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MICHIGAN

Area Designations For the 

2008 Lead National Ambient Air Quality Standards

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 partial county in Michigan that EPA intends to designate

“nonattainment” for the 2008 lead National Ambient Air Quality Standard (2008 lead NAAQS).

Area Michigan Recommended 

Nonattainment County

EPA’s Designated 

Nonattainment County

Belding Ionia (partial) Ionia (partial)

Table 1: Michigan Nonattainment Area for the 2008 Lead NAAQS

Technical Analysis for Belding

Introduction 

This technical analysis for Belding identifies the partial county with a monitor that violates the 

2008 lead NAAQS, and evaluates nearby counties for contributions to lead concentrations in the 

area. EPA has evaluated these counties based on the weight of evidence of the following factors 

recommended in previously issued 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/transport patterns);

Geography/topography (mountain ranges or other air basin boundaries);

Jurisdictional boundaries (e.g., counties, air districts, reservations, etc.); and,

Any other relevant information submitted to or collected by EPA.
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Figure 1: Belding, Michigan State Recommended Nonattainment Area 

(Office of Air Quality and Planning Standards - OAQPS)

Figure 1 is a map of the area analyzed showing the locations and design values of air quality 

monitors in the area, and the counties surrounding any violating air quality monitors. Source 

data is also labeled in Figure 1 with the following guidelines: if the source emitted 0.50 or more 

tons per year (tpy), the symbol, name of the facility, and emissions are labeled; if the source 

emitted 0.10 – 0.50 tpy, only the symbol and emissions are labeled; and if the source emitted less 

than 0.05 tpy, only the symbol is shown.1 Emissions in Belding and the surrounding areas will 

be discussed in the section addressing emissions in Ionia County. The location of the detailed 

area in relation to the remainder of the State is shown in the bottom right corner of the figure.

 

1 Emissions greater than 0.05 tpy round up to 0.10 tpy, and they are marked with the symbol and the emissions 

value. 
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Figure 2: Belding, Michigan State Recommended Nonattainment Area Local View (OAQPS)

In a similar manner, Figure 2 shows the locations and design values of air quality monitors in the 

area, but on a localized view focusing on the area of the violating monitor. Again, source data is 

labeled with the following guidelines: if the source emitted 0.50 or more tpy, the symbol, name 

of the facility, and emissions are labeled; if the source emitted 0.10 – 0.50 tpy, only the symbol 

and emissions are labeled; and if the source emitted less than 0.05 tpy, only the symbol is shown.
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Figure 3: Belding, Michigan State Recommended Nonattainment Area (Google Earth)

Figure 3 shows the State recommended nonattainment area boundary for Belding, Michigan. 

The boundary is shown with the red outline, and is enclosed by the following boundary points, 

provided by the State. 

Boundary Location Longitude Latitude

Southeast Corner -85.2130771 43.0956705

Southwest Corner

(Intersection of S. Broas St. 

and W. Washington St.) -85.2324027 43.0960358

Northeast Corner -85.2132313 43.1074942

Western Boundary 1

(Intersection of W. Ellis St. and the vertical 

extension of S. Broas St.) -85.2322553 43.1033277

Western Boundary 2

(Intersection of W. Ellis St. and N. Bridge St.) -85.2278464 43.1033911

Western Boundary 3

(Intersection of N. Bridge St. and Earle St.) -85.2279722 43.1074479

Table 2: Belding, Michigan State Recommended Nonattainment Area Boundary Points

In December 2010, Michigan recommended that portions of Ionia County be designated as 

nonattainment for the 2008 lead NAAQS based on monitored air quality data collected between 

2008 and 2010. The State’s recommendation was based on data from Federal Reference Method 

(FRM) or Federal Equivalent Method (FEM) monitors located in Michigan. Rebecca 
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Humphries, Director of the Michigan Department of Environmental Quality (MDEQ)2, 

submitted the State’s recommendation to EPA in a letter dated December 10, 2010. 

On June 15, 2011, EPA notified the State of Michigan of our proposed decision to accept the 

State’s recommended nonattainment designation and associated boundaries. EPA also asked that 

if the State had additional information that it wanted EPA to consider with respect to the 

proposed nonattainment area and associated boundaries, the State submit this information by 

August 15, 2011. EPA received no additional information from the State of Michigan.

On June 21, 2011, EPA published a Federal Register notice notifying the public that we had 

posted our responses to States’ recommendations for the 2008 lead NAAQS (76 FR 36042). 

This same notice simultaneously opened a comment period inviting the public to comment on 

our responses to States’ recommendations. During the public comment period, which ended on 

July 21, 2011, we received no comments at all with respect to the nonattainment designation and 

associated boundaries for the Belding area. 

Based on EPA’s technical analysis described below, EPA is designating portions of Ionia County 

in Michigan as nonattainment for the 2008 lead NAAQS as part of the Belding nonattainment 

area based upon currently available information. This county is listed above in Table 1.

Detailed Assessment

Air Quality Data 

This factor considers the lead design values (in μg/m3) for air quality monitors in Ionia County in 

Belding and the surrounding area based on data for the 2008 – 2010 period. A monitor’s design 

value indicates whether that monitor attains a specified air quality standard. The 2008 lead 

NAAQS are met at a monitoring site when the identified design value is valid and less than or 

equal to 0.15 μg/m3. A design value is only valid if minimum data completeness criteria are met. 

A lead design value that meets the NAAQS is generally considered valid if it encompasses 36 

consecutive valid 3-month site means (specifically for a 3-year calendar period and the 2 

previous months). For this purpose, a 3-month site mean is valid if valid data were obtained for 

at least 75 percent of the scheduled monitoring days in the 3-month period. A lead design value 

that does not meet the NAAQS is considered valid if at least one 3-month mean that meets the 

same 75 percent requirement is above the NAAQS. That is, a site does not have to monitor for 3 

full calendar years in order to have a valid violating design value; a site could monitor just 3 

months and still produce a valid (violating) design value.

 

2 At the time of its December 2010 submittal, MDEQ was a part of the Michigan Department of Natural Resources 

and Environment, but has since then reverted back to MDEQ. 
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County State 

Recommended

Nonattainment?

Monitor Name Monitor Air 

Quality 

System ID

Monitor Location Lead Design 

Value, 

2008-2010

(μg/m3)

Ionia, 

Michigan

Yes Mueller 

Industries

260670003 509 Merrick St.

(43.09994, 

-85.22227)

0.28

The monitor in bold has the highest 2008 - 2010 design value in the respective county.

Table 3: Belding, Michigan and Surrounding Area Air Quality Data

The 2008 lead NAAQS design values for Ionia County in Belding and the surrounding area are 

shown in Table 3, and a monitor in Ionia County violates the 2008 lead NAAQS. Therefore,

some area in this 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 these factors and other relevant information. 

The monitor located at 509 Merrick St. (AQS ID 260670003) has an objective of determining the 

highest concentration for lead. This monitor is in very close proximity to Mueller Industries. 

The location of this monitor will be discussed in the section addressing emissions for Ionia

County. 

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 and any growth in lead emitting activities

since the date represented by those emissions data.

Emissions

Emissions data for industrial were derived from the 2008 National Emissions Inventory, version 

1.5 (NEI08V1.5), which was the most current version of the national inventory available in 2011 

when these data were compiled for the designations process.3 See 

http://www.epa.gov/ttn/chief/net/2008nei_v1/lead_facility_v1_5_final.xls. EPA recognizes that

for certain counties, we have no information on any emissions increases or decreases that may 

have occurred since 2008. For example, certain large sources of emissions in or near this area 

may have installed emission controls or otherwise significantly reduced emissions since 2008. 

Some States provided updated information on emissions and emission controls in their comments 

to EPA. Michigan provided emissions data in its December 2010 submittal that is consistent 

with the NEI08V1.5 and NEI08V1data. These data are provided in Table 4.

Table 4 shows total emissions of lead for violating and potentially contributing counties in and 

around Belding and sources emitting (or anticipate to contribute) 0.1 tpy or greater of lead 

 

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

fuel 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 in Ionia County.
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according to the NEI08V1.5 and NEI08V1. The county that is part of the Belding nonattainment 

area for the 2008 lead NAAQS is shown in boldface. 

County

Facility in State 

Recommended 

Nonattainment 

Area? Facility Name

NEI08V1.5

(tpy) Location City

Ionia County, 

Michigan Yes Mueller Industries 0.8 302 Ashfield St. Belding

Ionia County Total

Lead Emissions 0.8*

Table 4: Belding, Michigan and Surrounding Areas Lead Emissions for Stationary Sources

* Total lead emissions for Ionia County were calculated by adding all emissions from the county, including those 

from facilities using leaded aviation gas. 

As seen in Figure 1 and Figure 2, there are several airport facilities in the Belding area that use 

leaded aviation gasoline. However, the most recent emissions data for airports using leaded 

aviation gasoline indicates that the emissions are below 0.1 tpy. 

Figure 4: Mueller Industries Monitor Location (Google Earth)

Mueller Industries accounts for virtually all of the lead emissions in Ionia County; as a result, the 

Belding nonattainment area should include the Mueller Industries facility in its entirety. Figure 4 

shows the location of Mueller Industries (red star) and the monitor associated with this facility 

(yellow pin). The distance between the center of the facility and the monitor is approximately 
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340’, or 0.07 miles. The monitor was deployed in January 2010 as an addition to Michigan’s 

ambient air monitoring network for lead.4 

Population Data, Growth Rates, and Patterns 

Table 5 shows the 2008 population for each county in the area being evaluated, as well as the 

population density (people/square mile) for each county in that area. These data help assess the 

extent to which the concentration of human activities in the area and concentration of populationoriented 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.

County State 

Recommended 

Nonattainment?

2008 

Population

2008

Population 

Density 

(pop/sq mi)

Population 

Change 

2000-2008

Population % 

Change 

2000-2008

Ionia, Michigan Yes (partial) 63,833 110 2,156 3

Table 5: Population Data for Ionia County, Michigan

(U.S. Census Bureau estimates for 2008 and estimation of the area of U.S. Counties)

http://www.census.gov/popest/datasets.html

EPA has considered the population growth rate for this area and does not believe that it affects 

the boundary recommendation.

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 3 represent 

emissions levels taking into account any control strategies implemented on stationary sources in 

Belding before 2008. As part of its December 10, 2010 submittal, MDEQ included additional 

information on controls put into place since 2008.

Specifically, MDEQ’s submittal addresses emissions points and control measures for Mueller 

Industries, including: 2 chip dryers (west and east) and 3 induction furnaces (No. 7, No. 8, and 

No. 9). MDEQ informed EPA that the west chip dryer is a rotary kiln, and the only operational 

chip dryer as of August 9, 2010. This chip dryer is permitted under State new source review 

(NSR) permit number 505-93. Emissions from this dryer are controlled by a multi-clone unit, 

followed by a thermal oxidizer and pre-cooler/wet scrubber. In September 2010, Mueller 

Industries installed enhancements to the pre-cooler/wet scrubber to control system efficiency. 

These enhancements included the installation of a new spray nozzle system as well as the 

addition of a de-mister unit. The east chip dryer has not been operational since August 9, 2010, 

and is permitted under State NSR permit number 281-86A. Emissions at this unit are controlled 

by a multi-clone unit followed by a thermal oxidizer and pre-cooler/wet scrubber. Mueller 

Industries has agreed not to restart this unit unless compliance testing is conducted. 

 

4 Counties in Michigan with lead monitors deployed prior to January 2010 include: Wayne, Kent, Washtenaw, 

Genesee, and Missaukee. 
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Induction furnace No. 7 and No. 8 are permitted under State NSR permit number 30-83B, while 

No. 9 is permitted under State NSR permit number 30-83C. The emissions from these furnaces 

are controlled by fabric baghouses. 

Meteorology (weather/transport patterns)

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

other meteorological monitoring sites in the area. Historical wind direction frequencies are 

included in Figure 5 and Table 6. 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. MDEQ included a wind rose for Ionia County in their submittal, as well 

as a graphical representation of average lead concentrations correlated to wind direction. These 

are shown in Figure 6 and Figure 7, respectively. 

Figure 5: Historical Wind Direction Frequencies for Ionia County, Michigan

Figure 5 is a 3-dimensional bar chart that shows the wind frequencies in 8 directions for the 4 

seasons. These data are taken from 1960-1992 Solar and Meteorological Surface Observation 

Network information issued jointly by the U.S. Department of Commerce: National Climatic 

Data Center and the U.S. Department of Energy: National Renewable Energy Laboratory. The 

chart frequencies reflect the directions from which the winds come. 

Ionia County

Wind Frequencies

Frequency as a %

Seasonal Wind 

Directions

7.2 WINWINDFNNE
10

8.4 WINWINDFENE

7.8 WINWINDFESE

8 WINWINDFSSE

22.7 WINWINDFSSW

18.3 WINWINDFWSW

19.6 WINWINDFWNW

8 WINWINDFNNW

10.7 SPRWINDFNNE

12.4 SPRWINDFENE

11.8 SPRWINDFESE

8.9 SPRWINDFSSE

15.2 SPRWINDFSSW

14.9 SPRWINDFWSW

16.6 SPRWINDFWNW

9.4 SPRWINDFNNW

9.6 SUMWINDFNNE

9.5 SUMWINDFENE

8.3 SUMWINDFESE

9 SUMWINDFSSE

20.2 SUMWINDFSSW

19 SUMWINDFWSW

16 SUMWINDFWNW

8.4 SUMWINDFNNW

8.2 AUTWINDFNNE

7.7 AUTWINDFENE

9.1 AUTWINDFESE

11.5 AUTWINDFSSE

23.2 AUTWINDFSSW

16 AUTWINDFWSW

16.3 AUTWINDFWNW

8.1 AUTWINDFNNW

Table 6: Historical Wind Frequency Data as Percents for Ionia County, Michigan

As shown in Figure 5 and Table 6, the period with the least variability in wind is the winter 

months, with winds blowing from the south southwest. With the consistently strong 

representation of winds from a variation of the west in all seasons, special care must be made 

when determining the nonattainment boundary to the east of the violating monitor. 
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Figure 6: Wind Rose Data from Grand Rapids (MDEQ)

Figure 6, which represents wind frequencies collected at Grand Rapids between 2005 and 2009, 

corroborates the data already presented in Figure 5 and Table 6. 

Figure 7: Average Concentration of Lead by Wind Direction (MDEQ)
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MDEQ also provided Figure 7 in its December 2010 submittal. This graphical representation 

shows that when the wind is blowing from the west (or a variation thereof), the average 

concentration of lead is the highest. Again, this data indicates that special care must be made 

when determining the nonattainment boundary to the east of the violating monitor. 

Geography/topography (mountain ranges or other air basin boundaries)

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

effect on the air shed and, therefore, on the distribution of lead over Belding and the surrounding 

area. 

The Belding area does not have any geographical or topographical barriers significantly limiting 

air-pollution transport within its air shed. Therefore, this factor did not play a significant role in 

determining the nonattainment boundary.

Jurisdictional boundaries 

Existing jurisdictional boundaries may be helpful in articulating 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 EPA’s August 21, 2009 guidance memorandum, “Area Designations for the 2008 revised 

Lead National Ambient Air Quality Standard,” EPA reiterated that the presumptive boundary for 

each nonattainment area should be the county containing the violating monitor. This concept 

was first introduced in the guidance for the 1978 lead NAAQS designations, and is described in 

the 1992 General Preamble (57 FR 13549). This same presumptive boundary guidance was 

addressed most recently in the final rulemaking for the 2008 lead NAAQS (73 FR 66964). EPA 

observed, however, that States have the flexibility in their recommendations to deviate from the 

presumptive county boundary to portions of the county containing the violating monitor, stating 

that any “nonattainment area boundaries that deviate from presumptive county boundaries should 

be supported by an assessment of several factors...,” all of which have been discussed already in 

this document, except for jurisdictional boundaries.

For the Belding area, there are several jurisdictional boundaries that can be considered. Belding 

is located completely in Ionia County, which is part of the Grand Rapids-Wyoming Metropolitan 

Statistical Area. Ionia County is also part of a larger Grand Rapids-Muskegon-Holland 

Combined Statistical Area. The Grand Rapids Air Quality District Office is responsible for air 

quality planning within all areas of Ionia County. As a result, air quality planning efforts to 

address the impending lead nonattainment area in Belding should not be problematic; it should 

be noted that the final rulemaking for the 2008 lead NAAQS (73 FR 66964) specifically 

addressed transportation conformity by stating, “In light of the elimination of lead additives from 

gasoline, transportation conformity does not apply to the Lead NAAQS.” Lastly, MDEQ has 
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recommended that the boundaries for the Belding nonattainment area follow well-known streets 

and extensions of those streets. 

Other Relevant Information

EPA received additional relevant information from Michigan for establishing the nonattainment 

area boundary for Belding. This information will be discussed below.

MDEQ conducted air dispersion modeling (using AERMOD) of emissions to demonstrate that 

all predicted NAAQS exceedances fall within the recommended nonattainment boundary. In 

performing their AERMOD analysis, MDEQ took into account land use and terrain, building 

wake effect (effect on local air concentrations and particle deposition resulting from air flow 

around the buildings), and 2005 – 2009 Grand Rapids meteorological data.

Additionally, MDEQ used potential-to-emit (PTE) emissions of likely operations instead of the 

actual emissions from the NEI08V1.5; using PTE emissions in modeling inputs results in a much 

more conservative (larger) nonattainment area because PTE emissions represent the maximum 

allowable rate. The primary chip dryer (west) has a PTE rate of 0.3 pounds per hour, and the 

induction furnaces have an associated PTE rate of 5 micrograms per dry standard cubic foot. In 

its submittal, MDEQ observed that because the relatively short facility stacks are subject to 

building downwash, the maximum impacts were anticipated to be near the facility structure. The 

graphical result of MDEQ’s modeling analysis is below in Figure 8. 

Figure 8: Air Dispersion Modeling for Mueller Industries (MDEQ)
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The point of highest modeled impact (3.36 μg/m3) is northeast of the facility. This direction is 

consistent with the meteorological data collected at Grand Rapids. The monitor is represented 

by the blue star in Figure 8, and rests very close to the modeled 1.00 μg/m3isopleth. Referring 

to Table 3, the design value for this monitor between 2008 and 2010 was 0.28 μg/m3, or 28% of 

the modeled value. This result also supports the notion that the use of PTE emissions instead of 

actual emissions results in a more conservative (larger) nonattainment area. In other words, the 

modeling analysis performed by MDEQ over-predicts the lead concentrations in the Mueller 

Industries vicinity. 

Figure 9: Air Dispersion Modeling Analysis and State Recommended Nonattainment Area (MDEQ)

 

As seen above in Figure 9, the State recommended nonattainment area for Belding encompasses 

all likely effects of lead emissions from Mueller Industries equal to, or below, the 0.10 μg/m3

modeled ispoleth. As noted above, the modeling performed by MDEQ over-predicts lead 

concentrations in the area when compared to the monitored values; as a result, the area outside of 

the 0.10 μg/m3isopleth most likely experiences an impact of less than 0.10 μg/m3. 

EPA concludes that although the modeling performed by MDEQ may not meet the requirements 

for an attainment demonstration, the air dispersion modeling using PTE emissions performed for 

Ionia County in relationship to the entire State recommended nonattainment area is useful in 

determining a boundary for the nonattainment area.
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Conclusion

After considering the factors described above, EPA has determined that it is appropriate to 

designate a portion of Ionia County as nonattainment for the 2008 lead NAAQS.

The air quality monitor in Ionia County shows a violation of the 2008 lead NAAQS, based on 

2008-2010 air quality data. Mueller Industries is located in Belding, and is almost entirely 

responsible for all lead emissions in Ionia County. There are no other major sources of lead 

emissions in the State recommended nonattainment area, and the cumulative process of the

multi-factor analysis in conjunction with the relevant air dispersion modeling that MDEQ

provided ultimately leads to the final nonattainment area. 

EPA finds it appropriate to designate as nonattainment the portions of Ionia County that are 

encompassed by the coordinates listed below. 

Boundary Location Longitude Latitude

Southeast Corner -85.2130771 43.0956705

Southwest Corner

(Intersection of S. Broas St. 

and W. Washington St.) -85.2324027 43.0960358

Northeast Corner -85.2132313 43.1074942

Western Boundary 1

(Intersection of W. Ellis St. and the vertical 

extension of S. Broas St.) -85.2322553 43.1033277

Western Boundary 2

(Intersection of W. Ellis St. and N. Bridge St.) -85.2278464 43.1033911

Western Boundary 3

(Intersection of N. Bridge St. and Earle St.) -85.2279722 43.1074479

Table 7: Belding, Michigan Nonattainment Area Boundaries

Based on the consideration of all the relevant and 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 lead 

NAAQS. 
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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 3 years of quality assured air quality monitoring 

data from 2008-2010 including at least a singular valid 3-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 3 years of quality assured air quality monitoring data 

from 2008-2010 including 36 consecutive valid 3-month site means (including the last 2 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 3 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) Recommended nonattainment area – an area a State or Tribe has recommended to EPA be 

designated as nonattainment.

5) 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 3 months of data are necessary to

produce a valid violating design value. 

6) 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.

7) 2008 lead NAAQS – 0.15 μg/m3, National Ambient Air Quality Standard for lead 

promulgated in 2008. Based on Pb-TSP indicator and a 3-month rolling average. Pb-PM10 data

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