Division of Air Pollution Control 

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 you are 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 to be 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, as these samples 

were analyzed by a different 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 

one or more critical validation criteria should be considered invalid for regulatory purposes. 

Guidelines for determining the validity of ambient air samples are found 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 are essential to the quality of the resulting data. The handbook identifies laboratory 

temperature and relative humidity control requirements as critical criteria for PM2.s and states: 

Observations that do not meet each and every criterion on the Critical Criteria Table 

should be invalidated unless there are compelling reason[s] and justification for not doing 

so. The sample or group of samples for which one or more of these criteria are not met is 

invalid until proven otherwise. 

In making this preliminary data validity determination, the EPA reviewed and analyzed multiple sources 

of information related to the samples in question, including supporting quality assurance data 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 Vegelable od Based Inks on Recycled Paper (Minimum :ul% Poslconsumer) 
The EPA Region 4 also discussed this preliminary decision with EPA • s Office of Air Quality Planning 

and Standards and other Regional Offices to ensure national consistency. 

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

supporting materials before completing our analysis and making a final data validity determination. 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 data). This chaHge will clarify to data users that data from these sites should not be compared 

to the PM2.s National Ambient Air Quality Standards until the EPA has made a 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 analysis and made a final validity determination. 

Please contact me, or contact Gregg Worley at (404) 562-9141, if you have any questions about this 

preliminary determination. 

Sincerely, 

~.!~

~~~ 

cc: Ms. Lynne A. Liddington, Department Head 

Knox County Air Quality 

Mr. Robert Rogers, Technical Manager 

Director 

Air, Pesticides and Toxics Management Division 

Shelby County Health Department Pollution Control Section 

Mr. Bob Colby, Director 

Chattanooga-Hamilton County Air Pollution Control Bureau 

Mr. John Finke, Director 

Nashville/Davidson County Metro Public 

Health Department Pollution Control Division 

Mr. Mike Peyton 

EPA Region 4 Science and Ecosystems Support Division