Democratic attorneys general (AGs) and environmentalists are rushing to defend EPA’s longstanding view that consideration of costs in setting national ambient air quality standards (NAAQS) is barred under the Clean Air Act and Supreme Court precedent, in litigation over tougher particulate matter (PM) limits that revives this fundamental question. In an Oct. 15 final brief in Commonwealth of Kentucky, et al., v. EPA et al. , Democratic AGs from 16 states, New York City, the District of Columbia and Harris...