1. Department of the Environment Near Road NO2 Monitoring Update MWAQC Technical Advisory Committee January 10, 2012

2. Background  NO2 NAAQS revised 1/22/2010  1-hour level set at 100 ppb  Monitoring required in urban area near major roadways where maximum concentrations are expected by Jan. 1, 2013  One near road monitor for areas with population > 300,000, additional monitor for areas with population > 2.5 million  Two monitors required for the DC/MD/VA CBSA and two monitors in the Baltimore CBSA

3. Build and Hold Plan  In response to concerns raised by NACAA and CASAC over the expeditious deployment schedule and resource/budgetary issues facing the States and EPA. EPA has developed the Build and Hold plan  Initial deployment of near road monitors now limited to areas with population > 1 million (subset of original requirements), one monitor per area.  Monitors to be deployed over two years (2013 and 2014)  Goal is to establish a sufficient base of monitors across the country so ambient concentrations can be assessed before deciding on whether to implement the full network

4. Build and Hold Plan  Build and Hold now means one monitor in the DC/MD/VA CBSA and one monitor in the Baltimore CBSA, both by Jan. 1, 2013  No formal revision to the existing monitoring requirements at this time  EPA and States left vulnerable to legal action

5. Site selection for Pilot study NO2 near-road rule  “EPA proposed that the near road monitoring stations shall be selected by ranking all road segments within a CBSA by AADT (Annual Average Daily Traffic) … where maximum hourly NO2 concentrations are expected to be highest and siting criteria can be met. …. (other factors to consider) include vehicle fleet mix, roadway design, congestion patterns, terrain, and meteorology.” The NO2 Technical Assistance Document developed a metric, the Fleet Equivalent (FE) AADT, to account for fleet mix and traffic counts  FE-AADT = (AADT – HD) + HD*10  HD = heavy duty counts  Factor of 10 is national average ratio of heavy duty NOx emissions / light duty NOx emissions Below are the top 20 AADT and FE-AADT segments in the Baltimore CBSA and population densities. Top 20 AADTTop 20 FE- AADT

6. Comparing AADT to FE-AADT rank

7. Sites chosen for pilot study

8. Results  These results are weekly averages, NOT the 1-hr standard.  Baltimore and Albuquerque measured the largest NO 2 values.  Baltimore also measured the largest background concentrations  The largest NO 2 was collected at the rest area and the tollbooth  Rest area is a better location because tollbooth is influenced by background sources (port, tunnel, industry etc.).  Rest area may be influenced by idling trucks.

9. Results (cont.)  In general NO 2 increases with AADT (and FE-AADT).  Circled outlier is tollbooth with possible background influences.  Outliers highlighted with square were influenced by roadway design.

10. Near road pilot study extension  We found slightly higher NO 2 at the tollbooth site than at the rest area site. This is likely due to background sources.  Our plans are to locate a permanent monitor at the rest area site.