UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION4 Mr. Barry R. Stephens, PE Director Division of Air Pollution Control ATLANTA FEDERAL CENTER 61 FORSYTH STREET ATLANTA, GEORGIA30303·8960 **~UG**0a 20\4 Tennessee Department
of Environment and Conservation William R. Snodgrass Tennessee Tower 312 Rosa L. Parks Avenue, 15th Floor Nashville, Tennessee 37243 Dear Mr. Stephens: As youare aware,the U.S. Environmental Protection Agency Region

4 technical systems audit (TSA) of the Tennessee Department
of Environment and Conservation (TDEC) ambient air monitoring program conducted on September 9-12,2013, indicated that a large portion of the fine particulate (PMz

.s) samples analyzed by the State of Tennessee laboratories

in Nashville and Knoxville during multiple timeframes ranging from 2008-2012 did not meet all of the requirements
of the federal reference method for PMz.s found in 40 CFR Part 50, Appendix
L. Specifically, the TSA found that environmental control problems in both laboratories caused filters tobe weighed under temperature and humidity conditions outside of the allowable ranges.The EPA also noted problems with the temperature and humidity control systems at both laboratories

in its previous TSA, conducted
in 2010. Please note that these findings do not affect samples collected by the Chattanooga-Hamilton County Air Pollution Control Bureau, asthese samples were analyzed by adifferent laboratory. After review of the available information and records related to the affected samples, the EPA has made
a preliminary determination that all samples that did not meet oneormorecritical validation criteria should be considered invalid for regulatory purposes. Guidelines for determining the validity of ambient air samples arefound in the QA Handbook for Air Pollution Measurement Systems, Volume II (May, 2013 ). This document provides data validation templates for each of the criteria pollutants, including PMz

.s.These templates identify specific "critical criteria,. which areessential tothe quality of the resulting data. The handbook identifies laboratory temperature and relative humidity control requirements

ascritical criteria for PM2.s and states: Observations that do not meet each and everycriterion onthe Critical Criteria Table should be invalidated unless there are compelling reason[s] and justification for not doing so.The sample or groupof samples for which oneormoreof these criteria arenot met is invalid until provenotherwise

. In making this preliminary data validity determination,
the EPA reviewed and analyzed multiple sources of information related tothe samples in question, including supporting quality assurancedata provided by the state's Nashville and Knoxville laboratories and TDEC, the draft results of the temperature and humidity study that TDEC provided, and related scientific literature

. Internet Address (URL)

• http'//www

.epa

.gov Recycled/Recyclable

•Prlnlad wllh Vegelableod Based Inks on Recycled Paper (Minimum :ul% Poslconsumer)The EPA Region 4 a lso discussed this preliminary decision with EPA•s Office of Air Quality Planning

and Standards and other Regional Offices toensure national consistency.

Aswe discussed recently, the EPA is waiting to evaluate the final report for TDEC's filter study and

supporting materia ls before completing our analysis and making a final data validity det ermination. In

the Air Quality System database, the EPA has moved the data for the PM2.s sites in question from

parameter code 88101 (PM2.s at local conditions; used for regulatory data) to parameter code 88501

(PM2.s raw d ata). This chaHge will clarify to datausers that data from these sites should not be compared

to the PM2.s National Ambient Air Quality Standards until the EPA has madea final validity
determination. No other changes to this dataset have been made at this time. The EPA will notify you

once it has completed its analys is and madea final validity determination.

Please contactme, or contact Gregg Worley at (404) 562-9141, ifyou haveany questions about th is

preliminary determination. Sincerely, **~.!~ ~~~** 

cc: Ms. Lynn e A. Liddington, Dep art ment Head

Knox County Air Quality

Mr. Robe rt Rogers, Technical Manager Director Air, Pesticides and Toxics Management Division

Shelby County Health Department Pollut ion Control Sec t ion

Mr. Bob Colby, Director Chattanoog a -Hamilton County A ir Pollution Control Bureau

Mr. John Finke, Director Nashv ille/Davidson County Metro Publ ic
Health Department Pollution Contro l Division

Mr. Mike Pey ton EPA Region 4 Science and Ecosy stems Support Division