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Quality Assurance Project Plan

TDEC PM2.5 Filter Investigation Study

Performed by RTI for the Division of Air Pollution Control

Ambient Air Quality Monitoring Program

June 17, 2014
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Table of Contents 

Table of Contents Transferred to Report Table of Contents............................................... 2

Quality Assurance Project Plan Identification and Approval............................................... 3

Background................................................................................................................................ 4

Project/Task Description .......................................................................................................... 5

Description of Work to be Performed ..................................................................................... 6

Laboratory Activities................................................................................................................ 6

Project Records.......................................................................................................................... 6

Data and Measurement Quality Objectives and Criteria...................................................... 6

General Data Quality Objectives........................................................................................... 16

Training Requirements........................................................................................................... 16

Documentation and Records .................................................................................................. 16

Sample Custody Procedure .................................................................................................... 16

Analytical Methods Requirements......................................................................................... 16

Quality Control Requirements............................................................................................... 17

Equipment Acceptance Testing and Maintenance ............................................................... 17

Instrument Calibration........................................................................................................... 17

Requirements for Supplies and Consumable........................................................................ 18

Acquisition of Data.................................................................................................................. 18

Data Storage and Management Activities............................................................................. 18

Data Validation........................................................................................................................ 18

Final Data End User Requirements....................................................................................... 18
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Quality Assurance Project Plan Identification and Approval

Title: QUALITY ASSURANCE PROJECT PLAN

TDEC PM2.5 Filter Investigation Study

The Quality Assurance Project Plan is hereby recommended for approval and commits the 

State of Tennessee APCD to follow the elements described within.
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Background

The TDH laboratories in Nashville and Knoxville have provided laboratory analysis and 

sample media preparation services for TDEC Air Pollution Control for a number of years. 

In early 2000, the lab began processing PM2.5 filters for Air Pollution Control and other 

agencies operating PM2.5 networks in Tennessee. The laboratory was provided funding 

through the 103 PM2.5 Grant program to acquire the necessary equipment to outfit and 

operate a PM 2.5 weighing lab in Nashville. This was later expanded to include another 

operational lab in the Knoxville TDH environmental lab.

EPA provides strict criteria that must be followed by a weighing laboratory if it is 

performing weighing analysis for PM2.5 filters. Specialized weighing equipment (micro 

balance), temperature and humidity controlled weighing environment and other 

requirements must be met and maintained on an ongoing basis in order to perform 

weighing analysis. Filters that are initially weighed at one laboratory must be returned to 

the same laboratory for final weighing and must also be processed within a fixed 

timeframe. Filters once exposed must be returned for analysis either immediately or kept 

under refrigeration and return shipped to the lab for analysis.

During the period from 2010 through August 2012, the TDH laboratories in both 

Knoxville and Nashville began experiencing significant problems with the environmental 

controls used to maintain the temperature and relative humidity in the PM2.5 weighing 

rooms operated by each facility. These deviations from the acceptable ranges of 

temperature and humidity resulted in an increasing number of filters being identified by 

the two laboratories as not meeting the criteria set by EPA for valid PM2.5 data and 

potentially subject to being flagged or invalidated because of these excursions in the 

environmental conditions within the weighing laboratories.

EPA has defined the acceptable operational conditions for a PM2.5 weighing laboratory 

and has periodically evaluated the laboratories in Knoxville and Nashville during 

Technical System Audits (TSA) that are performed by EPA normally once every three 

years. EPA performed a TSA during the week of September 9 to 13, 2013 during which 

the PM2.5 data generated by the state lab(s) were also evaluated for the period from 2010 

through 2012. During this audit it was determined that the laboratories failure to properly 

maintain environmental conditions during PM2.5 filter processing significantly impacted 

the quality of the resulting PM2.5 data being reported by the laboratory and provided to 

the Division of Air Pollution Control for use in defining air quality and determining 

compliance with the NAAQS for fine particulate matter. EPA further recommended that 

instead of flagging the affected data impacted by the excursions of laboratory temperature 

and humidity conditions during weighing, that invalidation of the affected data should be 

performed. (November 21, 2013 EPA Final TSA Report Section 2. Summary follows)
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“The TSA for the State of Tennessee revealed two major concerns and several 

other concerns with respect to the ambient air monitoring program. The first 

major concern was the significant portion of PM2.5 data flagged with a “1” in the 

AQS during 2011-2012. The State operated two PM2.5 weigh laboratories at the 

time of this audit. Both of these labs began experiencing environmental control 

problems (temperature and relative humidity). Efforts were made by the State to 

repair the failed environmental systems. These repair efforts were unsuccessful, 

with a cycle of repair and failure until the decision was made to contract a private 

laboratory to take over all of the weigh laboratory duties until replacement of the 

environmental systems could be accomplished. The State decided to close one of 

its laboratories (Knoxville) and focus all efforts into the Nashville lab. The “1” 

flag is an indicator of a “critical criteria” for this pollutant measurement method 

not being met. EPA guidance recommends data not meeting a critical criteria be 

invalidated. EPA Region 4 has consistently followed this guidance and will 

recommends the State invalidate this data unless it can present evidence as why it 

should be retained. The data impacted was collected from mid 2011 through mid 

2012 for the State, Memphis, Nashville and Knoxville agencies and totals 

approximately 30% of the data set for each of these agencies. EPA Region 4 is 

recommending the TDEC-DAPC review data back through 2010 for this issue.”

The impact of the proposed invalidation of the affected data for the state and local 

program PM2.5 monitoring networks could be very significant as the network monitors 

are required to collect and report at least 75% of the data and to have that data available 

for a contiguous 3 year period to use in calculation of the design values for the sites and 

areas the monitors represent. An initial evaluation of the entire dataset during the period 

from January 1, 2010 to December 31, 2012 indicates that both the state and local 

programs that were customers of the TDH environmental laboratories in Knoxville and 

Nashville potentially will have insufficient PM2.5 data available to calculate valid design 

values for a number of the monitoring sites operating during this period of time.

Project/Task Description

An investigation was started immediately upon receiving the preliminary EPA remarks 

and comments during the exit interview into the extent of data affected and possible 

options to resolve the potential loss of a significant portion of the existing PM2.5 datasets 

already processed and loaded into the EPA’s AQS subsystem. 

Some options are being investigated to further identify and possibly recover data that 

may be currently flagged but statistically meet the definition of the criteria for exclusion 

but in reality are still valid. Additionally a study is being considered to evaluate the 
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effect that excursions of temperature and humidity may have on filter weighing in an 

effort to assign a specific amount of impact to the ranges of temperature and humidity 

experienced during filter processing by the TDH labs.

Description of Work to be Performed

Contract with a recognized commercial PM2.5 weighing laboratory to perform 

reweighing of previously exposed “archived” PM2.5 filters at temperature and humidity 

ranges outside of the normally acceptable temperature and humidity levels and determine 

the difference (if any) in the same set of filters all initially weighed at normal laboratory 

conditions and then at lower and higher conditions relative to the acceptable extreme 

lower and upper ranges for temperature and humidity.

Laboratory Activities

The following requirements must be met and maintained by a weighing laboratory that is 

processing PM2.5 filters. The specific requirement listed in the CFR, QA Guidance 

Document 2.12 and the excerpt from the Critical Criteria Tables provided by EPA in the 

data validation templates provide the actual requirements PM2.5 weighing labs must 

meet and maintain in order to properly process PM2.5 filters.

Project Records

Because the previously exposed filters are already identified and catalogued by the TDH 

labs in their laboratory PM2.5 filter record and data and processing system, there will be 

additional documentation and records generated by the contract lab during their receipt, 

processing and weighing/reporting of the mass values generated during the filter study. 

A report of all necessary data will be requested to be provided by the contract lab 

including all needed documentation of the laboratory conditions to ensure all stability and 

control requirements are met during both the normal and extreme temperature and 

humidity weighing operations.

Data and Measurement Quality Objectives and Criteria

The DQO’s (Data Quality Objectives) were determined in part based upon the following 

questions to consider.

1. What will be the criteria for selection of filters to be included in the reweighing 

study?

There will be only a limited number of PM2.5 filters available for re-weighing by 

the contract lab given that only filters that have already been sampled with and 

placed into archive will be employed and only those of recent sampling dates will 

be selected. The entire population of affected and unaffected filters will not be 

subject to reweighing because of cost, time and age of the filters in question. In 

this study filters that were collected in late 2013 and early 2014 would qualify to 
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be included. An examination of the available filter population revealed that filter 

meeting these criteria were available for selection.

2. What is the statistically significant number of samples to select to represent the 

entire population of affected filters?

The contract lab was contacted to determine a statistically valid number of filters 

to employ in the study. The number suggested by the contract lab was 30-50 

filters based on the statistical power analysis for the number of samples needed to 

be 95% certain a difference between the two populations of weighings actually 

existed (i.e., two different environmental conditions). This sample size was also 

based on historical gravimetric precision and that in the FRM Acceptance Testing 

that the average any two weights can differ by is up to 10 ug and still be deemed 

‘passing’ the moisture pickup acceptance test. The following data suggest that 

this number of filters may be sufficient for the purposes of this study.

In the table above the total number of filters produced for use in the 2014 

sampling year by MTL and acquired for distribution by EPA (TRC) to the state 

sampling agencies nationwide were slightly over 211,000 filters. TRC supplied 

50 filters to RTI to perform the required moisture pickup acceptance testing 

representing the entire lot of filters. This is approximately 0.02% of the total. 

Tennessee collected on average 4200 creditable filters each year for the 2010 to 

2012 time period. The number of filters to select was suggested to be 30 filters 

(plus one blank MTL filter). This represents approximately 1% of the entire 

population of ambient filters (excluding field blanks, lab blanks and collocated 

sites). It is suggested that the percent of samples must be in excess of the 

percent employed for acceptance testing to satisfy the requirement for a 

statistically valid sample. In reality, the actual number of affected samples is 

believed to be approximately 30 to 35% of the total filter population. 

Using the reduced number of filters thought to be affected (based on 35%), the 

number included in the study (30) represents 2% of the total population of filters.

In this case the number of filters selected is 2 orders of magnitude above the 

selection level considered acceptable for acceptance testing.

Year

All TN 

Sites 

Creditable 

Samples 3 Yr Avg

Filters 

for 

Special 

Study

Percent 

Filters 

Selected

Entire 

Pop. Of 

Filters 

2014

Filters 

for 

Humidity 

Testing

Percent 

Filters 

Selected

2010 4430 4263 30 1% 211,849 50 0.02%

2011 4237

2012 4122

35%

1492 30 2%
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3. What method will be employed to select filters to include in the study?

Only filters that were determined to meet the requirements for both pre and post 

laboratory conditioning and weighing were considered for acceptance and 

selection. Filters processed by the TDH weighing lab in Nashville during the 3 

most recent months of operation (November, December 2013 and January 2014), 

were evaluated to determine if they met the criteria and were not flagged by the 

lab or determined to be invalid or flagged for another reason. The filters that met 

the criteria were then assigned a number between 1 and 399 and a random number 

generation program was used to select random numbers within this specified 

range and matched the random number to a filter number in the data set. In this 

case field blanks were also included in the population of filters selected to draw 

the 30 filters from. The criteria employed to determine if the filters were 

representative of the filter population is met because 30 unaffected filters were 

identified as available. The candidate population of study filters was then shared 

with representatives of the 3 local programs (Knoxville, Nashville and Memphis) 

to determine if they were agreeable to using these filters to represent the entire 

population of filters, including the filters form their own sampling networks. All 

three agreed to use the selected set. If any of the local programs decided to 

nominate their filters to include, they would have to directly contact the TDH lab 

to arrange for their filters to be released as TDEC APCD does not have access to 

local programs filters as they are under separate contract with TDH for services.

4. What method will be employed to ensure that the contract lab is weighing the 

study filters in an unbiased manner?

In order to ensure that the filter weighing and processing is performed in an 

unbiased manner by the contract weighing lab, only filter numbers were provided 

to the TDH lab to use to retrieve the selected filters from storage. The TDH lab 

was instructed to ship the selected filters directly to the contract lab without any 

additional information about the previous weighing performed by the TDH lab. 

The filters were shipped according to the TDH labs expedited shipping protocol 

and following instructions provided by the contract lab. It is understood that the 

contract lab received the filters and immediately placed them into storage in 

preparation for the initial intake weighing to establish a baseline mass at normal 

temperature and humidity conditions established for PM2.5 mass weighing.

5. What will be the basis for determining if the level of difference noted in the 

contract lab reweighing of the filters is significant and can a simple test be 

performed to determine if this level of error is or is not exceeded?

In evaluation of possible levels of significance in differences in the mass of the 

filters being processed, it is critical to note the following levels of significance 

already recognized by EPA and included in the MQO table:
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Criteria Acceptable Range

Lot Blanks Less than 15 ug change between weighings

Field Blanks ± 30 ug change between weighings

Lab Blanks ± 15 ug change between weighings

Duplicate 

Filter 

Weighing

± 15 ug change between weighings

Lower 

Detection 

Limit

< 2 ug/m3

In evaluation of the values stated above, it becomes clear that if a field blank can 

vary by up to ±30 ug and still be acceptable, the implied variability in the field 

sampling results is also no more than ±30 ug. In taking this approach further, the 

lab blank variability may also be considered a reasonable guide to determine if 

results are in excess of acceptable weighing results. It is proposed that 

significance in the reweighing operations performed by the contract lab be 

defined as having an absolute net mass difference either in excess of the lab blank 

or field blank differences described. Values falling between the two stated 

numbers would be considered acceptable to the extent that these deviations in 

weights are normally assigned operational status event flagging and are 

acceptable to be reported to AQS with a “2” flag.

6. What are the other approaches being considered for filter recovery and 

revalidation?

The statistical review of the TDH lab measurement data for temperature and 

humidity indicate that a number of reported measurement values may be slightly 

over or under the stated control ranges for temperature and humidity (within 0.1 

% RH or 0.1 Deg C of the control temperatures and humidity’s specified by the 

method. It is understood that this special study will also reinforce any decisions 

made with respect to validation of the affected datasets at least up to the specified 

ranges included in the study.

Although not entirely applicable to this special study, the current DQO’s for PM2.5 as 

stated in the current TDEC QAPP approved by EPA for PM2.5 are stated as follows: 

“The ambient air quality monitoring program will establish an acceptable precision of 

±10%, as measured by coefficient of variation, and an acceptable bias of ±10%. By 

controlling precision and bias at these levels, the decision error probability limit will be 

5%.”

The relevant MQO’s (Measurement Quality Objectives) are defined in the following 

tables provided by EPA.

The following critical criteria tables define EPA’s expectations of the data quality and 

further clarify the requirements for the laboratory performance during filter processing 
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when weighing PM2.5 filters. The criteria of most concern with the laboratory weighing 

operations are identified by a black outline box to help separate them from the other 

criteria that may be related to field sampling and field equipment checks and quality 

assurance requirements.
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General Data Quality Objectives

For the purposes of this study, the same DQO’s apply for overall laboratory data quality with the 

understanding that the contract laboratory is not processing filters that have been collected under 

a 30 day expiration from sampling date window as would be the case with regular samples being 

processed coming in directly from the field. The same qualification applies for the requirements 

that the same weighing lab must perform both the pre and post weighing of the filters using the 

same balance. The filters being examined in the study are previously exposed filters and 

therefore are not subject to a pre-weighing requirement to obtain an unexposed mass weight.

Training Requirements

The contract laboratory is a recognized national laboratory and contracts with EPA and other air 

monitoring agencies in the provision of PM2.5 related gravimetric analysis services. See section 

A.8 of the QAPP for Chemical Speciation of PM2.5 Filter Samples, Revision No. 13, Date: 

January 27, 2014.

Documentation and Records

All of the data and summary reports generated by the contract lab will be provided in support of 

the study. If additional information is needed relative to the filter processing operations 

performed, including copies of any logs or other records generated, the contract lab will need to 

be contacted to supply them. See section A.9 of the QAPP for Chemical Speciation of PM2.5 

Filter Samples, Revision No. 13, Date: January 27, 2014.

Sample Custody Procedure

For this study, a filter list was developed based on random selection of filters processed by the 

TDH PM2.5 weighing lab and identified as meeting the laboratory QC requirements for 

temperature and humidity control during pre and post filter weighing operations. These filters 

are considered to be valid and “un-flagged” filters that will be reported to AQS “as is” 

representing actual air quality. The list of filter numbers was provided to the TDH labs to pull 

from the filter storage archive of recently collected filters and ship directly to the contract lab. 

The contract lab was not provided with any TDH weighing information or data associated with 

the filters and the only identifying information provided was the actual filter number embedded 

on each filter as supplied by the MTL filter manufacturer. See section B.3 of the QAPP for 

Chemical Speciation of PM2.5 Filter Samples, Revision No. 13, Date: January 27, 2014. Filters 

will be returned to the TDH laboratory for archive and storage.

Analytical Methods Requirements

Standard Operating Procedure for Particulate Matter (PM) Gravimetric Analysis, PM 

Gravimetric Analysis, Revision 9, Date: July 8, 2008. Contractor SOPs have been updated 

annually, but they are not public documents until EPA posts them at the beginning of a new 

contract. SOPs following the analytical method requirements were adhered to for this study with 

robotic weighing using the MTL AH-225 Precision Weighing System.
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Quality Control Requirements

The laboratory SOP’s employed by the contract lab is included and identifies the QC 

requirements and methods employed by the contract lab to ensure these requirements are being 

met. The laboratory utilized a robotic weighing system with excellent precision capabilities to 

follow the quality control requirements. See section B.5 of the QAPP for Chemical Speciation 

of PM2.5 Filter Samples, Revision No. 13, Date: January 27, 2014 and Standard Operating 

Procedure for Particulate Matter (PM) Gravimetric Analysis, PM Gravimetric Analysis, Revision 

9, Date: July 8, 2008.

http://www.epa.gov/ttn/amtic/files/ambient/pm25/spec/qapp.pdf

http://www.epa.gov/ttnamti1/specsop.html

Equipment Acceptance Testing and Maintenance

The contract lab must be capable of performing normal PM2.5 filter weighing activities and also 

meet the study criteria extremes for both temperature and humidity. The contract laboratory was 

initially contacted to determine if their weighing facility could meet the following humidity and 

temperature control levels for testing purposes

Humidity Extreme

Range % Humidity Control

Low 25  5% SD* over 24 hr.

High 45  5% SD* over 24 hr.

Temperature Extreme

Range Temperature °C Control

Low 18  2

o C SD* over 24 hr.

High 25  2

o C SD* over 24 hr

After undergoing tests for both temperature and humidity, the contract laboratory was able to 

meet and maintain the specified levels of control relative to the low and high extreme ranges 

specified. The contract lab also indicated that these levels were able to be maintained during the 

weekend weighing periods set aside for the study filter processing including both conditioning 

and actual weighing. See section B.6 of the QAPP for Chemical Speciation of PM2.5 Filter 

Samples, Revision No. 13, Date: January 27, 2014.

Instrument Calibration

All laboratory analytical equipment must be periodically calibrated with weighing lab equipment 

referenced to NIST standards. See section B.7 of the QAPP for Chemical Speciation of PM2.5 

Filter Samples, Revision No. 13, Date: January 27, 2014.
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Requirements for Supplies and Consumable

Although the contract lab is not responsible for providing the blank filter media for actual field 

sampling, section B.8 of the QAPP for Chemical Speciation of PM2.5 Filter Samples, Revision 

No. 13, Date: January 27, 2014 specifies how these items are obtained.

Acquisition of Data

The study undertaken by the contract lab does not require any data acquisition from historical 

sources. The filters provided are all pre-numbered with the numbers being supplied by the filter 

manufacturer. No filter mass weighing data from the previous labs weighing activities was 

provided for the filters employed in the study.

Data Storage and Management Activities

The contract laboratory will be responsible for all data management activities and will process 

and store the data generated directly by the weighing instruments as electronic data files. See 

section B.10 of the QAPP for Chemical Speciation of PM2.5 Filter Samples, Revision No. 13, 

Date: January 27, 2014.

Data Validation

Processing of the exposed filters for this study involves the use of filters that have already been 

used for PM2.5 air sampling and have subsequently determined by the TDH lab and the TDEC 

APCD to be valid acceptable unflagged filters. See section D.1 of the QAPP for Chemical 

Speciation of PM2.5 Filter Samples, Revision No. 13, Date: January 27, 2014 for the procedures 

employed by the contract lab in typical data review and validation. The filters processed in this 

special study are not able to be subjected to review which includes the typical field and other 

related data elements as these elements were not made available to the contract lab. The data 

resulting from the special study weighing evaluations will not be employed to directly calculate 

or generate a data value to be loaded to AQS and therefore will not be required to be calculated 

to render an ug/m3 value. However, it is anticipated that the results will be used to specify 

whether existing data already loaded to AQS may be voided, flagged or annotated to convey 

unusual or out of the ordinary conditions associated with the affected filters.

Final Data End User Requirements

The special weighing study is not intended to be an on-going laboratory function and as 

described previously in this document, is designed to examine weight differences found under 

extremes of temperature and humidity outside of the normal PM2.5 weighing labs accepted 

ranges of temperature and humidity. The contract lab will provide a draft study report detailing 

the preliminary results from the weighing investigations undertaken and in coordination with 

TDEC APCD address comments pertinent to preparation of the final study report.