TECHNICAL SUPPORT DOCUMENT

Montana Initial Designations

2012 Revised Annual PM 2.5 National Ambient Air Quality Standards

I. EXECUTIVE SUMMARY

On December 14, 2012 , EPA revised the national ambient air quality standards (NAAQS) for

Particulate Matter smaller than 2.5 microns ( PM 2.5 ), revising the annual prima ry (health

based) standard from 15 micrograms per cubic meter ( μg/m 3 ) to 12 μg/m 3 expressed as the

3

- year average of the annual mean concentrations. The primary 24

- hour PM 2.5 NAAQS has

been retained and not revised ; therefore, Montana’s initial statewide designations address only the revised annual PM 2.5 NAAQS. The revision was publis hed in the Federal Register (FR) on January 15, 2013 at 78 FR 3086

.

According to 42 USC §7407, et seq

., Montana must submit to EPA an initial list of geographic areas that attain the standard or that do not attain the standard or that are

otherwise unclassifiable based on available information. Montana herby designates all areas (Counties) within the state as “ attainme nt ” or “ unclassifiable ” for the 2012 revised primary annual PM 2.5 NAAQS. The following evaluation substantiates Montana’s area designations.

Designations for Counties

Based on available information, Montana determined that an init ial designation of

“a ttainment” is appropriate for 6 Montana counties with active PM 2.5 State or Local Air Monitoring Stations (SLAMS ) located within their respective boundaries for the design value period of 2010 through 2012

. A vailable monitoring data collected at the SLAMS supports a
conclusion that ambi ent concentrations of PM 2.5 in those counties is in compliance and

therefore attains the 2012 revised annual PM 2.5 NAAQS

.

Those countie s to be designated “a ttainment” include : Silver

- Bow

, Missoula, Lewis and Clark, Lincoln, Powder River and Ravalli.

The remaining 50 counties in Montana should be designated as “a ttainment ” or

“ u nclassifiable ” due to a lack of appropriate and/or adequate monitoring data to determine NAAQS compliance

.

1II. MONITORING DATA

Statewide, Montana operates 13 SLAMS and 5 Special Purpose Monitors (SPM). Figure 1

below shows the location of all PM 2.5 monitors in the state. State or Local Air Monitoring

Stations use only Federal Reference Methods (FRM) or Federal E quivalent Methods (FEM)

and therefore provide data suitable for NAAQS compliance comparisons

. Special Purpose Monitors do not necessarily use FRM or FEM monitoring methods and are primarily used for research purposes and therefore produce non

- regulatory data unsuitable for NAAQS compliance comparisons

.

Figure 1, Location of all PM2.5 Monitors within Montana

Table 1 below provides monitoring site designation s (SLAMS, SPM) and monitor location s within their respective c ounty f or all PM 2.5 monitors within the state. Table 1 includes

SLAMS meeting data completeness requirements for the design value period of 2010

- 2012

, SLAMS not meeting data completeness requirements for the design value period of 2010

- 2012 and SPMs

.

2Table 1, Montana’s PM 2.5 Monitoring Network

Montana is regularly impacted by smoke from wildfires both within and outside of the state. When ambient air monitoring data is impacted by wildfires, states flag these data as “exceptional events” thereby remo ving the subject data from consideration in design value

calculations to be used for NAAQS compliance comparisons. Flagged data may be excluded from the design value calculation assuming the event is “ not reasonably controllable or preventable, is an even t caused by human activity that is unlikely to recur at a particular location or a natural event, and is determined by the EPA in accordance with 40 CFR 50.14 to be an exceptional event. ” In some cases, t he data represented in this

document

, and used to calculate design values

, includes “exceptional events” that have been flagged as wildfire impacted data.

Figure 2 below shows the calculated design values for all 18 monitors in the state for the design value period of 2010

- 2012 , excluding only flagged SLAMS data with EPA

concurrence

. Site Location Site Location Site Location

30-063-0024 Missoula-Boyd Park (Missoula Co.) 30-029-0049 Flathead Valley (Flathead Co.)* 30-063-0038 Seeley Lake (Missoula Co.) (SPM)

30-063-0037 Frenchtown (Missoula Co.) 30-083-0001 Sidney (Richland Co.)* 30-111-0085 Billings (Yellowstone Co.) (SPM)

30-093-0005 Butte (Silver-bow Co.) 30-049-0004 Sieben's Flat (Ncore) (Lewis & Clark Co.)* 30-031-0019 Bozeman (Gallatin Co.) (SPM)

30-081-0007 Hamilton (Ravali Co.) 30-071-0010 Malta (Phillips Co.)* 30-013-0001 Great Falls (Cascade Co.) (SPM)

30-053-0018 Libby (Lincoln Co.) 30-087-0001 Birney (Rosebud Co.)* 30-031-0017 W. Yellowstone (Gallatin Co.) (SPM)

30-075-0001 Broadus (Powder River Co.) 30-027-0006 Lewistown (Fergus Co.)*

30-049-0026 Helena (Lewis and Clark Co.) State & Local Air Monitoring Stations Montana PM2.5 Monitoring Network

State Special Purpose Monitors (SPM)

Meeting Data Completeness Requirments Not Meeting Data Completeness Requirments Data not flagged for Exceptional Events

3Figure 2, Annual PM 2.5 3

- Year Average of A nnual M ean at All M onitors

Based on the values represented in Figure 2 above, it should be noted that DEQ operates a

non

- FEM SPM at Seeley Lake Elementary School. This SPM was initially sited, installed and operated as part of Montana’s “Today’s Air” PM 2.5 network which is designed to provide

the citizens of Montana with near

- real

- time PM 2.5 concentrations in geographically strategic

locations state

- wide. In response to the high PM 2.5 values monitored at this SPM site the state of Montana, in cooperation w ith the Missoula City

- County Health Department (MCCHD), conducted a wintertime study of the area using E

- BAMs to determine the

geog raphic extent of the problem. Based on the results of this study it has been determined

that PM 2.5 concentrations measured a t the Seeley Lake Elementary School SPM site are representative of neighborhood scale impacts, and not the overall Seeley Lake airshed.

In response to this neighborhood scale issue, the MCCHD has initiated an episodic control program (PM 2.5 Alerts) as we ll as a substantial and on

- going subsidized process to replace aging and inefficient wood

- burning devices in the Seeley Lake area. The effectiveness of this ongoing effort will continue to be monitored at the Seeley Lake Elementary School SPM

site.

Fig ure 3 below removes all non

- regulatory data obtained from SPMs and shows data from

all SLAMS in the state. All data from SLAMS monitors shown in Figure 3 demonstrate s compliance with the 2012 revised annual PM 2.5 NAAQS

. However, as discussed previously, several of Montana’s SLAMS did not meet data completeness requirements for the design value period of 2010

- 2012. Due to a lack of data completeness for the design value period

of 2010

- 2012, these SLAMS should not be us ed to designate the areas as attainment; however, they do support a designation of unclassifiable.

4Figure 3, Annual PM 2.5 Design Values for A ll SLAMS

Figure 4 below removes all data from SLAMS which did not meet data completeness requirements during one or more years during the design value period of 2010

- 2012

. T he data shown in Figure 4 demonstrates compliance with the 2012 revised annual PM 2.5 NAAQS

.

5Figure 4, Annual PM 2.5 Design Values for All SLAMS Meeting Data Completene ss
R equirements

Figure 5 below represents the available complete SLAMS ambient monitoring data set for the design value period of 2010

- 2012 excluding all flagg ed data . As shown in the figure all SLAMS meeting data completeness requirements for the 2010

- 2012 design value period demonstrate compliance with the 2012 revised annual PM 2.5 NAAQS of 12 ug/m 3

.

6Figure 5

– Annual PM 2.5 Design Values Excluding Flagged Data

Montana has appropriately flagged all monitoring data impacted by qualifying “ exceptional

events ” through calendar year 2012. H owever , Montana only recently submitted a demonstration package providing justification for calendar year 2010 flagged data and t o date has not submitted a demonstration for flagged data in calendar years 2011 and 2012. Therefore, EPA has not had an opportunity to concur with all of the affected data for the design value period of 2010

- 2012

.

Figure 6 below represents a compari son of the data presented in Figure 5 (design values excluding all flagged events) with data including all exceptional events without EPA

concurrence . Figure 6 demonstrates that inclusion of all flagged data (non

- concurred)

increases design values but not to a level exceeding the 2012 revised annual PM 2.5 NAAQS

.

7Figure 6

– Annual PM 2.5 Design Value comparison with and without flagged data.

III. Conclusion

According to 42 USC §7407, Montana is required to submit to EPA a list of all areas (or portions thereof) in the state, designating as “nonattainment”, “attainment”, or otherwise

“u nclassifiable” based on available information. Through implementation of a robust PM 2.5 ambient air quality monitoring network the state of Montana has presen ted a strong case supporting the initial designations listed below.

Based on available information , as presented throughout this document , Montana determined that an initial designation of “ a ttainment” is appropriate for the following

counties : Silver

- Bow, Missoula, Lewis and Clark, Lincoln, Powder River and Ravalli. The remaining 50 Montana counties should initially be designated as “attainment” or

“u nclassifiable” for the 2012 revised annual PM 2.5 NAAQS.

8