The Ozone Transport Commission (OTC) of 12 Northeast and Mid-Atlantic states is shifting its focus on plans for ozone reductions from its traditional targeting of power plant emissions to other ozone sources including natural gas infrastructure, cement manufacturing plants and truck idling in order to meet EPA's stricter ozone limit.

Groups representing dozens of state and local industry sectors are urging EPA to "expeditiously reconsider" the Obama administration's 2015 decision tightening the ozone national ambient air quality standard (NAAQS) from 75 parts per billion (ppb) to 70 ppb, saying implementation of the stricter limit will cause economic harm.

California is threatening to press ahead with its own light-duty vehicle greenhouse gas limits if EPA weakens model year 2021 standards, though automakers seem to be downplaying any MY21 changes as reasonable efforts to "harmonize" EPA's rules with related Department of Transportation fuel economy requirements.

EPA is expected to take a long delay before officials begin developing an ultra-low nitrogen oxide (NOx) standard for heavy-duty trucks, which the agency late last year agreed to pursue in response to a petition by California and other state clean air agencies as well as environmental groups.

Livestock industry groups are defending EPA's rule for when states can discount emissions associated with natural "exceptional events" such as wildfires from counting toward their compliance with federal air standards, fighting environmentalists' claim that the rule unlawfully allows too many human activities to be considered as such an event.

Electric utilities are urging the Supreme Court to hear Michigan utility DTE Energy's challenge to EPA's new source review (NSR) air permit enforcement policy, arguing that actual emissions, not only projected emissions, should determine if a facility needs an NSR permit, and that the program needs a broad overhaul to ease regulatory obstacles.

U.S. Court of Appeals for the District of Columbia Circuit judges at Sept. 15 oral argument wrestled with what one judge called EPA's "black box" scientific rationale for setting a limit on carbon monoxide (CO) as a "surrogate" for reducing air toxics from boilers, though the fate of a suit over the agency's boiler air toxics rule remains unclear.

With appointments for numerous EPA science advisors expiring at the end of the month, Administrator Scott Pruitt faces challenges selecting new members to the agency's Clean Air Scientific Advisory Committee (CASAC) and Science Advisory Board (SAB), selections that could intensify criticism over the administration's scientific views.

President Donald Trump has nominated Bill Wehrum, the acting head of EPA's air office during the Bush administration, to lead the Trump administration's efforts to undo Obama-era air and climate policies.

Environmental groups and federal employee unions are ramping up their defense of EPA's budget in fiscal year 2018, readying efforts to shore up support in the Senate by citing recent massive hurricanes to highlight the need for adequate agency resources to address short- and long-term consequences of the cleanup effort.

JACKSON HOLE, WY -- State environmental regulators are seeking to create a process for streamlining approvals of new oil and gas emissions control technologies for use in complying with EPA and state rules, hoping broad regulatory acceptance will spur innovation and adoption of new technologies for measuring or limiting emissions in natural gas fields.

A three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit appeared dubious during Sept. 19 oral arguments of environmentalists' claims against EPA's revised guidance for how states should evaluate air pollution 'hot-spots' resulting from highway construction, focusing their discussion entirely on jurisdiction and standing issues -- not the merits of the guide itself.

The U.S. Court of Appeals for the District of Columbia Circuit has scheduled oral argument for Nov. 16 in a long-delayed case testing whether states can rely on power plants' participation in EPA's Cross-State Air Pollution Rule (CSAPR) as an alternative to source-specific control technology to curb haze-forming pollution.

Two massive hurricanes that have caused devastating flooding damage in the Southeast during the past month have renewed a public debate about how climate change is intensifying extreme weather events, though it remains uncertain whether such discussion will spur additional federal climate mitigation or adaptation policies.

EPA in a new court filing is pledging to release its proposal to rescind the Clean Power Plan (CPP) greenhouse gas rule for power plants this "fall" after previously describing the effort as a years-long action, arguing that appellate judges should keep litigation over the Obama-era rule on hold pending release of the upcoming rule.