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IOWA

EPA’s Area Designations for the 

2008 Lead National Ambient Air Quality Standards

Introduction

EPA has revised the level of the primary (health-based) standard from 1.5 micrograms per cubic 

meter (μg/m3) to 0.15 μg/m3 measured as total suspended particles (TSP). EPA has revised the 

secondary (welfare-based) standard to be identical in all respects to the primary standard.

Pursuant to section 107(d) of the Clean Air Act, EPA must designate as “nonattainment”

those areas that violate the NAAQS and those nearby areas that contribute to violations. 

The table below identifies the portions of a county in Iowa that EPA intends to designate

“nonattainment” for the 2008 lead national ambient air quality standard (2008 Lead NAAQS). 

Table 1. Iowa Lead NAAQS Nonattainment Areas

Area

Iowa Recommended 

Nonattainment County

EPA‟s Designated 

Nonattainment Counties

Nonattainment area 

for 1978 Lead 

NAAQS

Pottawattamie County Pottawattamie County

(partial) defined as: 

North - Avenue G

South - 23rd Ave

East - N16th / S 16th

West - N 35th/ S 35th St.

Pottawattamie County 

(partial) defined as: 

North - Avenue G

South - 23rd Ave

East - N16th / S 16th

West - N 35th/ S 35th St.

None

Technical Analysis for Pottawattamie County, Iowa Nonattainment Area

This technical analysis for portions of Pottawattamie County identifies the area with a monitor 

that violates the 2008 Lead NAAQS and evaluates nearby sources for contributions to lead 

concentrations in ambient air in the area. EPA has evaluated the county based on the weight of 

evidence of the following factors recommended in EPA guidance:

Air quality in potentially included versus excluded areas;

Emissions and emissions-related data in areas potentially included versus excluded from 

the nonattainment area, including population data, growth rates and patterns, and 

emissions controls;

Meteorology (weather/pollutant transport patterns);

Jurisdictional boundaries (e.g., counties, municipalities, political subdivisions of the state, 

etc.); and

Other relevant information submitted to or collected by EPA.
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Figure 1 is a map of the area analyzed depicting the location and design value of the air quality 

monitor measuring a violation of the 2008 Lead NAAQS in Pottawattamie County, Iowa, and the 

potential sources of lead concentrations to ambient air which may be contributing to the violating 

monitor. 

On March 29, 2011, the State of Iowa recommended that portions of Pottawattamie County, 

Iowa, identified in Figure 2, be designated as “nonattainment” for the 2008 Lead NAAQS based 

on air quality data from 2009 through 2010. The state‟s recommendation1 was based on analysis 

of monitoring and modeling data. The IDNR‟s recommended nonattainment area uses 

conservative modeling and adds a factor of conservatism by extending the recommended 

boundaries beyond the area where the isopleths indicate that predicted lead concentrations in air 

are one-half the Lead NAAQS. 

Based on the technical analysis using currently available information described below, EPA is 

designating portions of Pottawattamie County as nonattainment for the 2008 Lead NAAQS. 

1. Air Quality Data 

This factor considers the lead design value (in μg/m3) for the air quality monitor in Council 

Bluffs, Pottawattamie County, Iowa, and the surrounding area based on data collected by the 

IDNR from November 3, 2009 to the present. A monitor‟s design value indicates whether that 

monitor attains a specified air quality standard; in this case the 2008 Lead NAAQS the level of 

which is 0.15 μg/m3. The design value for the monitor in Pottawattamie County is shown in 

Table 2.

Table 2. Pottawattamie County Air Quality Data

County

State

Recommended

Nonattainment?

Monitor

Name

Monitor 

Air

Quality 

System ID

Monitor

Location

Lead Design

Value

2009-2010

(μg/m3)

Pottawattamie Yes

Griffin 

Pipe 

Monitor

ID #191550011 8th Ave & 27 St 

(41.25425, -

95.88725

0.26

 

1

“Lead Nonattainment Boundary Recommendations, Council Bluffs, IA, Technical Support Document,” Iowa 

Department of Natural Resources, March 29, 2011.
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Figure 1. Pottawattamie County Lead Nonattainment Area

Douglas Co, NE Maint. Area
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Figure 2. State Recommended Lead NAAQS Nonattainment Area

Proposed 

Boundary

Ave 

G

23rd

Ave

N 

16th St / S16th St

N 

35th St / S 35th St

Proposed Boundary

Section Lines

Modeled NAAQS 

violation (pre PSD)

Modeled Contours

Source: “Lead Nonattainment Boundary Recommendations, Council Bluffs, IA, Technical Support Document,” Iowa Department of Natural Resources, March 29, 2011.
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A violation of the 2008 Lead NAAQS for the monitor listed in Table 2 above was measured by a 

monitor in Pottawattamie County, Iowa. Therefore, some area in the county and possibly 

additional areas in surrounding counties must be designated nonattainment. The absence of a 

violating monitor alone is not a sufficient reason to eliminate nearby counties as candidates for 

nonattainment status. Each area has been evaluated based on the weight of evidence of the eight 

factors (collectively combined into five like groupings) and other relevant information.

The violating monitor is depicted in Figure 3 below. The violating monitor is a Federal 

Equivalent Method (FEM) monitor in the predominant downwind direction, approximately 0.1 

miles from the Griffin Pipe Corporation Products (Griffin Pipe) facility. Data from the monitor 

from November 2009 through December 2010 have been quality assured by IDNR. As Table 3 

below indicates, the monitor violated the standard in six rolling three month periods in 2010.

Table 3. 3-Month Rolling Averages for Lead

Pottawattamie County Ambient Air Monitor

Dates 3-Month Rolling Average

(μg/m3)

2008 Lead NAAQS Violation

Nov ‟09 – Jan „10 0.10

Dec ‟09 – Feb „10 0.03

Jan – Mar 2010 0.07

Feb – Apr 2010 0.12

Mar – May 2010 0.14

Apr – Jun 2010 0.17 X

May – Jul 2010 0.20 X

Jun – Aug 2010 0.26 Maximum

Jul – Sep 2010 0.24 X

Aug – Oct 2010 0.25 X

Sep – Nov 2010 0.18 X

Oct – Dec 2010 0.14
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Figure 3. Location of Pottawattamie County Ambient Air Monitor for Lead

Source: “Lead Nonattainment Boundary Recommendations, Council Bluffs, IA, Technical Support Document,” 

Iowa Department of Natural Resources, March 29, 2011.

2. Emissions and Emissions-Related Data

Evidence of lead emissions sources in the vicinity of a violating monitor are an important factor 

for determining whether a nearby area is contributing to a monitored violation. For this factor, 

EPA evaluated county level emission data for lead.

Table 4 below shows total emissions of lead for sources greater than 0.1 tons per year (tpy) in 

and around the recommended Pottawattamie County nonattainment area. Emissions data were 

generally derived from the 2008 National Emissions Inventory, version 1.5 (NEI08V1.5). 

NEI08V1.5 was the most current version of the national inventory available in 2011 when these 

data were compiled for the designations process 

(http://www.epa.gov/ttn/chief/net/2008nei_v1/lead_facility_v1_5_final.xls).
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Table 4. Lead Emissions for Pottawattamie County

County

State

Facility in State

Recommended 

Nonattainment

Area?

Facility – Total Air 

Emissions (tpy)

Facility Total County 

Lead Emissions

(tpy)

Pottawattamie Iowa Yes 0.59 1 Griffin Pipe 1.21

Pottawattamie Iowa No 0.581

MidAmerican –

Walter Scott 

Energy Center 1.21

1

– NEI08V1

Both the Griffin Pipe facility and the MidAmerican – Walter Scott Energy Center (WSEC), a 

power plant approximately 5.5 miles south-southeast of Griffin Pipe and the violating lead 

monitor, reported lead emissions greater than 0.5 tpy. WSEC, depicted in relation to the Griffin 

Pipe facility and violating monitor in Figure 4 below, operates four coal-fired electric generating 

units. The coal used to fuel the electric generating units at WSEC naturally contains lead which 

is released into the atmosphere from the burning coal. IDNR conducted modeling for this 

facility and requested a waiver from lead monitoring in its 2010 Network Monitoring Plan

(IDNR 2010). As discussed in Section 9.0, Other Relevant Information, modeling for the 

nonattainment area recommendation demonstrates the WSEC facility does not contribute to the 

Lead NAAQS violation at the monitor. The modeled contribution of WSEC to the 

nonattainment area was 0.0006 μg/m3 which is less than 1% of the Lead NAAQS.

There is one airport facility in Douglas County, Nebraska, which is directly north of the Griffin 

Pipe facility, with aircraft using leaded aviation gas that emits 0.1 tpy of lead. It is the Eppley 

Airfield (KOMA) in Figure 4 below. The state did not provide analyses (such as air quality 

modeling) to examine the potential impact of this airport on the violating monitor.2 

 

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There are approximately 20,000 airport facilities in the U.S. at which leaded aviation gasoline is consumed. 

Leaded aviation gasoline is used almost exclusively in piston-engine aircraft. Emissions data from the 2008 

National Emissions Inventory version 1 (NEI08V1) is the most accurate depiction for the airport facilities in the 

United States, and NEI08V1 data was used in evaluating emissions from these facilities.
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Figure 4. Omaha – Council Bluffs Area Lead Sources

3. Population Data, Growth Rates and Patterns

Table 5 shows the 2008 population for Pottawattamie County, Iowa, which includes the 

proposed nonattainment area. These data help assess the extent to which the concentration of 

human activities in the area and concentration of population-oriented commercial development 

may indicate emissions-based activity contributing to elevated ambient lead levels. This may 

include ambient lead contributions from activities that would disturb lead that has been deposited 

on the ground or on other surfaces. Re-entrainment of historically deposited lead typically is not 

reflected in the emissions inventory.
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Table 5. Population Data

County State Recommended 

Nonattainment?

2008 

Population

2008

Population 

Density 

(pop/sq mi)

Population 

Change

2000-2008

Population

% Change 

2000-2008

Pottawattamie 

County, Iowa

Yes, partial 89,647 94 1682 2

Source: U.S. Census Bureau estimates for 2008 (http://www.census.gov/popest/datasets.html) 

This factor considers population growth for 2000-2008 in the area considered for the 

nonattainment designation. Table 5 above shows population and population growth for 

Pottawattamie County, Iowa. All population data is from the U.S. Census Bureau 

http://www.census.gov/popest/counties/CO-EST2008-popchg2000_2008.html. 

Population in Pottawattamie County grew a modest 2%. Population growth is not expected to 

correlate with increases in lead emissions. Significant changes in industrial activity within the 

county that would cause an increase in area lead concentrations are difficult to predict, but are 

not anticipated. EPA has considered the population growth rate for this area and does not 

believe that it affects the boundary determination. 

4. Emissions Controls

Under this factor, the existing level of control of emission sources is taken into consideration. 

The emissions data used by EPA in this technical analysis and provided in Table 4 above

represent emissions levels taking into account any control strategies implemented on stationary 

sources in Pottawattamie County before 2008. 

The Griffin Pipe facility has recently implemented air pollution control activities as a part of its 

Prevention of Significant Deterioration (PSD) permitting (IDNR 2011). The PSD project was 

required to resolve a significant (> 0.6 tpy) increase in lead emissions which occurred at the 

facility. Activities included: replacement of the existing wet scrubber system for the cupola 

furnace with a baghouse; addition of a second baghouse to control emissions from the 

magnesium inoculation and desulfurization processes; and installation of two new chemical 

storage silos, one for a chemical that will be added to the gas stream after exiting cupola and 

before the baghouse for sulfur dioxide control, and the other for a chemical to be added to the 

gas stream for the treatment of heavy metals in the baghouse. The air pollution control 

equipment was installed in order to demonstrate that the facility meets the Best Available 

Control Technology (BACT) criteria. The facility must also utilize a scrap management plan to 

control the amount of lead contained in the scrap metal it processes. The final PSD permit was 

issued on December 7, 2010. The baghouses have been operational since January 2011. 

Implementation of the PSD project is expected to greatly reduce lead air emissions.
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5. Meteorology

For this factor, EPA considered data from 32 years of National Weather Service average 

frequency of wind direction by season. The data on meteorology are depicted in Figure 5 below. 

These data may provide evidence of the potential for lead emissions sources located upwind of a 

violating monitor to contribute to ambient lead levels at the violation location.

Figure 5. Wind Direction Frequencies

The three-dimensional bar chart above shows the wind frequencies in eight directions for the 

four seasons. The chart frequencies reflect the directions from which the winds come. Based on 

Figure 5, it may be concluded that the wind originates predominately from the north-northwest 

(NNW) in the winter months and from the east-southeast (ESE) during summer months. 

In its analysis, IDNR used data from the nearest Automated Surface Observing System (ASOS) 

meteorological station located at Eppley Airfield (KOMA) in Omaha, Nebraska (IDNR 2011). 

KOMA is approximately 3 miles to the north-northwest (NNW) of Griffin Pipe monitor in 

Council Bluffs, Iowa. Based on the data from the ASOS meteorological station at KOMA, 

IDNR concluded that the predominant wind directions were NNW and south-southeast (SSE).

Wind direction appears to have a strong influence on lead concentrations at the violating 

monitor. IDNR‟s analysis concludes that on days when the 24-hour average lead concentrations 

exceed 0.15 μg/m3, winds are typically out of the SSE (IDNR 2011). Further, IDNR concluded 
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that winds from the NNW, which also occur frequently, are rarely measured on days for which 

high lead concentrations are measured in the air monitor.

6. Geography/Topography

The geography/topography analysis evaluates the physical features of the land that may have an 

effect on the air shed and, therefore, on the distribution of lead over the proposed Pottawattamie 

County nonattainment area.

Council Bluffs is located on the eastern banks of the Missouri River and extends eastward into 

Pottawattamie County. The topography of Pottawattamie County consists of flat river bottoms 

from three to 10 miles wide along the Missouri River. Bluffs extending 100 to 300 feet above 

the floodplain demark the extent of the generally flat river bottoms. Further east in 

Pottawattamie County the terrain transitions into areas of steep ravines and hills, followed by 

gently rolling prairie (IDNR 2011).

The proposed nonattainment area does not have any geographical or topographical barriers 

significantly affecting air pollution transport within its air shed. Therefore, this factor did not 

play a significant role in determining the nonattainment boundary.

7. Jurisdictional boundaries 

Existing jurisdictional boundaries may be helpful in determining a boundary for purposes of 

nonattainment designations, and for purposes of carrying out the governmental responsibilities of 

planning for attainment of the lead NAAQS and implementing control measures. These existing 

boundaries may include an existing nonattainment or maintenance area boundary, a county or

township boundary, a metropolitan area boundary, an air management district, or an urban 

planning boundary established for coordinating business development or transportation activities.

In the area surrounding the violating monitor, the proposed nonattainment area lies within the 

jurisdictional boundary of the City of Council Bluffs, Iowa. The City of Council Bluffs 

encompasses approximately 39.7 square miles(IDNR 2011). Based on the modeling data which 

are described in Section 9 below, IDNR recommended a nonattainment area that is considerably 

smaller than the city limits. Rather, the IDNR recommended nonattainment area is defined by

major roadways that it believes are durable and more recognizable to the public. This is 

reasonable considering the chemical properties of lead: elemental lead and lead compounds area 

heavier and tend to deposit from ambient air faster and in a shorter distance from the source than 

lighter molecular weight pollutants.

8. Other Relevant Information

EPA received additional information from the State relevant to establish a nonattainment area 

boundary for portions of Pottawattamie County, Iowa. As briefly mentioned above, IDNR 

submitted the results of a dispersion model analysis in support of its boundary 
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determination. EPA considered this information and conducted an independent analysis in 

making its boundary determination for the Pottawattamie County nonattainment area. 

In accordance with the Lead NAAQS Final Rule, the presumptive boundary of the nonattainment 

area is the entire county with a violating monitor. The State and/or EPA may conduct additional 

area-specific analyses that could lead to a departure from the presumptive boundary. 

Boundaries may be recommended on the basis of one or any combination of the following 

techniques in addition to the eight-factor analysis:

Qualitative analysis;

Spatial interpolation of air quality monitoring data; or

Air quality simulation by dispersion modeling.

IDNR elected to use dispersion modeling for making its boundary recommendation to EPA. 

EPA evaluated IDNR‟s analysis and conducted independent verification and analysis as 

discussed below.

IDNR used AERMOD, EPA‟s preferred dispersion model for the analysis conducted. The 

modeling was performed for two scenarios: absent baghouse controls using actual emissions 

rates based on stack testing conducted in March 2010; and with baghouse controls installed in 

January 2011 using BACT emissions limits specified in the facility‟s air construction permit for 

the PSD project. Emissions modeled under this scenario were 0.28 lbs lead per hour, or 1.23 tpy 

(IDNR 2011), which is approximately a factor of two greater than the facilities emissions 

reported emissions of 0.58 tpy listed above in Table 4.

Other potential sources of lead from the area, including power plants and cement kiln discussed 

in Section 2 above, were modeled based on potential to emit. The WSEC facility, which is 

approximately 5.5 miles from Griffin Pipe and the violating monitor, had the greatest 

contribution to the nonattainment area of all the Iowa and Nebraska sources of lead emissions 

modeled. The modeling determined that WSEC contributed 0.0006 μg/m3of lead to the receptor 

grid area, which is less than 1% of the level of the Lead NAAQS. Therefore, the modeling 

confirms that the Griffin Pipe facility is the source of lead measured at the violating monitor.

In IDNR‟s model scenario absent baghouse controls, violations of the NAAQS were predicted to 

extend approximately one-third mile to the north and one-fourth mile to the south from the

Griffin Pipe facility (Figure 6). The highest predicted lead concentration for this scenario, 0.60 

μg/m3, occurred along the southern boundary of the facility near the cupola stack. There is a 

sharp decrease in the lead concentrations as the distance from the facility increases, as would be 

predicted based on the physical properties of lead.

As Figure 7 below indicates, in the scenario with baghouse controls, the predicted lead 

concentrations are below the Lead NAAQS. The highest lead concentration predicted by the 

model in this scenario was 0.054 μg/m3. Concentrations of lead for the potential lead-emitting 

facilities remained the same in the scenario modeled with baghouse controls because the only 
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change in this scenario specifically relates to air pollution control equipment installed at the 

Griffin Pipe facility; the model inputs for the other facilities remained the same.

Using the outcomes of its modeling effort and its eight-factor analysis, the IDNR recommended 

boundaries for the Lead NAAQS nonattainment area depicted in Figure 2 above. The IDNR‟s 

recommended nonattainment area is based upon the use of the most conservative model run, the 

scenario absent baghouse controls, and adds a factor of conservatism by extending the 

recommended boundaries beyond the area where the isopleths indicate that predicted lead 

concentrations in ambient air are one-half the Lead NAAQS. 

EPA conducted an independent review of IDNR‟s model and determined the modeling effort 

was generally comprehensive and done in accordance with EPA modeling guidance (Daye 

2011). EPA‟s model output for the absent baghouse controls scenario is depicted in Figure 8 

below. 

Conclusion

EPA is designating portions of Pottawattamie County, Iowa which include the Griffin Pipe 

facility in Figure 2 as the nonattainment area for the 2008 Lead NAAQS. The boundaries of the 

proposed nonattainment area are based on major roadways in Council Bluffs, Iowa as follows: 

North - Avenue G

South - 23rd Ave

East - N16th / S 16th

West - N 35th/ S 35th St.

The air quality monitor in Pottawattamie County located NNW of the facility shows violations of 

the 2008 Lead NAAQS based on 2009 - 2010 air quality data. Therefore, a nonattainment 

designation is required for all or some of Pottawattamie County. The eight-factor analysis and 

other relevant information, including modeling results, supports a partial county designation for 

Pottawattamie County. 

Based on its consideration of all the relevant, available information, as described above, EPA 

believes that the boundaries described herein encompass the entire area that does not meet (or

that contributes to ambient air quality in a nearby area that does not meet) the 2008 Pb NAAQS. 
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Figure 6. IDNR Air Dispersion Model Results - Absent Baghouse Controls
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Figure 7. IDNR Air Dispersion Model Results – with Baghouse Controls
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Figure 8. EPA Air Dispersion Model Result – Absent Baghouse Controls
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References

“Iowa Ambient Air Monitoring 2010 Network Plan,” Iowa Department of Natural Resources, 

June 2010.

“Lead Nonattainment Boundary Recommendations, Council Bluffs, IA, Technical Support 

Document,” Iowa Department of Natural Resources, March 29, 2011.

Daye, Richard. Email correspondence to Stephanie Doolan, U. S. Environmental Protection 

Agency (EPA) Region 7, Air Planning and Development Branch, dated May 27, 2011.

Definition of important terms used in this document:

1) Designated “nonattainment” area – an area which EPA has determined, based on a State 

recommendation and/or on the technical analysis included in this document, has violated the 

2008 Lead NAAQS, based on the most recent three years of quality assured air quality 

monitoring data from 2008-2010 including at least one valid three-month site mean above the 

level of the 2008 Lead NAAQS, or that contributes to a violation in a nearby area. 

2) Designated “unclassifiable/attainment” area – an area which EPA has determined does not 

contribute to a violation of the 2008 Lead NAAQS in a nearby area and either: (1) meets the 

2008 Lead NAAQS, based on the most recent three years of quality assured air quality 

monitoring data from 2008-2010 including 36 consecutive valid three-month site means 

(including the last two months of 2007), or (2) has no monitors or has incomplete air quality 

monitoring data for 2008-2010 but has no violations of the 2008 Lead NAAQS.

3) Designated “unclassifiable” area – an area which EPA has determined cannot be classified 

on the basis of available information as meeting or violating the 2008 Lead NAAQS, based on 

the most recent three years of quality assured air quality monitoring data from 2008-2010, but for 

which available monitoring data from the same or a recent period indicate a significant 

likelihood that the area may be violating the 2008 Lead NAAQS.

4) Violating monitor – an ambient air monitor whose valid design value exceeds 0.15 

micrograms per cubic meter (ug/m3). As described in Appendix R of 40 CFR part 50, a violation 

can be based on either Pb-TSP or Pb-PM10 data and only three months of data are necessary to

produce a valid violating design value. 

5) 1978 Lead NAAQS – 1.5 μg/m3, National Ambient Air Quality Standard for lead 

promulgated in 1978. Based on Pb-TSP indicator and averaged over a calendar quarter.

6) 2008 Lead NAAQS - 0.15 μg/m3, National Ambient Air Quality Standard for lead 

promulgated in 2008. Based on Pb-TSP indicator and a three-month rolling average. Pb-PM10 

data may be used in limited instances, including to show nonattainment.