United States Office of Air Quality EPA-4541D-94-001 

Environmental Protection Planning and Standards September 1994 .. 

Agency Research Triangle Pnrk, NC 27711 

Air 

GUIDELINE ON THE 

IDENTIFICATION AND HANDLING 

OF AMBIENT AIR QUALITY DATA 

AFFECTED BY SPECIAL EVENTS OR 

SPECIAL CONDITIONS 
DRAFr - 9/8/94 

EPA 4541D-94-001 

GUIDELINE ON THE IDENTIFICA,.TION AND HANDLING OF AMBIENT AIR 

QUALITY DATA AFFECTED BY SPECIAL EVENTS 

OR SPECIAL CONDITIONS· . 

1.0 INTRODUCTION 

1.1 Purpose and Contents 

1.2 Background 

1.3 Changes Necessitated by the 1990 Clean Air Act Amendments 

2.0 DATA USAGE, TESTS, CRITERIA 

2.1 Uses of Flagged Data 

2.2 Special Events and Special Conditions 

2.3 Qualifying Tests 

2.4 Supporting Criteria and Documentation 

3.0 FLAGGING PROCEDURES 

3.1 Data Flagging System 

3.2 Submission of Supporting Documentation 

3.3 Concurrence and Review Flags 

FIGURE 3-1 Process Flow for Selecting and Applying 

A Data Flag 

FIG URE 3-2 Flow Chart for the Data Flagging Process 

TABLE 3-1 .. Time Requirements for "T" Flags 

ArrE\"nIX A Listing of Descriptor Code Options 

AI'I'E\"D1X II Listing of Events Not Eligible For Approval 

as Special Events 

AI'I'E'iIllX C Listing of Acronyms 

RFFERE'iCES 

IiI." ,f,', I~".nl" 't'/I/,J, ('\ rlu' (;IIIt/('/tnt' nn till' /dell/lIIira/inn and Use of Air QUll!in' Data Affected by Exceptional 

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1.0 INTRODUCTION 

1.1 Purpose and Contents 

The purpo.se o.f this document is to. pro.vide guidanceo.n the procedures fo.r flagging and 

reporting of data associated with various circumstances: data validation, the submittal of 

informatio.n related to data, and/or request for special treatment accompanied by supporting 

dotumentatio.n. related to. an event or conditio.n. In summary, this document co.ntains the 

following: 

Chapter 1 provides a brief explanation of the history of special event data flagging and 

an introduction to this document. 

Chapter 2 presents data usage, tests, and the criteria used to determine if a data value 

can qualify fo.r the attachment o.f a data flag. 

Chapter 3 provides info.rmation o.n the procedures to. be fo.llo.wed fo.r flagging data and 

providing SUPPo.rting documentation fo.r flags. The review process that the U.S. 

Enviro.nmental Pro.tection Agency (EPA) will co.nduct is briefly described and examples o.f 

appropriate supporting documentatio.n are listed. 

Appendix A provides an explanation o.f several categories o.f events and co.nditions that 

_~; ____ • _.~ _____ ma},-be_.used_to_describe_many_types_of_circumstances-affecting-data-values,---1'his-lisHs-------------

based on the list o.f exceptio.nal events defined in the Guideline o.n the Identificatio.n and Use 

of A ir Duality Data Affected by Exceptio.nal Events (EPA-450/4-86-007, July 1986, hereafter 

referred to. as the 1986 Exceptio.nal Events Guideline),l with mo.dificatio.ns to. include several 

events and co.nditio.ns which were no.t in the o.riginal guideline. It is impo.rtant to. no.te that 

thi., list is not exhaustive: it is intended o.nly to. pro.vide descriptive info.rmatio.n about certain 

cnnlilll!ln, that have been enco.untered by vario.us Statellocal air quality mo.nito.ring and 

rcr"rttn~ J!!encies (hereafter referred to. as "repo.rting agencies") in past data-flagging 

CxpCfll·nccs. 

I\ppcnliix B pro\"ilies examples of events that sho.uld no.t be co.nsidered as special events 

\\;lrfalltll1~ specIal treatmmt of data. Generally. these examples do. no.t meet the basic 

crlll'rt.1 th;!l W!luIJ support J special event claim. 
. Appendix C provides the reader with a list of acronyms used in this guidance 

document. 

1.2 Background 

The 1986 Exceptional Events Guideline established procedures for the flagging and 

treatment of monitoring data affected by exceptional, or nncontrollable, events. This 

guidance was intended to provide State and local officials with assistance in identifying data 

that.were believed to have been influenced by the occurrence of certain specified natural 

ev6nts .. Authority for this approach is set out in Appendix K of 40 Code of Federal 

regulations (CFR) part 50. The 1986 Exceptional Events Guideline mainly focused on 

problems relating to PM-I0 (particles with an aerodynamic diameter less than or equal to a 

nominal 10 micrometers) monitoring data, but provisions for flagging data from the other 

criteria pollutants were also included. The need for this guidance grew out' of a history of 

concern by States over EPA's treatment of monitored data. 

Through the late 1970s and early 1980s, certain air quality data obtained by monitoring 

stations in various States were not submitted to the EPA's National Air Data Bank (NADB) 

as then required, due to concern on the part of State and local air pollution officials that the 

. data. if used, would unfairly represent the air quality problems in their areas. The data in 

question were not considered to be representative of atmospheric conditions by these officials 

and in their view were atypical readings attributable to special events that warranted special 

tn:atment for the data by EPA. 

Concern by the States over EPA's use of data affected by special events began as early 

as h:oruary 1977, when the Office of Air Quality Planning and Standards (OAQPS), in its 

GUideline for Intemretation of Air Ouality Standards included this statement: "[RJegardless 

01 th,' ~uum:. ambient pollutant concentrations exceeding a National Ambient Air Quality 

StJlld.trd (:-->AAQS) constitutc a violation ... 1 However, even then, the OAQPS guideline 

11l1rl'I'J thc nced for a flagging systcm to identify data affected by exceptional events when it 

\IClll ,'II I,' ~Iatc that "detailed infomlation cstablishing that violations due to uncontrollable 

ll.llul.1i ,,'urcc~ may Ix: u~cd in dctcmlining the feasibility of modifying control strategies." 

1.111'1. IL·~ul.lIl<lll~ promul!!ated by EPA regarding the development, adoption, and submittal 

ul "I.,IL' IIlIpiclllclitall(ln plans (SIPs) staled in 40 CFR part Sl.llO(f)l that "for the purposes 

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of developing a control strategy, data deri~ed from measurements of existing ambient l~vels 

of a pollutant may be, adjusted to reflect the extent to which occasional natural or acCidental 

phenomena ... demonstrably affected such ambient levels during the measurement period. " 

Treatment of data influenced by special events was also addressed in EPA's'March 1984 

proposed revision to title 40 CFR part 50 (revising the NAAQS for particulate matter from a 

total suspended particulate (TSP) to a PM-IO standard). The proposed revision, which was 

pro~ulgated on July 1, 1987 (52 FR 24663)\ included provisions in Appendix K that allow 

States and EPA to consider the influence of rare or unusual events on PM-IO monitored data. 

Section 2.3 of Appendix K Specifies that all data collected in accordance with the 

minimum PM-lO sampling requirements of 40 CPR part 58 should be used when making 

comparisons to the NAAQS. However, section 2.4 of Appendix K allows EPA to consider 

whether to discount or weight the effect of ambient air monitoring data for PM-IO influenced 

by exceptional events, That section notes that 'inclusion of (data from such events) in the, 

computation of exceedances or averages could result in inappropriate estimates of their 

expected annual values." Section 2.4 gives EPA discretion to consider more than 3 years of 

representative data, or to consider other adjustments, as appropriate in order to "reduce the 

effect of unusual events." This discretion is normally exercised by the appropriate Regional 

Administrator, in accordance with published guidance, 

~~-:r:he-1986 EXGept-ional-Events.Guideline-was.intend€:d.lo.assist-EPA,State-and-looaII~~~~­

of(-Icials in ensuring that air quality data associated with special events are given appropriate 

special handling to prevent misuse when calculating expected annual values. The EPA's 

general policy. as summarized in that guidance, was to consider excluding flagged data from 

usc in regulatory actions, This policy specifically did not create a presumption regarding the 

me or non-usc of such data. hut rather was intended to offer a forum for States to present 

1:1':\ with documentation supporting a request for exclusion of reported data from use in 

rc~ul:it.,r\ actions, By estahlishing uniform procedures for flagging such data, EPA hoped to 

11I1rr, \\ c tlata suhmission and estahlish a consistent decision-making process for the use of the 

tl;tt.1 lI.,wc"cr, in practice, this process has often resulted in an erroneous belief that State 

alld I,,,al "Iflclals could automatically exclude all flagged data from regulatory actions. It is 

iInportant (o~qaie here thai t1a!!W!! of data does not, bv itself, result in the exclusion of 

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such dota from regulatory decision making. Rather. flagging is lUI important prerequisite 

to consideration of whether or not to grant such exclusion. 

Since the issuance of the 1986 guidance, EPA's data storage and retrieval system has 

been replaced by a new comprehensive air quality data system known as the Aerometric 

Information Retrieval System (AIRS), Air Quality Subsystem (AQS)5. This improved data 

collection, storage, and retrieval system is EPA's system for collecting, flagging, and 

retrieving affected data under the procedures outlined in this document. This document, . . 

Guideline for the Identification and Handling of Ambient Air Qualitv Data Affected By 

Special Events or Special Conditions (hereafter referred to as the 1994 Special EVents 

Guideline), describes the procedures for the flagging and reporting of data associated with 

various circumstances: data validation, the submittal of information related to data, and/or. 

request' for special treatment accompanied by supporting documentation related to an event or 

condition. 

1.3 Changes Necessitated by the 1990 Clean Air Act Amendments 

Passage of the Clean Air Act, as amended in 1990 (the Act), necessitated the review of 

a number of existing EPA regulations and guidelines. Guidelines on flagging of data affected 

by special events, including the 1986 Exceptional Events Guideline, are significantly affected 

by the addition of PM-1O specific provisions in section 188(f)(subpart 4 to part D of title I) 

in the Act." This new section of the Act authorizes the Administrator of EPA to waive, on a 

case-ny-case basis, certain provisions applicable to serious nonattainment areas for PM-1O 

and a specific attaihment date for moderate and above PM-1O nonattainment areas. The 

exerci~<.' of this waiver authority by EPA is predicated on a determination that anthropogenic 

s(\urces of PM- \0 do not contribute significantly to the violation of the PM-1O NAAQS in the 

,m:;1 A specifiC attainment date may be waived if EPA determines that nonanthropogenic, or 

mtuLII. s"urces of pM-IO contrihute significantly to the violation of the PM-IO NAAQS in 

the .lre.1 The EPA polk)' and guidance on the exercise of the section 188(f) waiver 

auth"rll\ " ;IJdressed in an EPA publication including serious area and other PM-IO 

1l,'II.III,IIlIl\1el1l requirements. lIowever, the major implication of section 188(f) for the 

Il""~"lc ,,' J.lla I' that 11<1\\ all valid measurement data are expected to be used in the 

Je"CIl.III"1l ,,' all'area a, attainment or nonattainmcnt and that adequate documentation is 

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provided to support any related flags that are attached to reported data. 

The resulting review of the applicability of the 1986 Exceptional Events Guideline ,has 

led to this new guidance document which establishes revised procedures for identifying and 

handling ambient monitoring data that may be influenced by special events or special 

conditions. New procedures are introduced for flagging any data value, whether below or 

above the NAAQS, as valid or requiring explanatory documentation. Consequently, this 

document hereby replaces the 1986 Exceptional Events Guideline document. While the .. 

majority of the changes in this revision apply specifically to the treatment of particulate 

matter data, there are some revisions to event descriptions that apply to the handling of data 

for other criteria pollutants .. Data for pollutants other than PM-I0 that were eligible for 

special treatment under the 1986 Exceptional Events Guideline continue to receive such 

consideration under this revision. It is important to note that although the procedures for 

handling such data are subject to many of the same changes as apply to particulate matter 

data, the section 188(0 waiver provisions are specific to PM-lO. 

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2.0 DATA USAGE, TESTS, CRITERIA 

2.1 Uses of Flagged Data 

Monitoring data have many uses. Identifying air quality trends and providing air 

quality information to the public or the scientific community are uses meriting data flagging 

and are not intended to result in regulatory relief from the effects of data influenced by 

special events or special conditions. 

The use of data to make NAAQS comparisons and in conducting SIP regulatory 

activities are subject to legislative and regulatory limitations. Comparisons of monitoring 

data to the NAAQS are controlled by section 1l0(a)(2)(B)(i) of the Act and procedures for 

making such comparisons are contained in 40 CFR part 50. This document does not 

specifically address the procedures for analyzing the impact of flagged data on policy 

decisi()ns and other SIP activities for PM-IO. 

Not all situations meriting data flagging are intended to result in regulatory relief from 

the effects of data influenced by special events or special conditions. Data submitters may 

simply wish to provide potential data users with an indication that additional infonnation is 

availahle on a particular data1;et._Ihis-can_be_accomplished-by-f'lagging-the-data-set-and------

suhmilling the explanatory infonnation. Data flagging allows the data submitter to 

. supplement a data record with useful.infonnation that can enhance the use of the data for 

such non-regulatory purposes. 

Appendix K to 40 CFR part 50 specifies that all data that are collected under the 

prnccdun:' contained in 40 CFR part 58 should be used when comparing an area's air quality 

tn tile' ~ :\t\QS. Prohlems arise. however. when data are interpreted and acted upon without 

a etc;,r lllldcrq;mding of the circumstances and conditions under which they were collected. 

It " l1o,t UllL'''IlII1HlO for two or more interpretations to be possible when examining ambient 

all co"kCIIlr;II1<'1l data affectcd hy s['ecial events or special conditions. In such instances. it is 

([ltk.1i til.,1 ;,Jultl(\l1al infllmlatinll he a\'ailahle for use in shaping the conclusions on which a 

rC~lll.'to'n .'-\'''11 will he hascd since (lnly one interpretation can he given legal effecl. 

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Flagging procedures allow the data submitter to mark a data value(s) in a way that , ' 

, . refers the data user to additional information that might influence its(their) use. Such 

additional information might be used to support claims that data have been unduly influenced 

by an event or condition such that special regulatory handling of the data is' warranted. For 

instance, if an area's concentrations of PM-IO result in its designation as a nonattainment 

area, that area will be required to meet certain control requirements. If, however, it can be 

demonstrated that the PM-lO exceedances were the result of emiSsions from an event that is 

noi likely to recur, then it'may be possible to avoid the area's designation as nonattainment 

altogether. For PM-lO, this is permitted by Appendix K to 40 CFR part 50. Flagging such 

data for special consideration when making comparisons to the NAAQS can achieve this end. 

The EPA would make any such determinations in accordance with the procedures contained 

in this guideline. 

2.2 Special Events and Special Conditions 

There are a number of situations in which a data flag may be applied to request 

regulatory relief. Some of these scenarios are described in Chapter 3. They may be 

categorized as either special events or special conditions, depending on surrounding 

circumstances and supporting information. They may also be characterized as anthropogenic 

(or manmade) or nonanthropogenic in nature, subject, again, to review of supporting 

documentation. 

FACTOID 

.... pedal el'ents are discrete occurrences. either anthropogenic or 

/I(lnontlzropogenic. that can be classified as not likely to recur. 

Special conditions are well-documented circumstances that can have a significant 

II/flumc£' on the ambient concentrations of a pollutant and are of a recurring 

/I,I/llr(', Tl1l"Y may resull. for inslance. from anthropogenic emissions originaling 

,,./1111 (lur,I/I/e of Ilze Uniled States. or nonantirropogenic emissions. such as wind 

"'.,\\ 1/ dllsl from a nonanthropogenic source. 

Iii C'1'1\ l'r.t!, LI'A npcC:l' to exclude data intluenc:cd hy special events and which qualifJ 

1"1 d,IL, 11."·~111~, Irtlill L'(l!1lpanson with the NAAQS, l3y excluding the data. EPA hopes to 

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avoid situations in which data that are not representative of an area's expected air quality are 

used to dictate control requirements and Strategies for that area. 

Data resulting from events that are likely to recur or from special conditions will not be 

eligible for exclusion from NAAQS comparisons. However, forPM-lO values associated 

with special conditions, such data may be used under section 188(f) to support a request for a 

waiver of serious nonattainment area control requirements or specified attainment dates 

should the area meet the waiver policy criteria. Section 188(f) refers to, among other things, 

norlanthropogenic sources.· Thus, events caused by nonanthropogenic emissions that are 

likely to recur and special conditions, as defmed in thiS Section, will no longer be eligible for 

exclusion from NAAQS comparisons. (Note that the 1986 Exceptional Events Guideline had 

implied' that all events caused by nonanthropogenic emissions would be considered 

"exceptional events", thus eligible for exclusion from NAAQS comparisons.) 

2.3 Qualifying Tests 

This section presents the tests that must be applied for data to qualify for the attachment 

of a special event data flag. The data flags that simply validate the data value, or indicate 

the availability of additional information on the data value may be applied without 

"qualification". Supporting documentation for potential special events must address the 

following tests: 

FACTOID 

Recurrence Test: 

The event's likelihood of recurrence. 

Culpability Test: 

The causal relationship between the event and the measured air quality 

dota. 

The ICrIll "likelihood of n:currence" cannOI he absolutely defined so that there is no 

f<\(\111 1< 'f 1I11erpn:lalion. Whal may he considered a special event fOf one part of the country 

mal Ix: Il"rlG!1 1m another. Ii is obviously impossible to predict future air quality events, 

Ihcrel>'fe. Ihe "likelihood of recurrence" will he based on historical information. It is the 

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reporting agency's responsibility to collect, review, and submit appropriate historical data 

and information to sufficiently support and advance their claim that the event is not illcely to 

recur and a causal relationship between the source of the event and the data value(s) has been 

established. 

In order to promote consistency in the process, however, the following general 

boundaries are recommended when evaluating information' in support of the Recurrence Test 

and the Culpability Test. Generally, for all events, the reporting agency must use a 

mihrrnurn of five years of historical information when establishing the likelihood of 

recurrence. Special event documentation should be baSed on the most recent 5 years for 

which information is available. The reporting agency must work with the Regional Office 

for cases where five years of historical information (i.e. meteorological data) is not available 

to determine if the likelihood of recurrence may be based on the merits of what .is available, 

If an event occurs once in the five year period (i.e. the event in question is the first 

such occurrence in five years), then the event should be considered as not likely to recur. 

This scenario satisfies the Recurrence Test for the attachment of a special event data flag. 

The Culpability Test for the causal relationship between the event and the affected air 

quality data must be based on the following: 

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Consideration of all relevant raw data, such as air quality data, meteorological 

data, and traffic counts, etc.; 

A demonstration that the monitor did not report similar pollutant concentrations 

(or chemical constituents of particulate matter) before and after the time period in 

question; 

• Evidence that the wind speed and direction at the time period in question were 

such that the pollutant was transported from the source to the monitor reporting 

the data during the time period in question; 

• Appropriate modeling and/or filter analysis data as specified by the criteria in 

S<:<:tion 2.4. 

Ii " Imponant to note that while arplying a special event flag to the data set is 

t;II1t;lI1hlllllt til applying for sp<:cial treatment of the data, only EPA's acceptance of the causal 

rl'i.llIlllhlll[' ~<:(wccn a qualifying event and the data values and the evaluation of a recurrence 

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claim will result in that special treatment .. 

Although objective criteria are applied whenever possible, there is an unavoidable 

degree of subjectivity associated with the interpretation of the impact of special events and 

special conditions. Consequently, the review of any supporting documentation and the fmal 

decisions regarding the use of flagged data will be the ultimate responsibility of EPA 

Regional and Headquarters Offices. 

2.4Supporting Criteria and Documentation 

.' In order for EPA Regional and Headquarters Offices to make fmal decisions regarding 

the use of flagged data, it is extremely important that reporting agencies support flag 

applications with all appropriate documentation to create as complete a recounting of the 

event or condition as is practicable. Therefore, the criteria outlined below are intended to 

promote consistency in the submission of supporting documentation and data management by 

the reporting agencies and EPA. The process of flagging data by event type,as done prior 

to this guidance, is being replaced by procedures for the flagging and reporting of data 

associated with circumstances including: data validation, the submittal of information related 

to data, and/or request for special treatment aci:ompanied by supporting documentation 

related to an event or condition. Descriptive codes,derived in part from the list of events in 

the 1986 Exceptional Events Guideline, may be used to provide descriptive information about 

the nature of the evenLOLCQndition~Cbapter--3-contairu;-fuFth(W-inf0Fmilli0n-0n-the---------­

dcscriptive codes. 

There are six basic types of criteria that may apply individually, as appropriate, to the 

cvents or conditions in question to support their eligibility for special treatment or handling. 

/{ep(ming agencies should examine the circumstances surrounding the collection of a data set 

I{I en,un: that the applicable criteria have been documented before attaching a flag to the data 

'L"I S,'me criteria may apply to the majority of the events or conditions, while others may 

;Irrh I.' (lnly a few. The qualifying criteria used to document a potential special event must 

1'1' 'utlJ.:IL'nl to determine that the event is not likely to recur and should establish a causal 

rL'i.III"Il,IlIl' ~Iwecn the source of the event and the data value(s), The criteria options are 

a,I(,111 1\\' 

• \Irtl"orulog)' Criterion - Meteorological information may be used to indicate the 

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upwind versus downwind conditions or defmed wind speed and wind direction at 

the time and location of the event or condition relative to the monitor. This 

criterion is particularly but not exclusively important when evaluating events or 

conditions that occur within a rnicroscale, a middle scale, or neighborhood scale8 

from a monitoring station. 

• Modeling Criterion9 - Conclusions may be supported by dispersion or receptor 

modeling. 1bis criterion is often used for those types of events or conditions that 

occur at some distance from a monitor, generally over regional or urban scale 

dimenSions (>4 km)8: 

• Filter Content Criterion - A significant percentage of the monitor filter media 

content must be attributable to the event or condition. In general, EPA believes a 

significant contribution from a particular event or condition would constitute 85 % 

of the material on a filter. For certain events or conditions, deviations from this 

general 85 % guideline may be necessary and should be agreed upon mutually by 

the reporting agency and the EPA. The EPA and the reporting agency may also 

agree that filter analysis is not necessary for a particular event or condition if 

other supporting documentation clearly establishes a source-receptor relationship. 

When it is not possible for a reporting agency to successfully document the event 

using filter analysis, the reporting agency should notify EPA in its supporting 

documentation. It is recommended that filter analysis take place within six months 

immediately following the data collection date. This will minimize the possibility 

of damag ing or losing the filter. 

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Monitor Proximity Criterion - The event or condition must occur within some 

dIstance from the monitor as defined by the appropriate measurement scale as 

related to the monitor location and the event's source. The monitor proximity 

cnlerinnis used with most event types to document the source-receptor 

r<:lall'Hl~hip. Like the meteorological criterion. this information is particularly 

11lIp"rtalll fm e\'ents or conditions that occur within a micro-, middle, or 

'I<.·,~hh"rh(\(ld scale distance (0-4 kilometers) from a monitoring station. 

Tilll!' Criterion· Two types of time criterion may he used to document a 

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potential special event or special condition. The first of these would state that the 

questionable data was collected within some specified time during andlor" after the 

event or condition. This time requirement would be used to establish a sourcereceptor relationship between the data and the event or condition. A second type 

of time criterion considers duration, where, after a limited period of time the 

event or condition is no longer considered special. This second time criterion 

would be nsed, for example, to document the temporary nature of an event and to 

demonstrate the likelihood of recurrence of events. 

• Quantitative Criterion - Some numerical parameters may be applied to illustrate 

the size and nature of an event or condition. 

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3.0 FLAGGING PROCEDURES 

3.1 Data Flagging System 

A data flag is an identifying mark applied to any data value that indicates the 

availability of additional infonnation describing the causes of, or circumstances surrounding 

the collection of, the data value, Three types of data flags can be used by the data reporting 

agency as listed below: 

.... Se(;i!oh.2,.~)'The~. ~.~. !. !~~~!!II iuidiiiiinaUi!tormationon a ~~~,.,~~;~,jfm '(siiis&fii8ii3.2). [((Shortt .. 

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affected.by potential.speqigieveflls. y . :":')',. "}:JMi}!.·, t/?{;t 

2. Validity "V" Flag - tojrifJicliilihhtadJili ··"·';)~.ilA~h;;;i;;t; 

validated by the reporting agency. " ; .. 

various reporting agencies with data values that exceed thel:{AAQS. 

3. Treatment "T" Flag - to notifY. EPA olthe re]lQ11ingJlgency-'-:LinlenLto_seek _____ _ 

relief from certain regulatory requirements resulting from the affect of a 

potential special event (see definition. Section 2.2) on the data value(s). 

Application of a Type T flag indicates that supporting documentation will be 

submitted by the reporting agency to justify any relief sought. Application 

of a Type T flag must be made within 30 days after the end of the reporting 

period. (The reporting period for National Air Monitoring Stations (NAMS) 

or State/Local Air Monitoring Stations (SLAMS) ends 90 days after the end 

oj the calendar quarter in which the data value occurred. For Special 

Purpose Monitors (SPMs). this reporting agency is generally required to 

rl'{JOrt all data. with appropriate T flags. by July I of the year following the 

rear in which data were collectedw) 

l'nli~e Jaw with Type T nags, Jata values with Type lorY nags are not related (0 the 

. occurrencc' 01 a ~recial C\'en! [)ata values with a Type V nag would, therefore. be used 
without special treatment for regulatory purposes and may be submitted to AIRS-AQS at any 

time. Data values with a Type I flag indicate the availability of additional informati6n for 

conducting scientific analyses, documenting circumstances worthy of note, or ensuring that 

data relevant to exercising the waiver provisions in section 188(f) for PM-lO are properly 

represented. 

Applying a Type T flag to a data set signals the reporting agency's intent to seek relief 

from certain regulatory requirements resulting from the effects of a potential special event. 

WIi.en special treatment of data is requested by the reporting agency, it must be supported by . . additional information in the AIRS-AQS descriptor fields showing the nature of the event. 

This supporting m:i,terial can include information on meteorological conditions, filter analysis 

results, and other information as described in Section 3.2 of this document. 

It is important to understand that no assumption can be made on the ultimate disposition 

of the data until the documentation has been received, reviewed, and any request for special 

treatment approved by EPA. It is not EPA's intent to remove all subjectivity from the data 

flagging process. Ongoing communication between the data collecting agency and the 

appropriate Regional Office are critical during determinations of applicability of data flags 

and the ultimate disposition of flagged data. 

The procedure for determining the appropriate flag to apply to a data set is ilIustrated in 

Figure 3-1. 

3.2 Submission of Supporting Documentation 

Supporting or explanatory documentation may be submitted for many applications, 

Reporting agencies may elect to submit explanatory documentation for any data value, 

Timely ~uhmittal of information relating to any flag is recommended so data users will have 

'Ieees,s III explanatory information for flags as soon as is practicable. 

When the documentation is suhmitted to support a contention that a special event 

lu,tlllc" 'pccial treatment of air quality data. two tests must be addressed in the 

d,,-'UI11L'I1t:III(ln: Test 1: the event's likelihood of recurrence, and Test 2: a causal relationship 

kl" L'c'l1 thc' 'rcclal event and the measured air quality data, These qualifications must he 

c'I.II'I"hL'J III CIllketin): Inlllnnation from all availahle sources to create as complete a 

rL""UIlI"I~ "I thc c'\'Cnl anJ II' effects as is practicahle, 

14 

; 

, 

, 

, 

\ i 
In order for reporting agencies and EPA to reach timely closures, on the review of 

special event flags, time requirements identified in this document must apply to Type'T flags. 

Data values for PM-lO resulting from special conditions may be associated with an 

area's request for waiver of serious nonattainment area control requirements or specified 

attainment dates should the area meet the section 188(0 waiver policy criteria (see Section 

2.2). Therefore, it is recommended that the time requirements for the submission of 

supporting documentation be applied for data values associated with Type I flags for special 

cortditions. This recommendation is only meant to assist reporting agencies in keeping track 

of the information that may be useful in supporting future applications of waivers under 

section 188(0 of the Act. 

Supporting documentation for potential special events must be submitted to the Regional 

Office within 60 days of the T flag submittal period. The only exception to the requirement 

to submit special events supporting documentation to the Regional Office is for special events 

caused by stratospheric ozone intrusion. In those cases, the OAQPS has the responsibility 

for reviewing';.the affected ozone data, the special event documentation, and the subsequent 

concurrence/non-concurrence actions. As such, the reporting agency should send supporting 

documentation for stratospheric ozone intrusion affected data to the OAQPS in addition to the 

Rc!!ional Office. 

, ''---~---[-)H€u,m~nta~i0n-and-analyses.csupp()rting-the-appHcation-of-a-flag-to-a-candidate--event o"'t------

C!lntllUon includes, but is not limited to, news reports, meteorological records, work 

sdwduks. PM-IO filter analysis, and other supporting documentation establishing the event 

In question as a matter of public record. It is generally preferable to provide some 

Inl •• nnat Hln of this type to the AIRS-AQS electronically, where it can be directly linked to 

tli~ Ila~~ed data set through the use of it's data descriptor fieW. In cases where this is not 

1" "'It-Ie, IIil: supporting documentation may be submitted to EPA in hard copy form, 

• "'·I\,·nlll~ a~"nci"s should ensure that hard-copy documentation is carefully referenced in the 

.1)'1'" 'I" 1.lie· :\ IRS "QS data descriptor field.) 

\ II .. JJ IIHlna I lkscriptor code, inputted within the AIRS-AQS descriptor field, must also 

k Ilk IlJ,kJ I .. ;dl"" 1m d;lIa sorting amI other retrieval options, These codes are used to 

",,!!. .. :,' 1111: 1I.IIUr': "I Ihl: sJ1Ccial event or special condition. A listing of these descriptor 

15 
code options is included in Appendix A. 

Examples of the types of public and technical infonnation that may be used to support 

and advance claims of data influenced by a special event or special condition are discussed 

below. As stated above, reporting agencies may elect to submit public and technical 

infonnation explaining any data value, not just those associated with potential special events 

and special conditions. (Public and technical infonnation may provide the background for 

the brief written summary of event or condition circumstances that may be included in the 

free-form comment fields associated with the flagged data set's descriptor field.) 

1. Meteorological reports - These reports would be used to substantiate the meteorology 

criterion and could be included in any modeling requirements that may be necessary. 

Meteorological information is generally helpful in determining a causal relationship 

between an event or condition and a certain data value(s). 

2. Particulate matter filter analysis - Results from the fIlter analysis would be used to 

substantiate the fIlter corttent criterion. Analysis of fIlters collected before and after an 

event .or condition may be used to support it's occurrence claim. Some examples of 

circumstances that would normally require a filter analysis include high winds, high 

pollen count, long-range pollutant transport, sandblasting, construction/demolition, 

agricultural tilling, highway construction, and salting and sanding of streets. 

3. \"('ws reports, photographs, and videos - News reports, often accompanied with 

ph(ltngraphs and/or video, are used by the media to illustrate the severity and scope of 

an event or condition, particularly if it effects a large population center or land mass, 

hents and conditions that may be recorded through news reports, photographs, and/Or 

\ IdL'o, include high winds. volcanic eruptions, forest fires, high pollen count, 

"<Instruction/demolition. rerouting of traffic, highway construction, infrequent large 

""lhL'fIn~\, industrial upset conditions. structural fires, sandblasting, salting/sanding of 

'i'L'l'ts. r"('lin~ operations. and prescribed burning, Aerial or satellite photographs may 

,d, ' t><: u'ed III analysis of long·range pollutant transport. 

-\ :O-d,'ntifi(' Clhwnations. scientific journal articles, seismic reports - Scientific 

,,10'('[\,111<'11' and an:II\'\e.\ are required to determine if an event or condition is the result 

,,' 'ir,II<"i'IlCTIL' ",one Intrusion and long-range paHutant transport. The size and 

16 

i : 

'---J 

. 

, 

! ; 

• i 

; f 

i ' 

: ! 

i ; 

! ; 

i ' 

I 

i ~ i . , , 

, . • ! 

j" 

; f 

i ' 

I 
severity of volcanic eruptions may be illustrated by records of seismic activity in 

addition to scientific observations. 

5. Operating permits .and work orders - Operating permits and work orders are often 

examined when a reporting agency is evaluating events or conditions involving 

anthropogenic sources. The reporting agency must document compliance or 

noncompliance with permit conditions and control requirements. Events which are most 

likely to involve the examination of a source's operating permit and/or work orders 

include sandblasting, construction/demolition, highway construction, traffic rerouting, 

salting and sanding of streetS, roofmg operations; prescribed burning, and industrial 

upset conditions. 

6. Traffic and parking reports - In evaluating events or conditions caused, at least in 

part, by mobile sources, a reporting agency will often provide traffic and parking 

reports. Traffic reports usually accompany the documentation for highway 

construction, rerouting of traffic, and infrequent large gatherings. 

7. Ticket sales records - Ticket sales records could be used by a reporting agency to 

determine if the number of people at a gathering could be categorized as an infrequent 

large gathering. 

8. Production schedules and records, inspection reports, and repair orders - These 

-'-' -' ------types-of-records-arrd.eports-may-lYe-use-d-m"lle"SC1ibetlre impact of inc!ustnal'u"p"'s"'eTt --------

condition on air quality data values. This type of upset condition might be caused by 

; ! 

either start-up or shut-down of an industrial process or faulty control equipment. The 

reporting agency must establish the maintenance record and availability of spare parts 

r"r the facility, They must document the actions taken to reduce emissions during the 

L"\'L'n1 

'J Firl' department records - Fire department records can be used to document the time. 

I"c.ltl,'n, anu extent of a structural fire, 

J .. ' ('(lucllrn'nn' and Review Flags 

11iL' ,unllll\sion or supporting documentation is necessary for the EPA (0 evaluate anu 

rl"r,'nd "1'l'r"pnately to Type T data flags. (EPA concurrence on a Type i or V flag is not 

Ill'Cl'''.ln I l'la~ evaluations are carried out hy the appropriate Regional Office (except for 

17 
data flagged for stratospheric ozone intrusion, which are reviewed by the OAQPS), and 

should be completed within 30 days of the supporting docmnentation submittal period: At 

any time during the docmnentation review process, the Regional Office may inform the 

appropriate OAQPS ambient air quality management and monitoring personnel of the 

disposition of the data. 

Type T flags will be reviewed by the Regional Office to ensure that (1) the supporting 

docmnentation adequately defmes the event as not likely to recur; and (2) the supporting 

doJmnentation establishes a causal relationship between the event and the data values. If 

these requirements are met, the RegioDal. Office will attach a concurrence flag to the data set. 

The original Type T flag will remain on the data as well. 

In some instances, EPA. may request additional docmnentation before taking a position 

on the status of a flag. If requested, additional documentation must be submitted by the 

reporting agency within 30 days of the EPA request. The EPA must make a fmal 

detennination of the flagged vaJue(s) within 30 days of the receipt of all needed supporting 

documentation. The Regional Office will then enter the data flag representing their position 

in the AIRS-AQS. 

If the above requirements are not met, the Regional Office will attach a nonconcurrenc~ 

flag to the data. The reporting agency may submit further evidence supporting the flag 

within the next 30 days following the attachment of EPA's nonconcurrence flag. After the 

receipt of additional supponing documentation, the EPA shall make a final detennination of 

the flagged value(s) within 30 days. If it is necessary for the reporting agency and EPA to 

negotiate add it ional time for submitting supponing documentation, the Regional Office should 

con,enatl\ely grant these extensions to facilitate adequate technical review by the reponing 

agL'lk" II I' imp(lnant ((1 state here that it is the intent of this guideline to resolve data 

Ib~~Ul~ l"ue, as timely as possihlc, The Regional Office may change its original 

llPlk,"kllrrCIl,'L' h;I'eu <1n such additional evidence, 

11,111 "'L'IH, 11I1CL' tlwught to he a special event. does recur within the five year period 

,,11,'1 Illl' "Il~ll\.t1II\.'currcncc was recon.lt:d. the Regional Office should reevaluate its position 

,\11 till' "II~IIl,tI "'Ilcurrcnce !lag, At that time, the Regional Office should change its origin"l 

"<'11, IJlll'II,,' t1.l~ l< \ " 11, HICtHlCUrrence !lag to more appropriately reflect the recurring naturc 

18 

, 1 

: ; 

: 

i: 

i i 
of the event. This change is particularly important when the Regional Office is reviewing 

data to be used for policy decisions and for accurately flagging data to be used in later trends 

analyses and standard reports. 

The EPA has reviewed and evaluated several options for accommodating these new 

procedures in the AIRS-AQS. One identified need involves creating a separate AIRS data 

field that would contain a status code indicating EPA's current position on the original data 

flag. As a result, EPA uses the following additional codes in this data field to indicate the 

cutrent status of the initial Type T data flag throughout the documentation review process: 

1. 

2. U.S.EPA Regional Special Event "S" Flagc.a be 

applied when EPA agrees with the reporting agency's flag and request thal 

the data be given special treatment. 

3. U.S.EPA Regional Nonconcurrence "N" Flag--=--lLIl11m:nm:ur:r:ence-code,-to~------­

be applied if EPA does not agree that a request for special data handling is 

justified; or if EPA finds that an applied flag, in the absence of such a 

request for special data handling, is not justified under the specific criteria 

for applying such aflag. 

4. U.S. EPA AIRS-AQS field is blank - indicates that EPA has not responded 

to the reporting agency's request, or that the reporting agency's field 

contains an "r or "V" flag which does not require EPA's response. 

:\ Il<'" chart descrihing the reporting agency's and the Regional Office's data-reporting 

anJ Ib.~~II1~ procetlures is inclutled in Figure 3.2. A summary of the time requirements for 

tilL' 'Uilll1l"I<l11 of n:porting agency "T" nags. supporting documentation, and U.S. EPA 

RC~I<'!1.!1 OtTlcC llaic'S are included :n Tahle 3-1. 

19 
1 . 

Data are collected 

& submitted to AIRS 

by reporting agency 

Do 

NO data appear to be 

r"'IIl---------------<,affected by a special event 

oes the 

ondition affectin 

or special 

ndition? 

YES 

NO Is the 

~ the data YES 

eet the special condition >--.~:=--< event or condition 

. likely to recur? 

, 

def. in Sect. 2.2? 

YES 

Attach a 

Type I flag 

to data. 

Flag Options 

I - infu_ a,aiil,hl" 

\ - \ alidal,·d data 

(hlall'" . no nag 

Does 

documentation show 

event as the culpable 

source? 

Flag Options 

I - info. available 

V - validated data 

(blank) - no nag 

Submit data flag 

to AIRS-AQS & add 

descriptor field 

information, as needed. 

YES Attach a 

Type Tflag 

to data. 

Figurt· .3.1 Process Flow for Selecting & Applying a Data Flag 

20 
, , 

Reporting (Stateilocal) agency 

measures & reports a 

data value (DV) 

DV Reporting 

agency 

Dag 

Re iona! Office Questio~s for reporting agency & o~ers a~ needed Mo~itoring & Air ____ .... to establish recurrence & causa! relatIOnship, 

Programs Contacts for If requested, add' I information must be provided 

pOllutant of interest by reporting agency within 30 days of request. 

As necessary. ,inform HQ of proposed 

disposition & initiate discussion of possible 

im[llications on overall air program, 

Re).'l<lnal Office Joint Coordination Flag 

(t-.ltlfllttlrinp & Air Prop rams Contact,) 

Add Re).'itlnal flag (SIN) within 30 days 

(If ti, 'clllllentation submittal period or 3D 

d,,\', .ilter reLjul'st for add'i information, 

sNFigun' .'.~, Flow Chart for the Dala'Flagging Process 

~I 
i i 

, i 

Reporting agency reports data to EPA via 

AIRS-AQS. 

T flag applied to data value(s) by reporting 

agency. 

Reporting agency submits supporting 

documentation. 

Regional Office evaluates supporting 

documentation. 

As needed, Regional Office requests 

additional information from reporting 

agency. 

Regional Office makes final determination 

to concur or not to concur with T flag. 

If Regional Office does not concur with T 

flag. reporting agency may submit further 

evidence to support their request for special 

event concurrence. 

Regional Office makes change to their 

original decision if warranted by evidence 

presented by reporting agency. 

Ambient air monitoring data collected at 

NAMS/SLAMS must be reported in 90 

days after the end of the calendar quarter 

in which the data were collected. For 

SPMs, data must be reported and certified 

by July 1 of the year following the year 

during which data were collected. 

Must be applied within 30 days after the 

end of the reporting period described 

above. 

Must be submitted within 60 days after the 

submittal for T 

Must be completed within 30 days of the 

supporting documentation submittal period. 

Reporting agency has 30 days to submit 

additional documentation. 

Must be made within 30 days of recc;:iving 

the requested additional information. 

Must be submitted within 30 days of 

EPA's application of a nonconcurrence 

flag. 

Any necessary changes must be made 

within 30 days of the receipt of additional 

evidence. 

Table 3-1. Time Requirements for "T" Flags & 

Supporting Documentation 

22 
Appendix A - Listing of Descriptor Code Options 

The followirig is a listing of descriptions and AIRS codes for events and conditiOns. 

These codes are to be used as part of the documentation required to support special event and 

special condition claims. Note that these are examples of events or conditions that may 

qualify for special treatment or handling but too often do not. They will allow data users to 

sort data by categories, therefore the codes may be used with any flag (Types "I" or "T") 

that . simply indicates the availability of additional information for data values. The codes do 

nof replace the detailed documentation necessary to support the tests and criteria listed in 

Chapter 2. 

HIGH WINDS-SUSPENDEDtRESUSPENDED PARTICULATE MA TfER (PM) - AIRS 

Code A 

Definition: 

High whi.ds combined with high PM levels due to suspension or resuspension of crustal 

material or other particulate matter. The event description should contain information 

demonstrating the presence of an hourly wind speed of greater than what normal peak 

prevailing wind conditions are for the affected area, with no precipitation or only a 

trace of precipitation (observed as scattered drops that do not completely wet or cover 

an exposed area up to a rate of 0.01 inch/hour). 11.12.13 

STRA TOSPHERIC OZONE INTRUSION (03) - AIRS Code B 

Dcfinillon: 

A stratospheric ozone intrusion occurs when a parcel of air originating in the 

,trattlspherc. avcrage height 20 km (12.4 miles),14 is entrained directly to the 

sur!;lCl' tlf the carth. 

Y()I.L\ "(: EHl'JYrIO:O-;S (CO, S02, N02, PM) - AIRS Code C 

IktJllllh'" 

lliv CIIII"I,ln (lr cJCctilln of volcanic materials at the Earth's surface from a crater 

A-I 
SANDBLASTING (PM) - AIRS Code D 

Definition: 

Sandblasting or gritblasting refers to the temporary use of abrasive blasting with 

pressurized air for surface preparation purposes at a given location. 

VEGETATIVE FIRES (CO. PM) - AIRS Code E 

Definition: 

Any frre in which vegetative matter is burned. To the extent possible, the freeform comment field in the descriptor field should include an indication of what 

type of vegetative matter burned (e.g., forest, rangeland, etc.) and of frre type . 

. Fire types may include: 

Wildfire - generally defmed as an uncontrolled fire in vegetation started by nature, 

arson, or accident that requires suppressive action to protect natural resources or values 

associated with natural resources, as well as private property. 

Prescribed· natural fire - a wildfrre for which a conscience decision has been made by a 

land manager to allow the fire to bum in a controlled and restricted manner for a land 

management purpose. 

Prescribed fire - a fire intentionally ignited by a land manager for a land management 

purpose (e.g., ecosystem improvement, hazard reduction, etc.). 

I CLASS I SIZE, ACRES II 

A ,;; 0.25 

B 0.26·9.9 

C 10· 99.9 

D 100 . 299.9 

E 300 . 999.9 

F 1000 ·4999.9 

(; ;, 5000 

I 

A·2 

. , 

; f 

i ; 
This table lists the class and size designations of forest frresl6• Clas~ A and B 

fifes are generally associated with monitoring data collected on a microscale or middle 

scale range from the fife, while Class C and larger fifes would also be expected to 

affect data collected within a neighborhood, urban, regional scale. 

STRUCTURAL FIRES (CO. PM) - AIRS Code F 

Definition: 

Any fife involving some kind of structure, such as a building, residence, industrial 

complex, commercial establishment. 

HIGH POLLEN COUNT (PM) - AIRS Code G 

Definition: 

A pollen count index above 25 grains/cm2 or 1000 grains per cubic meter. 17 The 

pollen count index is usually obtained one of two ways: 1) by use of a coated 

slide mounted on a circular plate that is generally mounted on the top of a seven 

or eightcstory building with an unobstructed air flow, or 2) volumetric method 

(i.e. counting the number of grains per cubic meter.) Other recognized methods 

for measuring pollen levels may be used. 

- .-- - •• ~.~--------~----------------------------------------~----------------------------

CIIDIICAL SPILLS AND INDUSTRIAL ACCIDENTS (CO, S02, N02, PM) -

AIRS Code H 

Dd'inition: 

El11i~sions that result from accidents such as fire, explosions, power outages, train 

lkrailll1ent~. vehicular accidents. or combinations of these. 

]]{\FFI(.!'.·\TTER:,\S (CO) - AIRS Code I 

I klll1lll"11 

.\ "'l1dlll<'l1 re,ulttn~ from a major accident (rather than frequent minor accidents) 

,'I ,1",1'1 Jur;lIlon Ohqruclilln. such as demolition or construction. During these 

,''!IJIII<'II' Iile ILld 01 traffic I11<JY increase until it exceeds the maximum capacity 

A-3 
of a given street or highway. Speeds are reduced substantially and stopp;lges may .. occur for short or long periods of time because of downstream congestion. 

CONSTRUCTIONffiEMOLITION (PM) - AIRS Code J 

Definition: 

The building/destroying/renovation of any residential, institutional, commercial or 

industrial building, structure, facility, or installation. 

AGRICULTURAL TILLING (PM) - AIRS Code K' 

Definition: 

The act of preparing dry soil for cultivation or for controlling the growth of weeds 

by the use of mechanical devices during periods with an hourly average wind 

speed greater than what is expected for that area. 

HIGHWAY CONSTRtJCTION (PM) - AIRS Code L 

Definition: 

The act of building anew, or repairing an existing, highway, road, or street. 

REROUTING OF TRAFFIC (CO) - AIRS Code M 

Definitilln: 

A temporary deviation or detour of vehicular traffic because of an accident, 

construction. or demolition. 

llelll11111111 

III,' ,ll'l'liCalion Ill' salt and/or sand to the road surface to increase traction and/or 

I"c'\ ,'Ill Ihe ,urLIL'l' water from refreezing after it has melted. 

A-4 

. ! 

! : 

, : 

, 

, , 

I t 

, 1 
INFREOUENT LARGE GATHERINGS (CO, PM> • AIRS Code 0 

Definition: 

A gathering of more than 10,000 people (5000 cars) at anyone time and at a 

single location. Unusual traffic congestion may be associated with the event. 

ROOFING OPERATIONS (PM, S02)· AIRS Code P 

Definition: 

The process of building, repairing, or recoating the external upper covering of a 

house or building that involves the application of a petroleum-based material 

(usually heavy residuals from a refining operation) to a roof. The material is 

heated and then sprayed or rolled onto the surface. 

CLEANUP AFTER A MAJOR DISASTER (CO, PM, S02) • AIRS Code R 

Definition: 

For the purposes of flagging, major disasters are serious public misfortunes for 

which State or Federal relief has been granted. 

INDUSTRIAL PLANT START-UPS, SHUT-DOWNS, PROCESS UPSETS, OR 

Ggll':r.ROr, EQlJIJ!MEN+ MALImNC+IQNS (Q3, N02, J!M, CO, S02, J!B)-AIRS 

Code S 

Definition: 

Emissions that result from plant start-ups, shut-downs, process upsets. or control 

~quipmcnt malfunction or combinations of these events. 

[VJJ~R':\TlO'AL POLLUTANT TRANSPORT (PM) - AIRS Code T 

Ikllll1ll{l1l 

'1 r:tll'p"n of a paniculate matter over international horders." The original source 

<II lill' pollution may he anthropogenic or nonanthropogcnic. This code, if used in 

,<lIlIUIl(11<1I1 with a reponing agency's type "I" nag. may he used to document 

ll'dJrrlll~ ,pcci;d conditions in suppon of a PM·IO waiver application. 

A·5 
OTHER TYPES OF EVENTS (03. CO. PM. S02. N02. pm - AIRS Code U 

The aforementioned list of types of events is based on the EPA's previous experiences 

with the circumstances surrounding special events. There may be truly discrete and rare 

events that are not likely to recur that are not listed within this appendix. For these other 

cases, the reporting agency should use the "Other types of events" code. This code indicates 

that, although an event may qualify for a Type T flag, it is not adequately described by one . 

of the descriptor categories. (As appropriate, EPA will include new descriptor codes for 

special events into the AIRS-AQS flagging options.) 

OTHER TYPES OF CONDmONS (03. CO. PM. S02. N02. PB) - AIRS Code W 

A reporting agency may use this code for two purposes. The first is to document a 

special condition that is not accurately described by any other descriptor code in this 

Appendix. For PM-IO special conditions, this type of documentation may be used to support 

a waiver application. The second use is to provide general information on a data value(s) 

that may be of interest to others who are using the data: This second case does not imply 

that the data will be treated as a special condition, it only serves to inform others of the 

circumstances surrounding a data value(s). 

A-6 

{ , 

i , 

! I 

, , , , 

, 1 

: i 
Appendix B - Listing of Events Not Eligible 

For Approval as Special Events 

The following information is provided as a list of example events which would not 

generally be considered as special events as defmed in Section 2.2 of this document.. This 

list is not exhaustive. Reporting agencies may wish to docmnent these types of events by 

a~ching an "J" flag to the data value(s) and providing supplementary information in the 

appropriate descriptor fields in A1RS-AQS. 

A. Implementing Transportation Controls 

Transportation contrormeasures are not considered special, and the data collected 

during implementation of transportation controls should not be flagged for special treatment. 

If, however, traffic must be temporarily rerouted during the implementation of the 

transportation control measures or some congestion occurs due to initial start-up of the 

transportation plan, . the data collected at monitors near the rerouted traffic or congestion may 

be flagged for special treatment. 

I1 Stagnation/Inversions 

~------~S(agnation-and-inversions-are-frequent-climatologi"cal-occurrellCt:sthatllliIsCo"'e--------­

considered in evaluating whether a control program is adequate to attain and maintain the 

I"AAQS. An inversion is·said to occur at a point, or through a layer, where temperature 

increases with increasing height. Surface-based inversions are those that extend vertically 

fr(llll the surface to some altitude aloft. Inversions occur very frequently, are usually shortII\~J. ~lnJ disperse shortly after sunrise.'9 Because inversions are expected to occur 

'le'llue'lll h and arc part of normal weather patterns, they are not considered special events for 

Ihl' rurr'''"' (It tla)!)!ing data, 

\1."'11.111<111 cpis(I<..\es arc periods of more than I day with surface wind speeds of 

,l'lIl'"i1l l -1 ITll'IL'rs'second or less and no precipitation or frontal passage, In some parts of 

Ih,' { IIlIl'd SI,lll", sta)!nali(\n usually persist for an extended period of time, and they can 

B-1 
affect an entire ai~ basin; therefore, they are not generally considered for special 

treatment. 20,21 

C, High-Sulfur Oil Refining 

High-sulfur oil refining refers to the process of refining crude oil with a sulfur content 

that is 20 percent or greater than the design capacity of the refining operation, Because this 

is ~common practice at many refmeries, it is not considered to be a special event for the , 

purpose of data flagging, 

D, Sootblowing from Ships 

Sootblowing from ships is a method in which air is used to remove deposits that may 

build up on the walls of the vessel's boiler tubes, This is a common practice that is either· 

controlled or limited (in many areas of the country) by establishing opacity limits. Because 

these activities are common, sootblowing from ships (like general sootblowing from utility 

and industrial boilers) is not considered a special event and data affected by this activity 

would not receive special treatment. 

E. Noncompliance--Local Sources 

Limited noncompliance of local sources can be expected occasionally as a result of 

rr"ces~ upsets or malfunctioning control equipment. These events are usually classified as 

"ursets" or "malfunctions" as defined by the applicable State or lotal agency regulations, or 

thL" 1l1;IY he considered a violation of applicable emission or opacity limits. If these events 

arc e;lu,,:d hy upsets or malfunctions, they should be so noted and reported to the appropriate 

("Ill r, 'I a~ency. I f they constitute a violation. the appropriate legal remedies will be taken. 

II k~,t1 aClllln is taken. the air quality data collected in the vicinity of the source will in all 

Ilkllil,,,,,1 be u,ed in the legal proceedings. and any appropriate limitations associated with 

Ilk· ,1.11.1 \\"l11J he reviewed and evaluated as part of the legal process. Becausedata 

,.'lkdL·c\ Jl1r1!1~ nllncomrliance conditions have special uses and the source is required to 

n"IIIL lilL· SI,lte tit the upset or malfunction. noncompliance of local sources is not considered 

B-2 

i ~. 

I ; 

, I 
F. Unusual Lack of Precipitation 

Lack of precipitation alone would not be considered as a special event because ·if has 

very little impact on ambient air pollutant levels. Lack of precipitation or drought conditions 

combined with high winds, however, could be considered as a special event and documented 

with the descriptor code for high wind suspended/resuspended particulate matter. 

G. Data not Meeting Applicable Ouality Assurance/Quality Control Requirements of the 

EPA/State/Local Agency 

Occasionally, it may be necessary to invalidate ambient air monitoring data on the basis 

of not meeting appropriate quality assurance/quality control requirements or because of a 

monitor malfunction. This action is not considered as a special event or a special condition. 

A more appropriate way to treat this type of data is to use null value data codes, as defined 

in the AlRS-AQS system, to indicate that invalid data have been deleted and to provide an 

indication of the nature of the problem, for example poor quality assurance results or general 

power failure. 

B-3 
Appendix C ~ Listing of Acronyms 

I. AIRS - Aerometric Infonnation Retrieval System 

2. AQS - Air Quality Subsystem (of the Aerometric Infonnation Retrieval System) 

3. CFR - Code of Federal Regulations 

4. CO - Carbon Monoxide 

5. FR - Federal Register 

6. NAAQS - National Ambient Air Quality Standards 

7. NADB - National Air Data Bank 

8. NAMS - National Air Monitoring Stations 

9. N02 - Nitrogen Dioxide 

10. 03 - Ozone 

II. OAQPS - Office of Air Quality Planning and Standards 

12. PB - Lead 

13. PM-IO or PM - Particulate Matter with aerodynamic diameter less than or equal to a 

nominal 10 micrometers 

14. SIP - State Implementation Plan 

15. SLA!\IS -StatefLocal Air Monitoring Stations 

I () S02 - Sulfur Dioxide 

17 SI'\I~ - Special Purpose Monitors (e.g. special study. industrial, federal non-EPA) 

IS TSP· Tntal SusPended Particulate 

1'1 l .S.F1',,\ or EPA - lJniled Stales Enl'ironmental Protection Agency 

C-I 
REFERENCES 

1. Guideline on the Identification ,and Use of Air Ouali1y Data Affected by Exceptional 

Events, Upited States Environmental Protection Agency, Office of Air Quality Planning 

and Standard~, Research Triangle Park, NC, EPA450/4-86-007, July1986. 

2. Guideline for the Interpretation of Air Ouality Standards, United'States Environmental 

Protection Agency, Office of Air Quality Planning and Standards, Research Triangle 

Park, NC, OAQPS No. 1.2-008 (revised February 1977). 

3.; United States Code of Federal Regulations, Title 40, Part 51, Section 51.110(1), July 

1993. 

4. United States Code of Federal Regulations, Title 40, Part 50, Section 50.6, July 1993. 

5. Aerometric Information Retrieval System (AIRS), Air Quality Subsystem (AQS), 

United States Environmental Protection Agency, Research Triangle Park, NC. 

6. Clean Air Act, as amended in 1990, PL 101-549, November 15, 1990. 

7. Federal Register, Title 40, Part 51 fmal rule ·State Implementation Plan Requirements 

for Serious PM-I0 Nonattainment Areas", Volume 59, Number 157, August 16, 1994, 

pp.41998-42017. 

8, United States Code of Federal Regulations, Title 40, Part 58, Appendix D, July 1993. 

9, Guideline on Air Quality Models (Revised), United States Environmental Protection 

----' ______ A!!cnq~._Office-oLAir-Quality-f!lanning_and--Standllrds,Researeh-'Friangle-Park;-NC~, -----

EPA-45012-78-027R. (NITS PB 86-245-248), July 1986, and subsequent revisions. 

I () h:deral Register. Title 40, Part 58 final rule "Ambient Air Quality Surveillance 

l{q~ulations". Volume 59, Number 155, August 12, 1994, pp. 41626-41629. 

II I<cccptllr Modt.:! Technical Series. Volume I, Overview of Receptor Model Application 

I,' 1'.1I1lculate Sourct: Apportionment. United States Environmental Protection Agency, 

(III icC III Air Quality Planning and Standards. Research Triangle Park, NC. EPA4'11 -l SI(lI(13. July 1981. 

I: 1\,', l'I'I' 'f \1. ",kl Technical Series. Volume II, Chemical Mass Balance, United States 

I """"Ilfllclllal I'r(lleclion Agency. Office of Air Quality Planning and Standards. 

1~'c""",!J1 nan~k Park. NC. EPA-450/4-81-016h. July 1981. 

I; I~,,"i'l'" \1.'<.kllcclllllcal Series. Volume III. User's Manual for Chemical Mass 

I\., ;,,',., \ 1. ',kl, I' (lIll'l1 Stales Environmcntal Prolection Agency, Office of Air Quality 

1'.,,,,,,:1,: .II\J '\1.lno:lrO\. Rescarch Triangle Park. NC. EI'A-450/4-90-004. January 
14. Mohnen, V.A., and E.R. Reiter. International Conference on Oxidants, 1976 -

Analysis of Evidence and Viewpoints Part m. The Issue of Stratospheric Ozone 

Intrusion. United States Environmental Protection Agency, Research Triangle' Park, 

Ne, EPN600/3-77/115, 1977. 

15. Bates, R.L. and J.A. Jackson. Glossary of Geology. Second Edition: American 

Geological Institute, Falls Church, VA, 1980 ... ' 

16. Personal Communication with Doug Francis of the United States Department of 

Agriculture (USDA) Forest Service, National Forests of North Carolina, Asheville, 

North Carolina, June 1994. 

17. Air Pollution Aspects of Aeroallergens (Pollens), National Air Pollution Control 

Administration Consumer Protection and Environmental Health Services, Department of 

Health, Education, and Welfare, September 1969. 

18. PM-tO State Implementation Plan Development Guideline, United States Environmental 

Protection Agency, Research Triangle Park, NC, EPA450/2-88-001, June 1987. 

19. Barry, R.G., and R. J. Chorley. Atmosphere. Weather, and Climate, 6th edition, 

Routledge, New York, NY, 1987. 

20. DeMarrais, G .A. Air Pollution Concentrations Associated with Stagnation and 

Restricted Visibility, Eastern North America, August 1976, United States 

Environmental Protection Agency, Environmental Sciences Research Laboratory, 

Research Triangle Park, NC, 1980. 

21. Briggs, G.A. Stagnation Diffusion Observed in a Deeply Pooling Valley During 

ST AGMAP, National Oceanic and Atmospheric Administration, Research Triangle 

Park, NC, United States Environmental Protection Agency, Atmospheric Research and 

Exposure Assessment Laboratory, Research Triangle Park, NC, EPA/600/A-92/233, 

1992. 

! ! 

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, TECHNICAL REPORT DATA 

(Please read Inslruclior.:; an revcrse before complcting) 

I. REPORT NO. 2. 3. RECIPI~T'S ACCESSION NO. 

EPA-454/D-94-001 

•. TITLE AND SUBTITLE S. REPORT DATE 

Guideline on the Identification and Handling of Ambient Air September 1994 (draft document) 

Quality Data Affected by Special Events or Special Conditions 6. PERFORMING ORGANIZATION CODE 

7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO. 

Lee Ann B. Byrd, Breda Phillips 

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT NO • 

. . U.S. Environmental Protection Agency 

Office of Air Quality Plannillg and Standards 

Technical Support Division (MD-14) & Air Quality II. CONTRACf/GRANf NO. 

Management Division (MD-15) 

Research Triangle Park, NC 27711 

12. SPONSORlNG AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED 

Director Draft report as of September 8, 

Office of Air Quality Planning and Standards 1994 

Office of Air and Radiation 14. SPONSORlNG AGENCY CODE 

U.S. Environmental Protection Agency EPAI200/04 

Research Triangle Park, NC 27711 

15. SUPPLEMENT AR Y NOTES 

Supersedes uGuideline on the Identification and Use of Air Quality Data Affected by Exceptional 

Events". EPA-450/4-86-007, July 1986. 

16. ABSTRA( °T 

This document provides guidance on the procedures for flagging and reporting data associated with 

various circumstances including data validation, the submittal of information related to data, and/or the 

requestin~ for special treatment of data accompanied by supporting documentation related to a special 

event or speCial condition. 

17 KEY WORDS AND DOCUMENT ANALYSIS 

• PI \("HII'10RS b IDENTIFIERS/OPEN ENDED TERMS c. COSATI Flcld!Gruup 

Amniolll .11' lLtl.t 11.1~~ lilt' Air Pollution Control 

Amniolll .11' J.Il.! ,,!\ IJa[[(l1l Ambient Air Monitoring Data 

ExcepI111ll,d L'\ enl ... Air Quality Mana~ement 

SpeCIal II ,'nl' 

SpeCial (""TlJill"'" 

It< IlI"':!-: I ... ,,', ',. I ~ SHTRITY CLASS 1fIt'/,orrl 21 NO {)I' PACii:S 

Unclassified 37 

Rek",c ! lillllllleJ ~fI SECTRfTY CLASS (Pug" 22 PRICE 

Unclassified 

1-:1':\ h"l11 ___ (I 1 ,k., ,.~ . , . ,., ., . . ,', ,""h.~1)1.I,1!