Environmentalists are reiterating their calls for a federal appeals court to force EPA to designate parts of Colorado and Ohio as "nonattainment" for federal sulfur dioxide (SO2) standards, which would trigger strict requirements for the states to impose emissions control requirements on sources of SO2 within their control.

President Donald Trump is signaling support for pending EPA plans to allow year-round sales of ethanol fuel blends up to 15 percent (E15), prompting a warning from ethanol critics including the petroleum sector that the agency lacks the Clean Air Act authority for such a waiver.

Top House Republicans are expressing confidence about enacting a nationwide high-octane fuel standard as part of a broader package to "reform" or scale back the renewable fuel standard (RFS), arguing the move could satisfy a range of fuel stakeholders while also giving automakers a relatively cheap compliance option for fuel economy limits.

The United Nations' (UN) International Maritime Organization (IMO) that sets shipping emissions standards for member countries including the United States has agreed to cut shipping greenhouse gases (GHGs) by at least 50 percent from 2008 levels by 2050, over the objection of President Donald Trump's administration that largely opposes GHG rules.

Three former Democratic members of the Federal Energy Regulatory Commission (FERC) are disputing EPA Administrator Scott Pruitt's reasoning for seeking to repeal the Obama-era Clean Power Plan (CPP) to cut utility greenhouse gas emissions, saying that contrary to what the administrator says, the rule does not step on FERC's authority.

The trade association Global Automakers, which represents mostly foreign manufacturers, is said to be discussing a proposal, potentially along with other automakers, for retaining the goals of EPA's current greenhouse gas standards for light-duty vehicles, while adding more compliance flexibility that includes expanded use of "off-cycle" and alternative vehicle credits.

EPA's controversial proposal to scrap production limits on "glider" trucks that do not meet modern emissions standards has been languishing for months, amid prior speculation that the agency was weighing a compromise plan though it now appears to be simply trying to shore up the proposal's legal basis before finalizing it.

Duke Energy is touting its plan to launch a third-party mitigation project -- required by an enforcement settlement with EPA -- that provides rebates to help consumers swap out old wood stoves for clean ones, renewing doubts over Attorney General Jeff Sessions' policy that seeks to block payments to third parties under such settlements, including a similar wood stove mitigation deal with Harley-Davidson that the government is seeking to drop.

EPA's Office of Inspector General (OIG) is launching an audit into EPA's oversight of smokestack emissions testing and reporting, with an initial focus on the agency's Region 10 covering the Pacific Northwest.

Samantha Dravis, the head of EPA's policy office and a long-time confidant of Administrator Scott Pruitt, has resigned from the agency just as a swirl of negative headlines broke about Pruitt's alleged ethical lapses regarding travel, living arrangements and hiring practices.

EPA's Environmental Appeals Board (EAB) has approved EPA Region 5's motion for a voluntary remand of an air permit the region issued for incinerators owned by waste disposal firm Veolia ES Technical Solutions, LLC, ending a case in which the company had claimed the agency used a permit to "rewrite" its waste combustor air toxics rule.

White House regulatory chief Neomi Rao says her staff is working with EPA on developing a policy on the use of scientific data that underlies its rules, suggesting that the agency may take a softer approach than Administrator Scott Pruitt had signaled when he said he would require the agency to rely only on publicly available data to justify its rules.