UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION 4

Sam Nunn Atlanta Federal Center

61 Forsyth Street SW

Atlanta, Georgia 30303-8960

DATE:	October 6, 2009

SUBJECT:	Technical Support Document for Notice of Proposed Rulemaking
– Determination of Attaining Data for the 1997 Fine Particulate Matter
Standard

FROM:	Joel Huey, Environmental Scientist /s/

Regulatory Development Section 

TO:		File

THRU:	Lynorae Benjamin /s/

		Chief, Regulatory Development Section

A.  BACKGROUND

On July 18, 1997 (62 FR 36852), EPA established health-based PM2.5
National Ambient Air Quality Standards (NAAQS) as 15.0 micrograms per
cubic meter (µg/m3) based on a 3-year average of annual mean PM2.5
concentrations, and 65 µg/m3 based on a 3-year average of the 98th
percentile of 24-hour concentrations.  EPA established the standards
based on significant evidence and numerous health studies demonstrating
that serious health effects are associated with exposures to particulate
matter.  The process for designating areas following promulgation of a
new or revised NAAQS is contained in section 107(d)(1) of the Clean Air
Act.

EPA and State air quality agencies initiated monitoring for the 1997
PM2.5 NAAQS in 1999.  On January 5, 2005 (70 FR 944), EPA published its
air quality designations and classifications for the 1997 PM2.5 NAAQS
based upon air quality monitoring data from those monitors for calendar
years 2001-2003.  These designations became effective on April 5, 2005. 
The Hickory-Morganton-Lenoir, North Carolina, area (hereafter referred
to as “Hickory, North Carolina”) and the Greensboro-Winston
Salem-High Point, North Carolina, area (hereafter referred to as
“Greensboro, North Carolina”) were designated nonattainment for the
1997 PM2.5 NAAQS (see 40 CFR part 81).  This Technical Support Document
(TSD) summarizes the 2006-2008 data EPA is using to support its
determination that the Hickory and Greensboro areas now have attaining
data.

B.  EPA REQUIREMENTS

A nonattainment area for the 1997 PM2.5 NAAQS is determined to have
attaining data when the design values for the annual and the 24-hour
standards meet the requirements stipulated in 40 CFR Part 50, section
50.7 as follows:

  

(1) The annual primary and secondary PM2.5 standards are met when the
annual arithmetic mean concentration, as determined in accordance with
40 CFR Part 50, Appendix N, is less than or equal to 15.0 µg/m3; 

(2) The 24-hour primary and secondary PM2.5 standards are met when the
98th percentile 24-hour concentration, as determined in accordance with
40 CFR Part 50, Appendix N, is less than or equal to 65 µg/m3.

	

Upon determination by EPA that an area designated nonattainment for the
PM2.5 NAAQS has attained the standard, 40 CFR section 51.1004(c)
provides that the requirement for such area to submit attainment
demonstrations and associated reasonably available control measures,
reasonable further progress plans, contingency measures, and other
planning SIPs related to attainment of the PM2.5 NAAQS shall be
suspended until the area is redesignated to attainment, at which time
the requirement no longer applies.  However, if EPA subsequently
determines that the area has violated the PM2.5 NAAQS, the requirement
to submit such plans is reinstated.

C.  EPA’S ANALYSIS OF MONITORED DATA

1.  2006-2008 data

EPA’s determination that the Hickory and Greensboro nonattainment
areas have attaining data is based upon quality assured, quality
controlled and certified ambient air monitoring data for the 2006-2008
period, as measured by Federal reference method, Federal equivalent
method, or Approved Regional Method monitors described in 40 CFR Part
50, Appendix N.  The monitors and data used to determine the design
values for the Hickory and Greensboro nonattainment areas are indicated
in Tables 1-4 below.

Table 1.  Design Value for Counties in the Hickory, North Carolina,
Nonattainment Area for 1997 PM2.5 NAAQS – Annual Standard

Location	AQS site ID	2006

Average	2007

Average	2008

Average	2006-2008

Design Value

Catawba County	37-035-0004	15.163	14.592	12.806	14.2



Table 2.  Design Value for Counties in the Hickory, North Carolina,
Nonattainment Area for 1997 PM2.5 NAAQS – 24-Hour Standard

Location	AQS site ID	2006

98th

Percentile	2007

98th

Percentile	2008

98th

Percentile	2006-2008

Design Value

Catawba County	37-035-0004	32.9	30.7	 25.2 	30



Table 3.  Design Value for Counties in the Greensboro, North Carolina,
Nonattainment Area for 1997 PM2.5 NAAQS – Annual Standard

Location	AQS site ID	2006

Average	2007

Average	2008

Average	2006-2008

Design Value

Davidson County

Guilford County	37-057-0002

37-081-0013	15.126

14.497	14.636

13.140	13.611

11.577	14.5

13.1



Table 4.  Design Value for Counties in the Greensboro, North Carolina,
Nonattainment Area for 1997 PM2.5 NAAQS – 24-Hour Standard

Location	AQS site ID	2006

98th

Percentile	2007

98th

Percentile	2008

98th

Percentile	2006-2008

Design Value

Davidson County

Guilford County	37-057-0002

37-081-0013	31.0

31.3	30.9

28.4	24.7

24.6	29

28



2.  2009 data 

	EPA does not yet have State certified air quality data for the 2009
calendar year.  The State certified air quality data for the entire 2009
calendar year will not be available until well into calendar year 2010
and, therefore, cannot be used for purposes of design value calculations
during calendar year 2009.  EPA did not rely upon any 2009 data to
support its proposed determination that the above areas have attaining
data.  However, as part of the proposed determination, EPA notes that a
portion of the 2009 air quality data is currently available.  This
partial 2009 data indicates a continuing trend consistent with EPA’s
proposed determination:  the air quality monitors located in the Hickory
and Greensboro areas continue to show attaining data for the 1997 PM2.5
NAAQS.  The portion of the 2009 data that was available when EPA’s
proposed determination was published is provided below. 

Table 5.  2009 Data for the Hickory, North Carolina, Nonattainment Area

Location	AQS site ID	First Quarter 2009	Second Quarter 2009

Catawba County	37-035-0004	11.24482759	Not available



Table 6.  2009 Data for the Greensboro, North Carolina, Nonattainment
Area

Location	AQS site ID	First Quarter 2009	Second Quarter 2009

Davidson County

Guilford County	37-057-0002

37-081-0013	11.39333333

9.45862069	9.657142857

8.843181818



D.  CONCLUSIONS AND RECOMMENDED AGENCY ACTION

	The available quality assured, quality controlled, and certified
ambient air monitoring data for 2006-2008 shows that the Hickory and
Greensboro PM2.5 nonattainment areas have monitored attainment for the
1997 PM2.5 NAAQS.  It is therefore recommended that the Hickory and
Greensboro areas be determined to have attaining data for the 1997 PM2.5
NAAQS.

Although the available 2009 data is not relied upon for this
determination, it shows an apparent continuing trend of attaining data
for these areas and is provided in this TSD for informational purposes
only. 

 Design values are the metrics that are compared to the NAAQS levels to
determine attainment, and are calculated as follows:

(1) The 3-year average of annual means for a single monitoring site or a
group of monitoring sites (referred to as the “annual standard design
value”).  If spatial averaging has been approved by EPA for a group of
sites which meet the criteria specified in section 2(b) of this appendix
and section 4.7.5 of appendix D of 40 CFR part 58, then 3 years of
spatially averaged annual means will be averaged to derive the annual
standard design value for that group of sites (further referred to as
the “spatially averaged annual standard design value ”). Otherwise,
the annual standard design value will represent the 3-year average of
annual means for a single site (further referred to as the “single
site annual standard design value ”).

(2) The 3-year average of annual 98th percentile 24-hour average values
recorded at each monitoring site (referred to as the “24-hour standard
design value”).  (See 40 CFR part 50 Appendix N.)

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