U.S. EPA Proposes a Short-Term NO2 NAAQS

In the more than 200 air quality modeling analyses that ALL4 meteorologists have conducted, demonstrating compliance with the annual nitrogen dioxide (NO2) National Ambient Air Quality Standard (NAAQS) of 53 parts per billion (ppbv) has rarely been very difficult.  The ability to easily demonstrate compliance with the annual NO2 NAAQS is due to two factors.  First, the NAAQS for NO2 is on an annual basis and thus any adverse dispersion that occurs based on worst-case meteorological conditions is averaged over the course of a year, minimizing its affect.  Second, U.S. EPA recommends the use of scaling factors to adjust the modeled concentrations of oxides of nitrogen (NOx) to reflect the fact that NOx is converted to NO2 after being emitted from the source.  This adjustment results in a reduction of the modeled annual concentrations.  

On June 29, 2009, U.S. EPA announced that they were proposing to establish a new short-term NO2 NAAQS between 80 and 100 ppbv.  The establishment of a short-term NO2 NAAQS may make it more difficult for NO2 air quality modeling analyses to demonstrate compliance with a NAAQS compliance demonstration under New Source Review (NSR).  Specifically, a short-term standard would reflect worst-case dispersion conditions and elevated modeled concentrations due to a combination of either building aerodynamic downwash or adverse meteorological conditions.  Based on ALL4 modeling experience, SO2 air quality modeling analyses often hinge on compliance with the existing 3-hour SO2 standard.  The ratio between the SO2 3-hour NAAQS (500 ppbv) and the annual SO2 NAAQS (30 ppbv) is 16.7, while the ratio between a 1-hour NO2 NAAQS (100 ppbv) and the annual NO2 NAAQS (53 ppbv) is 1.9.  The lower ratio for NO2 indicates that, relative to SO2, it will be more difficult to demonstrate compliance with a new 1-hour NO2 NAAQS than with the existing 3-hour SO2 NAAQS.  With the proposed new NO2 NAAQS targeted for January 22, 2010, facilities may be well served to perform some exploratory air quality modeling analyses to evaluate compliance with a new NAAQS.

Court Rules on Phase 2 Ozone Rule

On June 10, 2009, the U.S. Circuit Court of Appeals for the District of Columbia remanded (without vacatur) two areas of the Final Rule To Implement the 8-Hour Ozone National Ambient Air Quality Standard – Phase 2 (Phase 2 Rule) and remanded (with vacatur) a third area of the Phase 2 Rule. The areas of the rule that were affected by the Court’s decision are summarized below:

• The Court ruled (remanded without vacatur) that the Phase 2 Rule violated the Clean Air Act (CAA) by allowing participation in the NOx SIP Call in lieu of mandating specific reductions within a non-attainment area through the application of Reasonably Available Control Technology (RACT) requirements.
• The Court also ruled (remanded without vacatur) that U.S. EPA acted arbitrarily when it eliminated the requirement for an attainment demonstration for an area to be approved before a new source is allowed to use a past emission reduction to offset a new emissions increase.
• Finally, the Court ruled (remanded with vacatur) that the elimination of 18-month time waivers under Appendix S is in violation of the anti-backsliding provisions of the CAA. 

Click here to view the full text of the ruling.

Do You Need A Quality Assurance Performance Plan (QAPP)?

The proposed Mandatory Greenhouse Gas (GHG) Reporting Rule  (40 CFR Part 98) issued in March 2009 would require the economy-wide reporting of emissions data from facilities or sources that emit 25,000 metric tons or more per year of GHG emissions.  40 CFR §98.3(g)(11) proposes that sources develop and maintain a written Quality Assurance Performance Plan (QAPP) that describes the procedures for maintenance, repair, calibration, and other quality assurance (QA) activities for all continuous monitoring systems, flow meters, and other instrumentation used to provide data for the GHG emissions reported.  The QAPP would serve as a road map for collecting valid monitoring data.  Specifically, the QAPP should document the procedures involved with the acquisition of emissions data and operating information. Aggressive planning for data collection and maintenance activities will allow for early detection of problems and will increase the effectiveness and efficiency of a data management program.  A QAPP should be completed and submitted for review and approval before the data collection project is initiated.  Although the approved QAPP must be implemented as prescribed, it should be flexible as changes to original plans are often needed.  The QAPP should be a “living document” that is reviewed frequently and updated according to facility needs and operations.  Significant steps toward developing a QAPP include: 

• Assessing what needs to be done based on what is known about the site and regulatory requirements.
• Assembling a project team with the necessary expertise.
• Determining the actions needed to obtain relevant and accurate data to support the project.
• Writing the QAPP.
• Submitting the QAPP for review and approval. 
• Implementing the QAPP.

U.S. EPA has proposed that data collection for GHG reporting begin for the calendar year 2010, with reports due in 2011.  This would require sources to develop and implement a QAPP prior to December 31, 2009.