The U.S. Environmental Protection Agency (EPA) recently issued a final rule giving states an additional year to begin monitoring for nitrogen dioxide near roads. 78 Fed. Reg. 16,148 (3/14/13). EPA had previously issued regulations requiring nitrogen dioxide monitoring networks near roads to be complete by January 1, 2013. The new rule uses a phased approach that calls for the activation of (i) 52 near-road monitors in core based statistical areas (CBSA) with more than 1 million people by January 1, 2014; (ii) 23 monitors in CBSAs with more than 2.5 million people or in those CBSAs that have more than 500,000 people and road segments averaging 250,000 or more daily traffic counts by January 1, 2015; and (iii) 51 monitors in CBSAs with a population between 500,000 and 1 million people by January 1, 2017.