Green Roof Resource

To update from a previous post, not only did US Court of Appeals District of Columbia Circuit rule that the clean air mercury rule violated the Clean Air Act in February, but in July the District of Columbia Circuit also vacated the clean air interstate rule (CAIR). While the court vacated the CAIR rule, the NOx State Implementation Plan is still valid. However, as the NOx Budget Trade Program (BTP) was set to expire prior to the 2009 ozone season to make way for CAIR, state regulators have been urged to revise their programs to extend the NOx SIP call. Meanwhile, on September 24th the US filed a petition to the court for a rehearing of the CAIR case.

So why should we care about CAIR or the NOx BTP? The NOx BTP has effectively reduced NOx emissions by 74% between 1990 and 2006 [1]. The ozone season NOx emissions have dropped from 1.86 million tons in 1990 to 491 thousand tons in 2006. During the same period, the 8-hour average ozone concentration decreased across all states participating in the program with significant reductions occurring in New York, Pennsylvania, Virginia, and West Virginia [1]. While there remain areas that are not in attainment of the 8-hour ozone standard, most areas within the NOx BTP have shown improvement suggesting that there is a benefit to implementing such a program whether the CAIR ultimately is accepted or the NOx BTP is extended.

Reference:
[1] US EPA. Office of Air and Radiation. NOx Budget Trade Program: 2006 Program Compliance and Environmental Results. EPA-430-R-07-009. 2007.

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