From July to November 2016, Delaware and Maryland respectively (and together) filed Clean Air Act 126(b) petitions to the Environmental Protection Agency (EPA) alleging that upwind states such as Pennsylvania, West Virginia, Indiana, Kentucky and Ohio were significantly contributing to their non-attainment of eight-hour ozone national ambient air quality standards (NAAQS). On 8 June 2018 the EPA published its notice of proposed action denying each of these 126(b) petitions. Section 126(b) petitions relate to the Clean Air Act's 'good neighbour' provision, which requires states to factor in their potential contributions to downwind state non-attainment of NAAQS when developing and submitting state implementation plans.

Section 126(b) petitions allow individual states to ask that the EPA set emissions limits for specific sources of air pollution significantly contributing to the non-attainment. Most recently, New York filed a 126(b) petition with the EPA alleging that nine downwind states significantly contribute to its non-attainment of the 2008 and 2015 ozone NAAQS. The deadline for the EPA to act on the petition has been extended until early November 2018. The EPA has already finalised its denial of a similar 126(b) petition made by Connecticut in 2016 and is accepting comments on its proposed denial of Delaware and Maryland's 126(b) petitions until 23 July 2018. The agency also proposes to hold a public hearing on the matter.

For further information on this topic please contact Samuel B Boxerman or Jim Wedeking at Sidley Austin LLP by telephone (+1 202 736 8000) or email ( or The Sidley Austin LLP website can be accessed at

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