1 

December 2010 Addendum to EPA’s May 5, 2010 Technical Support Document 

Pinal County, Arizona Area Designation for the 

2006 24-hour Fine Particle National Ambient Air Quality Standards 

The table below identifies the portion of Pinal County in Arizona that EPA has designated as not 

attaining the 2006 24-hour fine particle (PM2.5) national ambient air quality standard (NAAQS). 

A county (or part thereof) is designated as nonattainment if it has an air quality monitor that is 

violating the standard or if the county or portion of the county is determined to be contributing to 

the violation of the standard in a nearby area. 

Area Arizona Recommended 

Nonattainment Area within 

Pinal County 

EPA’s Final Designated 

Nonattainment Area within Pinal County

Pinal T4S, R3E – R4E 

T5S, R3E – R4E (excluding 

sections 12, 13, 24, and 25) 

T4S, R2E – R4E, except Indian Country; 

T5S, R2E – R4E, except Indian Country; 

T6S, R2E – R4E; 

T7S, R2E, except sections 13 - 36; 

T7S, R3E, except- 

• NW 1⁄4 , NW 1⁄4 of section 15, SW 1⁄4 , NW 1⁄4 

of section 15, NW 1⁄4 , SW 1⁄4 of section 15, 

SW 1⁄4 , SW 1⁄4 of section 15; 

• sections 16 – 21; 

• NW 1⁄4 , NW 1⁄4 of section 22, SW 1⁄4 , NW 1⁄4 

of section 22, NW 1⁄4 , SW 1⁄4 of section 22, 

SW 1⁄4 , SW 1⁄4 of section 22; 

• NW 1⁄4 , NW 1⁄4 of section 27, SW 1⁄4 , NW 1⁄4 

of section 27, NW 1⁄4 , SW 1⁄4 of section 27, 

SW 1⁄4 , SW 1⁄4 of section 27; 

• sections 28-33; and 

• NW 1⁄4 , NW 1⁄4 of section 34, SW 1⁄4 , NW 1⁄4 

of section 34, NW 1⁄4 , SW 1⁄4 of section 34, 

SW 1⁄4 , SW 1⁄4 of section 34; 

T7S, R4E 

EPA has designated the remainder of state lands within Pinal County, Cochise, Gila, Graham, La 

Paz, Maricopa, Pima, Yavapai, and Yuma counties, and, except as noted below, Indian country 

located within those counties, as “unclassifiable/attainment.” EPA is deferring designation of the 

Gila River Indian Community reservation which is located in Pinal and Maricopa counties, and 

Ak-Chin Indian Community reservation, which is located in this portion of Pinal County. 

See Figure 1-A.
2 

Figure 1-A: Areas Newly Designated for the 2006 24-Hour PM2.5 NAAQS 

U n i t e d S t a t e s U n i t e d M S t a t e s e x i c o M e x i c o

West Central PinalPM2.5 Nonattainment Area - FINAL

Pima County

Maricopa County

Yavapai County

Pinal County

Gila County

Yuma County

Coch

La Paz County

Graham Co

Santa Cruz County

0 

12

AIR1000054_9 28 October 2010

Sources: EPA (2010), ESRI (2010),TANA (2006).

Final EPA PM-2.5 Deferred Tribal LaDesignated PM-2.

Previously DeferreDesignated "Uncla

Proposed EPA PM
3 

Background

In October of 2009, EPA notified the Governor of Arizona and Tribal leaders of tribes with lands 

located in Pinal and Maricopa counties that a monitor in Pinal County (i.e., the “Cowtown” 

monitor) was violating the 2006 24-hour PM2.5 standard based on the most recent (2006-2008) 

air quality monitoring data. Due to this newly monitored violation, and due to the need for 

additional time to collect data and evaluate the area to determine an appropriate nonattainment 

area boundary for the area, EPA decided to defer the area designation of Pinal County, Maricopa 

County (i.e., the other county comprising the Phoenix-Mesa-Scottsdale CBSA), and the seven 

nearby counties (i.e., Cochise, Gila, Graham, La Paz, Pima, Yavapai, and Yuma counties) 

surrounding the Phoenix-Mesa-Scottsdale CBSA,1 for the 2006 24-hour PM2.5 standard and 

potentially contributing to the violations of the NAAQS in Pinal County.2 See Figure 1 of EPA’s 

May 5, 2010 Technical Support Document (TSD). 

On May 10, 2010, EPA notified the Governor of Arizona of its intent to designate a portion of 

Pinal County nonattainment for the 2006 24-hour PM2.5 NAAQS thereby modifying the 

recommendation for an attainment designation for Pinal previously made by Arizona. In its TSD, 

EPA explained that emission inventory data, combined with speciation and source apportionment 

data, point to agricultural activities and cattle feedlots, as well as other nearby sources of PM2.5, 

as primary sources contributing to PM2.5 levels at the Cowtown monitor on days with 

exceedances of the 24-hour PM2.5 NAAQS. In addition, EPA assessed air quality and 

meteorological data, including data on monthly exceedances of the 24-hour PM2.5 standards; 

wind direction and speed for hourly and daily PM2.5 levels; correlation of PM2.5 with PM10 at the 

Cowtown monitoring site; and the diurnal pattern of PM10, wind speed, and temperature for 

PM2.5 exceedance days. Results of these assessments led EPA to conclude that agricultural lands 

and cattle feedlots, and activities associated with these operations, particularly those to the south 

and southwest of the monitor, contributed to PM2.5 levels at the monitoring site. By contrast, 

EPA concluded that the emissions sources in surrounding counties and eastern Pinal County are 

not contributing to the violations of the 2006 24-hour PM2.5 standard measured at the Cowtown 

monitor. Therefore, EPA proposed to designate the central-western portion of Pinal County, 

Arizona, as “nonattainment” for the 24-hour PM2.5 NAAQS as shown in Figure 2 of EPA’s 

(TSD). 

In a letter dated July 19, 2010, the Governor of Arizona responded to EPA’s May 10, 2010 

notification of its intention to modify the state’s initial designation recommendation. The 

Governor argued that a nonattainment designation was unwarranted, given the evidence that 

exceedances of the PM2.5 NAAQS are an artifact of the high concentrations of PM10, and given 

the progress Arizona is making in reducing PM10 concentrations. EPA notes that these 

arguments did not address the fact that there are monitored violations of the 2006 24-hour PM2.5

NAAQS in the area, nor negate EPA’s obligation under section 107(d) to designate as 

 

1

 As described in EPA’s final rule promulgating initial PM2.5 designations for the 2006 24-hour standard, in 

evaluating areas potentially contributing to a monitored violation, EPA examined those counties located in the 

surrounding metropolitan statistical area (in this case, Pinal and Maricopa counties), and those nearby counties one 

or two adjacent rings beyond. See “Air Quality Designations for the 2006 24-hour Fine Particle (PM2.5) National 

Ambient Air Quality Standards,” 74 FR 58688, November 13, 2009, page 58694. 

2

 Unless otherwise specified, references to “counties” or to “Arizona” include all lands within the geographic 

boundary and do not differentiate between lands under state or tribal jurisdiction. 
4 

nonattainment those areas that are violating the NAAQS, or contributing to nearby areas that are 

violating the NAAQS. 

Anticipating that EPA would move forward with the nonattainment designation for the Pinal 

area, the Governor also offered a “counter-proposal” to EPA’s recommended nonattainment area 

boundary, which is significantly smaller than the boundary EPA originally proposed in its TSD. 

See Figure 2-A. In support of the Governor’s recommended alternative boundary, the Arizona 

Department of Environmental Quality (ADEQ) submitted a technical report entitled “Arizona 

Air Quality Designations, Technical Support Document, Boundary Recommendation for the 

Pinal County 24-hour Standard PM2.5 Nonattainment Area (July 13, 2010),” herein referred to as 

ADEQ’s “technical report.” 
5 

Figure 2-A. Arizona’s Recommended PM2.5 Nonattainment Area Boundary 
6 

EPA has reviewed the Governor’s July 19, 2010 letter and ADEQ’s technical report, and as a 

result has made a revision to the southwestern portion of the originally proposed nonattainment 

boundary. We have determined that the Table Top Wilderness Area, which occupies most of the 

southwestern corner of our proposed nonattainment area, along with state lands to the south of 

the wilderness area, are not likely to be contributing to the exceedances measured at the 

Cowtown monitor due to the absence of sources of emissions of PM2.5 or PM2.5 precursors in the 

wilderness area. As illustrated by Figure 3-A (page 12 below) very few sources of PM2.5 

emissions are present in this area and future development will be limited by virtue of the 

restrictions that apply to wilderness areas. Given these considerations, we are revising our 

proposed boundary for the nonattainment area to exclude the Table Top Wilderness Area and 

state lands to the south of the final nonattainment area. See Figure 4-A on page 13 of this 

Addendum. 

A summary of the main points in ADEQ’s technical report and EPA’s analysis of these issues 

follows. 

Emissions Data 

ADEQ’s July 13, 2010 technical report considered the Pinal County source apportionment study 

conducted by the Pinal County Air Quality Control District (PCAQCD) in 2003 and provided 

two back trajectories to analyze emissions transport to the Cowtown monitor. ADEQ’s technical 

report states that the modeled days show winds from the south-southwest, likely carrying 

particulate matter from feedlots, agricultural fields, and unpaved roads.3 Based on their analysis 

of PM2.5 versus PM10 concentrations as presented in the July 13, 2010 document, ADEQ 

concludes that the concentrations seen at Cowtown are attributable to nearby feedlots and 

agricultural activities.4 In support of a smaller designated nonattainment area, ADEQ states that 

the other PM2.5 monitors in Arizona (Casa Grande, Apache Junction, Douglas, and others shown 

in Figure 4 of EPA’s TSD) record considerably lower concentrations and do not show 

exceedances that correlate with Cowtown. ADEQ concludes that this demonstrates that the 

emissions do not travel far and are from very localized sources.5

 

EPA agrees with ADEQ’s conclusion that the PM2.5 concentrations monitored at Cowtown are 

strongly influenced by local sources. However, with regard to the extent of the nonattainment 

area, EPA notes that CAA section 107(d)(1)(A) defines a nonattainment area as one that does not 

meet, or that “contributes to” ambient air quality in a nearby area that does not meet the 

NAAQS. The mere absence of violating monitors in other locations does not establish that 

sources in those locations are not contributing to nearby violations. The pollution rose in our 

TSD (Figure 11) indicates that most PM2.5 exceedances in this area occur when resultant wind is 

from the southwest to southeast. Figure 3 in our TSD and Figure 5-A below show that emission 

sources of concern (e.g., feedlots and geologic soil sources such as agriculture and unpaved 

roads) are located in areas to the southwest and southeast of ADEQ’s recommended 

nonattainment area. Thus, the emissions inventory data and related maps do not support 

 

3

 July 13, 2010 ADEQ TSD, p 13. 

4

 Ibid, p 17 

5

 Ibid p 14. 
7 

Arizona’s recommended boundaries, but rather argue for a larger nonattainment area including 

the portion of the south-southwestern half of the county that contains emissions sources (e.g., 

feedlots and agriculture) similar to those included within ADEQ’s proposed boundary. 

EPA’s final boundary includes areas for which emissions data show a relatively high prevalence 

of the types of sources (e.g., feedlots and agriculture and unpaved roads (geological soil)) 

contributing the most to the PM2.5 emissions at Cowtown. See Figure 5-A. 

 

Air Quality Data 

Both Arizona’s recommended nonattainment area and EPA’s proposed nonattainment area 

encompass the location of the violating monitor. However, section 107(d)(1)(A) of the CAA 

requires that areas that are contributing to violations in a nearby area must also be included 

within a nonatttainment area. While feedlot soil makes up a large portion of the PM2.5 mass 

measured at the Cowtown monitor, geologic soil also contributes to high concentrations of 

PM2.5. EPA believes that Arizona’s recommended boundary excludes similar feedlot and 

geologic soil sources that are contributing to violations at the Cowtown monitor. To ensure that 

contributing sources are included in the nonattainment area, EPA has finalized a nonattainment 

area boundary that extends farther to the south and west of Arizona’s recommended boundary. 

See Figure 5-A. By inclusion of these sources within the boundaries of the nonattainment area, 

Arizona will be evaluating these sources for potential controls in its attainment plan in order to 

provide for expeditious attainment of the NAAQS in this area. 

Population Density and Degree of Urbanization 

EPA evaluates population data because it can give an indication of whether it is likely that 

population-based emissions in an area are contributing to PM2.5 levels at the violating monitor. 

In addressing this factor, ADEQ’s technical report notes that 95 percent of the Pinal County 

population lives along the Interstate-8 and Interstate-10 corridors (page 19). These corridors lie 

to the south and east of Arizona’s recommended nonattainment area. The executive summary of 

ADEQ’s technical report asserts that the Governor’s recommended boundary “includes the 

population most affected by high PM2.5 concentrations,” but lacks supporting information. See 

Table ES-1. In any event, the boundary of the nonattainment area must include areas that are 

experiencing violations of the air quality standard, as well as those nearby areas that contribute to 

those violations. In this case, the violations appear to be largely driven by emissions from cattle 

feedlots and agricultural activities that are inversely related to population density. As a result 

EPA concludes that population density is not significant factor in determining the geographic 

extent of the nonattainment area given the facts and circumstances of this particular area. 

Traffic and Commuting Patterns 

EPA and ADEQ agree that traffic and commuting patterns are not significant factors in 

determining the geographic extent of the nonattainment area given the facts and circumstances of 

this particular area. 
8 

Growth Rates and Patterns 

Because cattle feedlots, agriculture, and unpaved roads dominate the sources included in the 

emissions inventory that are contributing to violations in this area, EPA does not believe that 

growth rates and patterns are a significant factor with respect to determining the boundary of this 

nonattainment area. ADEQ, by pointing to the proximity of Indian country and publicly-owned 

lands as a buffer from contiguous development, reaches the same conclusion. 

Meteorology 

In developing its boundary decision, EPA also considered additional meteorological evidence 

submitted by ADEQ. Analyses performed by ADEQ are discussed in ADEQ technical report 

section 3.4 on Air Quality Data (pages 11 - 17) and in Appendix B. These included source 

apportionment, HYSPLIT trajectories, consideration of how a plume from a distant source would 

affect Cowtown and other monitors, comparison of concentrations between different 24-hour 

PM2.5 monitoring sites, and comparison of PM10 and PM2.5 temporal variation. Some of these 

analyses are similar to, and support, the conclusions reached by EPA discussed above, i.e. that 

Cowtown exceedances appear to be driven by a different mix of sources than those affecting the 

other monitoring sites in the area, with the dominant component caused by local sources. 

However, EPA does not believe these analyses provide sufficient basis for reducing the size of 

the nonattainment area proposed by EPA. EPA has already limited the boundary to a portion of 

Pinal County that contains the sources that appear to be contributing to the violations at the 

Cowtown monitor. Further reduction in the size of the boundaries would result in the exclusion 

of sources of the types that available evidence indicates contribute to the violations. 

The source apportionment data, based on the 2003 PCAQCD study using the Chemical Mass 

Balance model, provides evidence that feedlots are the most important emission source for 

Cowtown exceedances, and are responsible for 49% of the monitored value. Samples from other 

monitoring sites have a far lower proportion of feedlot emissions. ADEQ uses this as evidence of 

Cowtown's uniqueness, and also to support their position that emissions from feedlots are not 

widely transported. However, the same source apportionment analysis shows a soil contribution 

of 24% at Cowtown. This soil contribution may have come from locations beyond the 

immediate vicinity of the Cowtown monitor. In setting area boundaries, the CAA directs EPA to 

include locations that likely contribute to exceedances at the violating monitor(s). EPA does not 

believe that the 2003 PCAQCD source apportionment study supports a smaller area than that 

proposed by EPA. 

ADEQ also performed a back trajectory analysis using the HYSPLIT model for seven different 

PM2.5 exceedance days (ADEQ TSD Appendix B, pp.17-25). Air parcels arriving at the 

Cowtown monitor were traced back in time 6, 12, 18, and 24 hours to find their origin and to 

check for emission sources the parcels may have passed over. ADEQ concludes that in all cases 

there are no obvious PM2.5 sources along the transport path. It is not clear what criteria ADEQ 

applied to check for sources, but even if there are no apparent point sources, many of the 

trajectories do pass over agricultural land and over other areas of open land. Both agricultural 

and open land could be contributing PM10, PM2.5, and PM2.5 precursors to the air parcels arriving 

at Cowtown. For over half the trajectories, parcel arrival times (indicated by short line segments 
9 

on the graphs of hourly PM10 over time, which accompany each HYSPLIT map) correspond to 

elevated PM10 concentrations.6 EPA does not believe that the HYSPLIT evidence definitively 

proves or disproves the hypothesis of a local-only contribution to exceedances. Nor does EPA 

believe that the HYSPLIT analyses undermine the area boundary proposed by EPA.

Appendix B of ADEQ’s technical report also discusses (pages 26 - 32) the width of a plume 

from a hypothetical source 100 kilometers away, showing that it would be so wide by the time it 

reached Cowtown and Casa Grande, that it would likely affect monitors at both locations. 

ADEQ points out that this analysis is inconsistent with the fact that only the Cowtown monitor 

experiences exceedances. ADEQ presents the plume analysis as evidence that medium- and 

long-range transport are not responsible for the Cowtown exceedances. EPA agrees that this 

analysis provides some indication of the lack of difference in monitor impact from a somewhat 

distant point source. However, the longest dimension of EPA’s final boundary is approximately 

40 km, which is substantially less than the 100 km examined by ADEQ. Finally, EPA is not 

claiming that emissions from moderately distant locations dominate Cowtown concentrations, 

but rather that these emissions contribute to monitored violations of the air quality standard. 

Thus, EPA does not agree that the ADEQ analysis justifies reducing the final area boundary. 

Other analyses performed by ADEQ show that concentrations at Cowtown are statistically 

significantly different than those at other monitors (Appendix B, pages 28 - 31), and that there is 

a strong correlation between PM2.5 and PM10 at Cowtown (Appendix B, pages 32 - 34). EPA 

agrees with the findings that the same sources, likely local feedlots, constitute the major portion 

of both PM2.5 and PM10 emissions at the Cowtown monitor and supports the conclusion that 

Cowtown has a different mix of sources than the other 24-hour PM2.5 monitoring sites in 

Arizona. However, as shown by the source apportionment data and EPA's analysis of the diurnal 

variation of PM10 and wind speed for certain exceedance days where high PM10 is associated 

with high wind speed (e.g., 02-23-2007, 04-12-2007, 10-09-2007), there appears to be a soil 

contribution not associated with nearby feedlots, and there remains the potential for dust 

transport from moderately distant land. While ADEQ has presented evidence for a localized 

source causing the PM2.5 exceedances, EPA believes that there is some transport contribution 

from other locations within the final area boundary. 

Geography and Topography 

The ADEQ technical report section 3.3 (p.11) on Geography and Topography discusses the same 

mountain ranges discussed in the EPA TSD. EPA believes these mountain ranges are partial 

barriers to the transport of air pollution. Other than the Estrella Mountains to the north, ADEQ 

did not characterize these ranges as barriers to transport. However, the absence of barriers does 

not support an area smaller than that recommended by EPA. The ADEQ technical report also 

presents concentrations below the NAAQS at the Apache Junction and Casa Grande monitors 

and interprets this as evidence that the influence of emissions near Cowtown does not extend for 

 

6

 Hourly PM2.5 data are not available for the Cowtown site, but hourly PM10 data are. Because the PM2.5 at the 

Cowtown site is mainly from sources associated with primary PM10 (74% feedlot material and soil per ADEQ 

source apportionment), there is a correlation between 24-hour PM10 and PM2.5 levels at the Cowtown site. As a 

result, PM10 data can provide useful information about PM2.5. See page 26 of EPA’s TSD and Appendix B, page 11,

figure 6 of ADEQ’s technical report. 
10 

any significant distance from Cowtown. In setting area boundaries, however, EPA includes 

locations that may contribute to exceedances at Cowtown, rather than those locations without 

violating monitors to which Cowtown sources may contribute. EPA believes that the additional 

evidence presented by ADEQ for this factor does not support a smaller boundary area than 

proposed by EPA; however, upon further analysis we have concluded that the topography of the 

Table Top Wilderness Area would inhibit the transport of air pollution from the state lands 

located immediately to its south, and have revised the nonattainment area boundary accordingly. 

Jurisdictional Boundaries 

The State, lacking jurisdiction over tribal lands, properly excludes Indian country from its 

recommended nonattainment area. It also notes that, “since the violating monitor lies within the 

boundaries of the City of Maricopa and near Casa Grande, the incorporated boundaries of these 

municipalities were taken into account. The [State’s] recommended nonattainment area includes 

almost all of the City of Maricopa and excludes all of Casa Grande.” 

The northern portion of the eastern boundary of EPA’s nonattainment area partially coincides 

with Arizona’s proposed boundary. However, EPA’s boundary includes all state lands within 

T5S, R4E, whereas Arizona’s proposed boundary excludes section 12, 13, 24, and 25 of T5S, 

R4E. Although ADEQ’s technical report does not explicitly make the connection, it appears that 

these sections were excluded out in order to avoid including portions of Casa Grande in the 

nonattainment area. 

Because the sources that are the primary contributors to PM2.5 are regulated by the State and 

County, rather than by municipalities, EPA does not believe the inclusion of a portion of Casa 

Grande within the nonattainment area (or conversely, the exclusion of a portion of the City of 

Maricopa as Arizona has proposed), presents jurisdictional challenges. Further, municipal 

boundaries are subject to change. As a result, in this case EPA does not believe that municipal 

boundaries are a major factor in determining the boundary of the nonattainment area. By 

including all state lands within T5S, R4E, additional agricultural lands, some of which lie within 

Casa Grande’s incorporated boundaries, are included in the nonattainment area.

Level of Control of Emissions Sources

EPA noted in our TSD that we were not aware of any information regarding emissions controls 

that would have relevance to assessing source contribution to the monitored violations. As a 

result, the level of control of emissions sources was not considered to be a factor in determining 

the boundary of the nonattainment area. ADEQ’s technical analysis presented general 

information regarding air quality modeling and monitoring, and permitting and inspection 

programs, but did not use that information to support its proposed boundary. 

Conclusion

Based on our review of the Governor July 19, 2010 letter and ADEQ’s technical report, EPA has 

made a revision to the southwestern portion of the originally proposed nonattainment boundary. 

We have determined that the Table Top Wilderness Area, which occupies most of the 
11 

southwestern corner of our proposed nonattainment area, along with state lands to the south of 

the wilderness area, are not likely to cause or contribute to the exceedances measured at the 

Cowtown monitor. As a result, the final nonattainment area boundary excludes this area. Figures 

4-A and 6-A illustrate the revision to the nonattainment area boundary. 
12 

Figure 3-A. Emissions Sources and Revision to EPA’s Proposed PM2.5 Nonattainment Area Boundary. 

Tohono O'Odham

Tribal Lands

Table Top

Wilderness Area

West Central Pinal

PM2.5 Nonattainment Area - FINAL

PinalCounty

MaricopaCounty

7S 2E

8S 2E 8S 3E

7S 3E

6S 2E 6S 3E

7S 1E8S 1E6S 1E9S 1E 9S 2E 9S 3E 

8

347

0 2 1 Miles

AIR1000054_6a 28 October 

Sources: Arizona Geodata PortEPA (2010), ESRI (2010) TANA 

Additional Cattle OperaFeedlotsDairiesFinal EPA PM-2.5 NAAProposed EPA PM-25 NUnpaved RoadsAgricultureWildernessTownship and RangeTribal landsCounty boundary

PinalCounty
13 

Figure 4-A. Detail of Revision to EPA’s Proposed PM2.5 Nonattainment Area Boundary. 

Tohono O'Odham

Tribal Lands

Table Top

Wilderness Area

West Central Pinal

PM2.5 Nonattainment Area - FINAL

7S 2E8S 2E 8S 3E

7S 3E 7S 1E

8S 1E

6S 3E 6S 2E

6S 1E9S 1E 9S 2E 9S 3E 

PinalCounty

MaricopaCounty

8

84

0 

AIR1000054_7a 28 October 2Sources: Arizona Geodata PortaEPA (2010), ESRI (2010) TANA (

Final EPA PM-2.5 NAAProposed EPA PM-25 Township and RangeSectionsQuarter Sections

PinalCounty
14 

Figure 5-A. Final West-Central Pinal PM2.5 Nonattainment Area and Sources of Emissions. 

West Central Pinal

PM2.5 Nonattainment Area - FINAL

PinalCounty

MaricopaCounty

G

Tr

Ak-Chin

Tribal Lands

8

238

347

238

347

0 2.5 Miles 5

AIR1000054_10 4 November 2010Sources: Arizona Geodata Portal (2010), AQS (2010)EPA (2010), USDA (2006), ESRI (2010) TANA (2006).

Additional Cattle OperationsFeedlotsDairiesViolating PM-2.5 monitorAttaining PM-2.5 monitorUnpaved Roads

Final EPA PM-2.5 NAAProposed ADEQ PM-2.5 NAAAgricultureDeferred Tribal LandsCounty boundaryIncorporated City Boundaries 
15 

Figure 6-A. Pinal County and West-Central Pinal PM2.5 Nonattainment Area. 

West Central PinalPM2.5 Nonattainment Area - FINAL

PinalCounty

PimaCounty

MaricopaCounty

GilCo

Gila River

AkChin

0 

2.5 

AIR1000054_8a 28 OctobSources: EPA (2010), ESRI ( TANA (2006).

ProposFinal ECounty Tribal