### UNITED STATESENVIRONMENTAL PROTECTIONAGENCY New England Regional Laboratory 11 Technology Drive, North Chelmsford, MA 01863

November 13, 2015
Christine Kirby, Director, Division ofAirand Climate Programs Bureau ofWaste Prevention Department ofEnvironmental Protection One Winter Street Boston, MA 02108
Dear

### Ms. Kirby:
Thankyou for your submission ofthe Massachusetts 2015 Annual Monitoring Network Plan whichwas submitted to us in final form on October 14,2015. We appreciate thatyou addressed the comments we providedto youonJuly 29, 2015. I amalso aware ofthe letteryou sentto Robert Judge onNovember 10,2015 regarding discontinuing lead monitoring in Springfield. EPANew Englandhas evaluated your plan and finds thatyour planmeets the minimum requirements of40 CFRPart 58.
We acknowledgethe following modifications and future plans which you articulated as follows (in italics): P1·oposedNetwork Changes • MassDEP closedthe Boston -LongIslandozone site (25-025-0041) in October 2014 due to the removal of the bridge to the island

• MassDEP closedtheAmherstozone site (25-015-0103) in June 2014 when site conditions couldno longer supportmonitoring.

• MassDEP addedPM1o andPM1o-leadmonitoringto the Springfield- LibertyStreetsite (25-013-0016) andclosedthe Springfield- Main Street (25-013-2009) PMw andPM2.5 site atthe endof June 2014.

• lvfassDEP closedthe Boston- CitySquare (25-025-0027) PMw andPM2.s site at the end of2014.

• MassDEP discontinued COmonitoringat the Boston -Kenmore Square (25-025-0002) site atthe endof2014. MassDEP has installedanAutosampling GC (for Toxic VOCs) at that location.

• Constellation Generation Company, LLCclosed itsprivate monitoringsite in Boston at the endof June 2014.

• MassDEP closedtheAdams/MI. Grey/ockozone site (25-023-4002) atthe endof the 2014 ozone season due to the dijjicultyandcostof requiredimprovements neededat the site, MassDEP alreadywasplanningto close thissite, andis in theprocessing of finding acomprehensive population-oriented ozone and P M2.s site in Berkshire County to consolidate and replace the Adams site and two P M2.s monitoring sites currently located in Pittsfield. • MassDEP is not processing data for the Newburyport and Ware PAMS sites in 2015 to enable MassDEP to catch up on a data backlog. MassDEP would process the data for

these sites again beginning in 2016, depending on new monitoring requirements associated with a revised ozone standard, expected to be final in October 2015. • MassDEP is in the process of locating a second Boston Area near-road N02 site in the vicinity of the Route 495/Route 3 intersection north Of Boston. • MassDEP plans to install a second FEM PM2.s monitor at Boston- Von Hillern Street (25-025-0044) for Quality Control and Assurance purposes. • MassDEP plans to discontinue FEM Plv.hs monitoring at the Milton- Blue Hill site (25- 021-3003) at the end of2015. Per the discussion in the above paragraph, all network modifications that involve discontinuation or moving of ap.y sites is subject to EPA approval, even if the remaining network meets EPA's minimum requirements. Regarding the recent request to no longer measure lead in Springfield at the end of2015, we understand and support the request; and note those measurements are beyo.Q.d what is required to meet federal air monitoring obligations. Since this was not included in your proposed plan, I would encourage you to include that in next year's proposed Annual Network Plan in case there are public concerns that neither MassDEP nor we are aware of regarding the need to continue, or resume, monitoring for lead at this location. In light of possible future state and federal budget restrictions, we encourage MassDEP to consider further savings measures and discuss those opportunities with the EPA prior to implementation. EPA has finalized its Data Requirements Rule for the**l~Hour** Sulfur Dioxide Primary National Ambient Air Quality Standard (NAAQS) on August 21, 2015 (80 FR 51052), and provided detailed monitoring and modelling guidance for implementing the S02 standard. EPA looks forward to future dialogue with MassDEP regarding any additional monitoring that it may be consider relative to the fmalized DRR. We also note your acknowledgement that the Harrison Avenue (25-025-0042), Boston- Kenmore Square (25-025-0002), and Springfield- Liberty Street (25-013-0016) sites have been approved as among the 40 N02 monitors intended to help protect

communities that are susceptible or vulnerable to N02 related health effects pursuant to 40 CFR Part 58, Appendix D, section 4.3.4(a). Further, consistent with 40 CFR 58.ll(e), I am approving the exclusion ofPM2.scontinuous data from one of your continuous PM2.s monitors. Thank you for your submission of the Demonstration ofPM2.s Comparability included in this Plan. As you know, this included your analysis of your continuous PM2.s Federal Equivalent Methods (FEMs) as compared to collocated PM2.s Federal Reference Methods (FRMs). This comparison is required under 40 CFR Part 58.1I(e) for any cases where PM2.s continuous FEM data should not be used in comparison to the NAAQS. Y au discussed the 13 continuous PM2.s FEM monitors your network. Y au indicated that MassDEP will use data from its FEM monitors for comparison to the NAAQS, with the exception of the new FEM monitors at Greenfield - Veterans Field since this monitor has less than 24 months of data (as provided under EPA regulation), and the FEM monitor at Springfield - Liberty Street because this monitor continues to not have acceptable data comparability withthe collocated FRM monitor. 

### Inthe case ofSpringfield- Liberty Street, the analysis shows that the performance is outside ofthe acceptable range. Sinceyouhave demonstrated that this monitor does not meet requisite performance criteria, butyou believe this data is acceptable for AQIpurposes, we agree the datafrom this monitor shouldbe reported usingparameter code of 88502, indicating that this data is appropriate for AQI use, butnot for comparisonto the National AmbientAir Quality Standard (NAAQS). Should you determine this data notbe ofacceptable quality for neither AQI reporting or for comparisonto the NAAQS, parameter code 88501 shouldbe used. You should continue reporting to the sameparameter code when generating any newdata with the 

### PMz.s continuous FEMs. (Note that the network design requirements for 

### PMz.s remain in effect. Your agency will berequired to operate FRMs orother FEMs at all required sites to be used for comparisonto the NAAQS.) Ifyou determine that the continuous monitor approved for exclusion is operating within acceptable ranges, it shouldbe coded as 88101, and the next Annual Network Plan should describe that change. The monitors specifically identified as not appropriate for NAAQS comparison since 2010 follow (sites will be coded as 88502, as eligible to be reported for AQI purposes, butnot NAAQS compliance): I) 25-013-0016 Liberty Street- Springfield 2) 25-011-2005 Veterans Field- Greenfield Regarding future annual monitoring network plans, please identifythe PMz.s continuous FEMs and anypre-FEM continuous monitors in use orplanned for use in your network. Yourplan should clearly indicate the 

### PMz.s continuous monitors inyour network, and whether they have already been approved (pursuant to this or other approval letter) to be excluded from comparison to the NAAQS. To maintain such waivers, each subsequentAnnual NetworkPlanmust detail the 

### PMz.s continuous FEMs, where they are located, and the monitoring objectives thatthey will support (i.e., eligible for use withthe NAAQS and/or AQI) for the comingyear. We also recommend that an assessment oftlle most recent three years ofdatafor all collocated FRM/continuous FEM monitors be includedin each subsequent annual planwhere the m·onitoring agency wishes to continue to exclude such data from comparisonto the NAAQS. Since this approval for exclusion ofdata covers two monitors, tills shouldbereassessed next year, along with any newer continuous PMz.s monitors that may have operatedfor more than 24 months. Specifically, nextyear, the Greenfield monitor will have operated for more than 2 years, and MassDEP should reevaluate the Liberty Street- Springfield monitor.
We also urge you to move forward inreplacing the Adams ozone monitor and inrelocating 

### PM2.5 monitoring fi:om their current locations in Pittsfield. We standready to assist you identify appropriate locations. As we suggested in our July 29, 2015 public comments onyourplan, and as our staffs discussed inperson on November 12, 2015 we believethere are a number of locations in westernMassachusetts' valleys which maybenefit from PM2.5 air quality measurements. As youknow, EPA has been conducting an assessment oftl1e IMPROVE Protocol Sites in an effort to optimize the Chemical SpeciationNetwork (CSN) and create a network that is sustainable going forward. As a result ofthis assessment, EPA is recommending defunding a number ofmonitoring sites- including the Ware- Quabbin Summit site (25-015-4002). Any changes are recommended to takeplace inJanuary 2016. Finally, in this approval, I recognize thatMassDEP has finished the process ofidentifying a suitable location for a secondnear-road monitoring station in the Boston CBSAnear the Route 495/ Route 3 intersection north ofBoston. As youknow, 40 CFRPart 58.10(a)(iv) requires thatthis site begin operation by January I, 2015. EPA is committed to work with you expeditiously to assist you in meeting this requirement. With this letter, I am approving your Annual Network Plan. We will work with our Headquarters offices to address the portions of the plan which would require their attention, most notably monitoring associated with NCore, IMPROVE, PAMS, and STN. EPA-New England appreciates your partnership in conducting ambient air monitoring. We look forward to working with you to continuously improve the quality of ambient air in Massachusetts. If you have any questions or comments regarding this network review, please contact Bob Judge at (617) 918-8387. irector Office of Environmental Measurement and Evaluation

EPA New England cc: Glenn Keith, MassDEP