alternative approaches for the averaging time or statistical form."
Earlier this month EPA Administrator Scott Pruitt issued a memo outlining changes to the NAAQS review process, highlighting a "back to basics" approach. For the agency, that will mean reviews "in a manner consistent with cooperative federalism and the rule of law."
Critics, however, say it would allow the agency to diminish the input of human health science in reviewing the standards.
In the first proposed NAAQS decision since that memo two weeks ago, the EPA is calling for the current limits to remain in place — while requesting input on potential changes.
The EPA's proposed decision asks for comment on the four "basic elements" of the current NAAQS: indicator; averaging time; level; and form. EPA is asking in particular "whether there are appropriate alternative approaches for the averaging time or statistical form that provide comparable public health protection, and the rationale upon which such views are based."
Comments on the proposal are due within 45 days of the draft being published in the Federal Register.
The NAAQS standards were first enacted in 1990 and must be reviewed every five years. In 2015, the EPA set the standard for ground-level ozone at 70 ppb.