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Davenport-Moline-Rock Island, IL-IA

Area Designation for the 

2012 Primary Annual PM2.5 National Ambient Air Quality Standard

Technical Support Document

Summary

In accordance with Section 107(d) of the Clean Air Act (CAA), the EPA must promulgate 

designations for all areas of the country. In particular, the EPA must identify as “nonattainment”

those areas that are violating a National Ambient Air Quality Standard (NAAQS) or contributing 

to a violation of the NAAQS in a nearby area. Additionally, through the designation process, the 

EPA identifies areas that are meeting the NAAQS and those areas without sufficient data for the 

Agency to make a determination. The EPA uses a designation category of

“unclassifiable/attainment” for areas where air quality monitoring data indicate attainment of the 

NAAQS and for areas that do not have monitors but for which the EPA has reason to believe are 

likely to be in attainment and are not contributing to nearby violations. The EPA reserves the 

category of “unclassifiable” for areas where the EPA cannot determine based on available 

information whether the area is meeting or not meeting the NAAQS or where the EPA has not 

determined that the area contributes to a nearby violation. The EPA must complete this process 

within 2 years of promulgating a new of revised NAAQS, or may do so within 3 years under 

circumstances not relevant to these designations.1

This technical support document (TSD) describes the basis for EPA’s decision to designate the 

Scott County portion of the Davenport area in Iowa as unclassifiable/attainment and the Rock 

Island, Henry, and Mercer County portions of the Davenport area in Illinois as unclassifiable for 

the 2012 primary annual fine particle NAAQS (2012 annual PM2.5 NAAQS).2 

Consistent with section 107(d), states were required to submit area designation recommendations 

to the EPA for the 2012 annual PM2.5 NAAQS no later than 1 year following promulgation of the 

standard, or by December 13, 2013. On December 12, 2013, Illinois recommended that Rock 

Island, Henry and Mercer Counties be designated as unclassifiable/attainment for the 2012 

annual PM2.5 NAAQS, based on air quality data from 2010 to 2012. On April 30, 2014, Iowa 

recommended a designation of unclassifiable/attainment for Scott County.

After considering these recommendations and based on EPA’s technical analysis as described in 

this TSD, the EPA is designating Scott County in Iowa as “unclassifiable/attainment” and Rock 

Island, Henry, and Mercer Counties in Illinois as “unclassifiable” for the 2012 annual PM2.5

 

1 Section 107(d) of the CAA requires the EPA to complete the initial designation process within 2 years of 

promulgation of a new or revised NAAQS, unless the Administrator has insufficient information to make initial 

designation decisions in the 2-year time frame. In such circumstances, the EPA may take up to 1 additional year to 

make initial area designation decisions (i.e., no later than 3 years after promulgation of the standard).

2 On December 14, 2012, the EPA promulgated a revised primary annual PM2.5 NAAQS (78 FR 3086, January 15, 

2013). In that action, the EPA revised the primary annual PM2.5 standard, strengthening it from 15.0 micrograms per 

cubic meter (μg/m3) to 12.0 μg/m3.
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standards. These designations for the four counties in the Davenport area are listed in Table 1. 

The EPA must designate an area nonattainment if it has an air quality monitoring site3that is 

violating the standard or if it has sources of emissions that are contributing to a violation of the 

NAAQS in a nearby area. No monitoring data indicate nonattainment of the 2012 annual PM2.5

standards in the Davenport area.

A recent EPA-conducted technical systems audit of the weighing of PM2.5 samples in Illinois 

revealed that the Cook County Department of Environmental Control, which weighs all of the 

filters in Illinois’ monitoring network, did not have appropriate equipment for determining 

whether the laboratory conditions met the temperature and humidity criteria in 40 CFR 50 

Appendix L for proper conditioning of filters, and the instantaneous temperature and humidity 

information suggested that many of the weighings failed to meet these criteria.4 As a result, the 

EPA believes that no monitoring site in Illinois has sufficient valid data to support a 

determination of either nonattainment or attainment, and therefore, the EPA cannot rely directly 

upon analysis/recommendations the states performed/provided which partially rely upon this 

invalid monitoring data. Thus, the EPA cannot determine whether any area in Illinois is meeting 

or not meeting the NAAQS.

Table 1. Illinois’ and Iowa’s Recommended Designations and EPA’s Designations for the 

Davenport Area for the 2012 annual PM2.5 NAAQS

Area of Analysis Illinois’ and Iowa’s 

Unclassifiable/attainment 

Recommendations

EPA’s Designations

Davenport-MolineRock Island, IL-IA

Illinois: Rock Island, 

Henry and Mercer

Counties

Iowa: Scott County

Illinois: Rock Island – Unclassifiable

Henry – Unclassifiable

Mercer − Unclassifiable

Iowa: Scott County –

Unclassifiable/attainment 

Illinois’ recommendations for other counties in the state outside of the Davenport area are 

addressed in a separate TSD.5 The EPA agrees with Iowa’s recommendations that all counties 

 

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In accordance with 40 CFR 50 Appendix N, PM2.5 measurements from the primary monitor and suitable collocated 

PM2.5 FRM, FEM or ARMs may be used in a “combined site data record” to establish a PM2.5 design value to 

determine whether the NAAQS is met or not met at a particular PM2.5 monitoring site.

4 Memorandum from Liz P. Naess, Air Quality Assessment Division, US EPA Office of Air Quality Planning and 

Standards, to EPA Docket EPA-HQ-OAR-2012-0918, Air Quality Designations for the 2012 PM2.5 Standards, titled, 

“Data Issues in Illinois Affecting Air Quality Designations for the 2012 PM2.5 National Ambient Air Quality 

Standards.”

5 Technical Support Document, December 2014, titled, “Illinois Unclassifiable Area Designations for the 2012 

Primary Annual PM2.5 National Ambient Air Quality Standards,” prepared by US EPA.
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and portions of counties in Iowa should be designated as “unclassifiable/attainment,” including 

those in the Davenport area.

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Technical Analysis for Davenport-Moline-Rock Island, IA-IL

The Davenport-Moline-Rock Island, IA-IL MSA includes Rock Island, Henry and Mercer 

Counties in Illinois and Scott County in Iowa. Both Illinois and Iowa recommended a 

designation of unclassifiable/attainment for their counties within this area. The core of the urban 

area of Davenport, where the majority of the emissions and emissions activities are located,

consists of Scott County, Iowa and Rock Island County, Illinois. As explained above, the EPA is

designating all of Illinois unclassifiable. However, the EPA evaluated whether the Iowa portion 

of the Davenport-Moline-Rock Island, IA-IL MSA could be contributing to a potential violation 

of the NAAQS in the Illinois portion of this MSA. As part of this analysis, the EPA considered 

information relevant to a five factor analysis for the Iowa portion of the MSA. Below is a 

discussion of the factor-related information generally considered for evaluating appropriate 

boundaries for a nonattainment area. These factors include: Air Quality Data; Emissions and 

Emissions-related Data; Meteorology; Geography/Topography; and Jurisdictional Boundaries.

For the first factor, the EPA considers air quality information for the area. As shown in Figure 1, 

the Iowa portion of the Davenport area currently has four PM2.5 monitors located in Scott

County, Iowa. All four monitors have complete and valid data showing attainment of the 2012 

PM2.5 NAAQS, with 2011-2013 design values ranging from 10.2 to 10.7 μg/m3. As noted above, 

although the monitor located in Rock Island County, Illinois does not have current, reliable 

monitoring data, this monitor has historically measured annual values below the Scott County, 

Iowa monitors (see historical design value trend chart in Figure 2), suggesting that it is unlikely 

there is a current violation of the NAAQS in the area. However, given the questions concerning 

the validity of the monitor data the EPA cannot exclusively rely on this fact, but this information 

can add to the weight of evidence supporting the EPA’s conclusions regarding appropriate 

designations for the area. Table 2 shows the recent design value history for the four valid, 

attaining monitors located in Scott County, Iowa.

 

6 Unless a state or tribe has specifically identified jurisdictional boundaries in their area recommendations, when 

determining “remainder of the state,” the EPA will use Federal Information Processing Standard (FIPS) codes 

maintained by the National Institute of Standards and Technology (NIST), which are used to identify counties and 

county equivalents (e.g., parishes, boroughs) of the United States and its unincorporated territories (e.g., American 

Samoa, Guam, Northern Mariana Islands, Puerto Rico, and the US Virgin Islands). Available on EPA’s Envirofacts 

website at http://www.epa.gov/envirofw/html/codes/state.html.
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Table 2. Air Quality Data collected at Regulatory Monitors in Davenport (all DV levels in μg/m3)

State County Monitor ID

State 

Recommended 

Nonattainment?

PM2.5 Annual 

Design Value 

2009-2011

PM2.5 Annual 

Design Value 

2010-2012

PM2.5 Annual 

Design Value 

2011-2013

Iowa Scott 191630015 No 11.4 11.0 10.2

Iowa Scott 191630018 No 11.5 11.2 10.4

Iowa Scott 191630020 No 11.3 10.7

Iowa Scott 191630019 No 10.6

Historically, the Davenport area has not violated any annual PM2.5 standards, and thus the EPA 

has not previously established a nonattainment boundary for this area. In the absence of a 

previously established nonattainment boundary, the EPA has considered relevant information to 

assess the possibility of contribution to a potential violation of the NAAQS in the Illinois portion 

of the MSA, and whether that contribution is likely to be significantly different from the 

contribution to the valid, attaining monitors in Scott County. Figure 1 shows the Davenport area 

MSA along with the locations of area monitors. The valid monitors in Scott County, Iowa are 

shown with blue dots, while the location of the invalid Rock Island, Illinois monitor is depicted 

by an orange star.

Figure 1. Map of MSA Boundary for Davenport with monitor locations
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Note: Rock Island PM2.5 monitor 171613002 location is shown as a star in Figure 1.

Figure 2. Davenport PM2.5 Design Value Trends 2003-2013 (μg/m3)

Note: Monitor ID 171613002 – All recent design values at this site in Illinois are invalid.

Recent population data for the Davenport area indicate similar population in Illinois and Iowa, 

with 2010 Rock Island County population of 147,612 and 2010 Scott County population of 

165,781. While Henry and Mercer Counties in Illinois have an additional population of 66,850

combined, the population density in these counties is much less than the two core counties of 

Rock Island and Scott. Table 3 shows Davenport area population and population density for both 

2000 and 2010.

Table 3. Population Growth and Population Density.

State County

FIPS 

Code

Population 

2000

Population 

2010

% Change 

from 2000

Land Area 

(Sq. Miles)

Population 

Density (per 

Sq. Mile)

IL Henry 17073 51,020 50,424 -1.2% 823.2 61.3

IL Mercer 17131 16,957 16,428 -3.1% 561.0 29.3

IL Rock Island 17161 149,374 147,612 -1.2% 426.8 345.9

IA Scott 19163 158,668 165,781 4.5% 457.9 362.0

Several industrial facilities are located in the Davenport area: the MidAmerican Energy 

Riverside Station (located in the eastern portion of Scott County near the Mississippi River), 

Alcoa (located east of monitors in Scott County and east-northeast of the Rock Island County 

monitor), Lafarge North America, Inc. (located in the Southwest portion of Scott County and to 

the southwest of all area monitors), and John Deere Harvester Works (located in Rock Island 

County south of the MidAmerican Energy plant noted above and generally east of all area 

monitors). Figure 3 shows the location of these point sources in relation to the monitoring site

locations (blue dots represent the valid, attaining Scott County, Iowa monitors, while the orange 

9.0

10.0

11.0

12.0

13.0

14.0

15.0

16.0

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Design Value Trends 2003-2013 

191630015 191630018 191630019

191630020 171613002 NAAQS
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star represents the Rock Island, Illinois monitor with invalid data). Table 4 summarizes the 2011 

reported emissions from these point sources. Emissions from each of these stationary sources is 

relatively low, with the highest being approximately 1,511 tons per year of NOx and 3,694 tons 

per year of SO2 from the MidAmerican Energy Riverside Station. 

Figure 3. Point Sources Located in the Davenport Area

Note: Rock Island PM2.5 monitor 171613002 location is shown as a star in Figure 3.

Table 4. NEI 2011 v1 Point Source Emissions (tons/year) 

State County Facility Name NH3 NOX PM2.5 SO2 VOC

IL Henry ANR Pipeline Co* 0 1,007 11 0 54

IL Rock Island John Deere Harvester Works 8 172 6 978 119

IA Scott MIDAMERICAN ENERGY CO - RIVERSIDE STATION 1 1,511 95 3,694 18

IA Scott ALCOA INC 6 159 156 5 240

IA Scott LAFARGE NORTH AMERICA, INC 5 1,605 57 1,527 130

* Located in Illinois outside the core Davenport area view in Figure 3 and not further assessed here.
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Overall emissions are similar in the Iowa and Illinois counties in the Davenport area with 

population-related and mobile source emissions in the core areas at the same order of magnitude. 

Table 5 provides a summary of the overall direct PM2.5 and PM2.5 precursor emissions in 2011. 

The aggregate emissions of direct PM2.5 and precursor pollutants from the Davenport area point 

sources are slightly higher in Scott County and comprise a significant portion of Scott County’s 

NOx and SO2 emissions, but are from sources generally located in an area which would be no 

more likely to impact the Rock Island monitor portion of the Davenport area than the four Scott 

County monitors, based on the meteorological data. 

Table 5. County-Level Emissions of Directly Emitted PM2.5 and Precursors (tons/year)

State County NH3 NOX VOC SO2 PM2.5

Illinois Henry Co 2,557 4,382 2,319 60 1,720

Illinois Mercer Co 1,311 687 953 33 910

Illinois Rock Island Co 779 4,237 4,339 1,433 1,051

Illinois

Rock Island Co % from single 

point source in Table 4 <1% 4% <1% 68% 11%

Iowa Scott Co 1,935 7,124 5,884 5,349 2,233

Iowa

Scott Co % from the three

point sources in Table 4 <1% 46% 5% 98% 17%

A review of the meteorological data for the Davenport area indicates winds most frequently from 

the south, east and west with a smaller northwest component. Figure 4 shows wind roses that the 

EPA generated from the Davenport Municipal Airport located in the northern portion of the 

urban area and the Quad City International Airport in the southern portion of the urban area 

using 2009-2012 data from National Weather Service locations archived at the National Climate 

Data Center.7 The most frequent wind directions are from the west-northwest, the south and the 

east. The least frequent winds are from the north, northeast and southwest. 

Although the wind data suggest that there could be some contribution from sources in Scott 

County to the Rock Island portion of the Davenport area, much of the emissions and emissions 

activity in Scott County, including key point sources identified in Table 4, comes from sources 

located to the north and northeast of the monitor in Rock Island and thus there is less likely to be 

contribution from such sources. Given these wind direction frequencies, the Scott County 

sources would not likely differentially impact the Rock Island monitor (relative to the Scott 

County monitors that currently indicate attainment of the 2012 PM2.5 NAAQS by a significant 

margin). The historical PM2.5 data in Figure 2 lends additional support to this notion.

 

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ftp.ncdc.noaa.gov/pub/data/noaa or 

http://gis.ncdc.noaa.gov/map/viewer/#app=cdo&cfg=cdo&theme=hourly&layers=1&node=gis. Quality assurance 

of the National Weather Service data is described here: http://www1.ncdc.noaa.gov/pub/data/inventories/ish-qc.pdf
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Figure 4. Wind Roses Representing the Area of Analysis for the Davenport Area.

Note: Rock Island PM2.5 monitor 171613002 location is shown as a star in Figure 4.

Conclusion

Based on this technical analysis, the EPA agrees with Iowa’s recommendation and is designating

Scott County, Iowa as unclassifiable/attainment with the remaining three counties in the Illinois 

portion of the MSA (Rock Island, Henry and Mercer) designated as unclassifiable. The EPA is

designating all other counties in Iowa as unclassifiable/attainment as recommended by Iowa.