Since the 1-hour sulfur dioxide (SO2) National Ambient Air Quality Standard (NAAQS) became effective in August 2010, ALL4 has been tracking it every step of the way. Its implementation has proven to be chaotic at times and quiet at others. As we are ramping up into our air regulatory reporting obligations for 2014, U.S. EPA’s implementation of the 1-hour NAAQS is ramping up as well. This article will discuss where the 1-hour SO2 NAAQS has been, where it is going, and what you can do to plan for 2014 and beyond. Before we can look forward, we need to revisit how we got to this point.
1-Hour SO2 NAAQS: A History
The implementation process for the 1-hour NAAQS has been unique relative to previous NAAQS. As we know already, the NAAQS level was set at 75 parts per billion (ppb) measured as the 99th percentile of the maximum daily concentration over a period of three (3) years. The following subsections provide a brief history of the twists and turns of U.S. EPA’s NAAQS implementation process.