Justification for Discontinuation of Monitoring in Carbon 

Monoxide and PM10 Maintenance Areas

Submitted to: Keith Rose, EPA Region 10

By: Anthony Barnack, Oregon DEQ

October, 2011

Last Updated: 12/01/11

By: Anthony Barnack

Report
This report prepared by:

Oregon Department of Environmental Quality

811 SW 6th Avenue

Portland, OR 97204

1-800-452-4011

www.oregon.gov/deq

Contact:

Anthony Barnack

(503) 229-5713
Monitoring Discontinuation Justification 3 3

Table of Contents

1. Executive Summary .....................................................................................................................1

2. Introduction..................................................................................................................................2

3. Pollutant Trends and Source of Emissions ..................................................................................2

3.1 Carbon Monoxide Trends for Eugene/Springfield and Medford ........................................................................2

3.2 Carbon Monoxide Emission Sources in Eugene/Springfield and Medford ........................................................4

3.3 PM10 Trends........................................................................................................................................................4

3.4 PM10 Emission Sources in Eugene/Springfield and Medford.............................................................................5

4. Fraction of PM10 that is PM2.5......................................................................................................5

4.1 Klamath Falls PM10 vs. PM2.5 ............................................................................................................................6

4.2 Grants Pass PM10 vs. PM2.5:...............................................................................................................................7

4.3 PM10 vs. PM2.5 Summary: ..................................................................................................................................9

5. Emission Estimate Methods: .......................................................................................................9

5.1 The Central Lane MPO Regional Emissions Analysis .......................................................................................9

5.2 The Rogue Valley Regional Emissions Analysis..............................................................................................10

6. An alternate approach for tracking the pollutant .......................................................................10

6.1 Tracking Carbon Monoxide:............................................................................................................................10

6.2 Tracking PM10: ................................................................................................................................................11

7. Alternate contingency measure trigger......................................................................................11

7.1 Alternative trigger for CO for Medford UGB:.................................................................................................11

7.2 Alternative trigger for CO for Eugene/Springfield AQMA: ............................................................................12

7.3 Alternative trigger for Klamath Falls PM10 Urban Growth Boundary.............................................................13

7.4 Alternative trigger for Grants Pass PM10 Urban Growth Boundary.................................................................14

8. Conclusion .................................................................................................................................14

9. Reference ...................................................................................................................................15

Table of Figures

Figure 1. Medford and Eugene/Springfield CO trends.................................................................. 3

Figure 2. Grants Pass and Klamath Falls PM10 trends................................................................... 4

Figure 3. Klamath Falls, Peterson School PM10/PM2.5 Correlation............................................... 6

Figure 4. Klamath Falls winter time PM10 distribution of PMcoarse and PM2.5. .......................... 7

Figure 5. Grants Pass, Parkside School PM10/PM2.5 Correlation................................................ 8

Figure 6. Grants Pass, winter time PM10 distribution of PMcoarse and PM2.5.............................. 8

Table of Tables

Table 1. Medford and Eugene/Springfield CO design values. ...................................................... 3

Table 2. Medford and Eugene/Springfield PM10 design values. ................................................... 5

Table 3. PM2.5 fraction of PM10 Average and 95% confidence level. ........................................... 9

Table 4. 2010 CO emission estimates within the Eugene/Springfield boundary. ....................... 10

Table 5. 2010 CO emission estimates within the Medford urban growth boundary. .................. 10

Table 6. Linear regression equations and ratios used to estimate PM10 using PM2.5................... 14
Glossary of Terms:

NAAQS – National Ambient Air Quality Standards (EPA criteria pollutant standards)

CO – Carbon monoxide

PM10 – Particulate matter, 10 microns in diameter or smaller

PM2.5 - Particulate matter, 10 microns in diameter or smaller

ODEQ – Oregon Department of Environmental Quality

LRAPA – Lane Regional Air Protection Authority (Lane County, Oregon)

SIP – State Implementation Plan 

ppm – Parts per million (concentration)

μg/m3– micrograms per meter cubed (concentration)

FRM – Federal Reference Method

MPO – Metropolitan Planning Organization

AQCD - The Air Quality Conformity Determination
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1. Executive Summary

Due to budget cuts, Oregon DEQ and the Lane Regional Air Protection Authority needed to 

discontinue carbon monoxide and PM10 monitoring in maintenance areas which are now far 

below the National Ambient Air Quality Standard (NAAQS). The monitoring funds have 

either been lost or reinvested in higher priority monitoring such as PM2.5 or ozone. These 

pollutants are much closer to the NAAQS and require sustained monitoring.

The CO and PM10 maintenance plans require continued monitoring for compliance 

determination and as triggers for contingency plans. To remove this requirement from the 

plans would require resources and time that ODEQ and LRAPA cannot afford at this time. 

EPA Region 10 has proposed a compromise which would require the use of alternative 

methods to track these pollutants in maintenance areas. The alternative methods will be 

included in the next maintenance plan revisions. 

The method for tracking CO would use the regional emissions analysis performed in the Air 

Quality Transportation Conformity Determination. This is conducted every four years by the 

Metropolitan Planning Organizations. These analyses will show the emission trends and will 

provide a trigger for the contingency plans written into the maintenance plans. As a real time 

measure, the Portland CO monitor will be used to track trends in general CO levels.

For PM10, PM2.5 will be used as a surrogate. The percent of PM10 that is PM2.5 is very high in 

Oregon and the control strategies are the same for both pollutants. 

Maintenance Plans are located at: http://www.deq.state.or.us/aq/planning/maintenance.htm
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2. Introduction

Beginning in the 1970s, and continuing through the early part of the 1990s, Oregon had 

several communities that violated the carbon monoxide and PM10 NAAQS and were 

consequently declared out of attainment for these pollutants. Oregon DEQ and local stake 

holders implemented State Implementation Plans (SIPs) to bring these areas under the 

NAAQS. After many years of levels below the standards, maintenance plans were installed 

to keep the air quality below the NAAQS. The maintenance plans included requirements to 

continue monitoring to determine long-term trends and compliance. Monitoring was also 

required for contingency measure triggers for additional regulatory actions.

Over the last twenty years, the CO and PM10 concentrations have dropped far below the 

NAAQS. Monitoring continued only to meet the maintenance requirements, but had no real 

benefit for public health. The maintenance plans require monitoring until 2014 for 

Eugene/Springfield CO, and 2022 for Medford CO, and 2023 for Grants Pass PM10 and 

Klamath Falls PM10. Public health benefits most from PM2.5, ozone, and air toxic 

monitoring. 

In the last ten years ODEQ and LRAPA have experienced repeated budget cuts as a result of 

diminished revenue and expanded costs. In 2010 and 2011, budget cuts were especially deep 

and resulted in the elimination or reprioritization of many monitoring activities. ODEQ and 

LRAPA had already cut discretionary monitoring and had to now consider shutting down 

required, but low priority monitoring. CO and PM10 sites were considered expendable as 

long as alternative methods were available to track general concentrations and act as 

contingency measure triggers.

This report shows the how alternative methods can be used to adequately track CO and PM10

and trigger contingency measures.

3. Pollutant Trends and Source of Emissions

3.1 Carbon Monoxide Trends for Eugene/Springfield and Medford

The carbon monoxide levels have continuously dropped over the past 20 years and are now

routinely one quarter of the NAAQS. Figure 1 shows the CO trends for Medford and 

Eugene/Springfield and Table 1 provides the design values from 2000 to 2010. Medford has 

been below the NAAQS since 1993 and Eugene/Springfield has been below the NAAQS 

since 1983. With ever more cleaner cars on the road, the design values are not expected to 

increase.
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Figure 1. Medford and Eugene/Springfield CO trends.

Second highest 8 hour average.

Table 1. Medford and Eugene/Springfield CO design values.

Eugene Medford

(ppm)

% of 

NAAQS (ppm)

% of 

NAAQS

2000 4.3 45% 4.7 49%

2001 4.1 43% 4.6 48%

2002 4.2 44% 5.5 58%

2003 3.4 36% 4.7 49%

2004 3.4 36% 4 42%

2005 2.6 27% 3.8 40%

2006 2 21% 2.8 29%

2007 2.1 22% 2.7 28%

2008 1.7 18% 2.4 25%

2009 1.7 18% 2.4 25%

2010 1.3 14% ND ND

Based on annual 2nd highest, daily maximum eight hour average.

0

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20

1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

CO (ppm)

Medford and Eugene/Springfield Carbon Monoxide Trends

Medford

Eugene

NAAQS 8hr Average

Second highest 8hr average
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3.2 Carbon Monoxide Emission Sources in Eugene/Springfield and Medford

In the past, CO emissions in Medford and Eugene/Springfield were primarily from mobile 

source. In newer vehicles, catalytic converters, fuel injections, and electronic timing have 

greatly reduced tailpipe CO levels. As the vehicle fleet becomes newer the CO levels are 

expected to continue dropping. 

Non-mobile CO sources include industrial and area sources. Both areas have EPA Title V 

sources with Plant Site Emission Limits over 100 tons per year. These sources have been 

operating for years and are regulated. They would have to go through Prevention of 

Significant Deterioration review if they wanted to raise their CO emissions. 

Both areas also have a significant population using residential wood heating. Both were 

PM10 non-attainment areas and have had programs in place for years that encourages the use 

of certified woodstoves. All of Oregon now has the Heat Smart Program which requires the 

removal of non-certified woodstove upon sale of a home. Certified wood stoves emit far less 

CO than non-certified stoves. 

 

3.3 PM10 Trends 

Over the last 20 years PM10 levels have dropped statewide because of permitting programs 

and other reduction strategies. Figure 2 shows the PM10 trends for Grants Pass and Klamath 

Falls from 1987 to 2010. Table 2 provides the design values from 2000 to 2010. Grants Pass 

has been below the NAAQS since 1988 and Klamath Falls has been below the NAAQS since 

1991. 

Figure 2. Grants Pass and Klamath Falls PM10 trends.

0

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1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 μg/m3

PM10 for Klamath Falls and Grants Pass 

1987 to 2010

Grants Pass

Klamath Falls

NAAQS

2nd highest 24hr average PM10 value
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Second highest 24 hour average PM10 values.

Table 2. Grants Pass and Klamath Falls PM10 design values.

Grants Pass Klamath Falls 

(μg/m3)

% of 

NAAQS (μg/m3)

% of 

NAAQS

2000 40.0 27% 93.0 62%

2001 50.0 33% 62.0 41%

2002 41.0 27% 121.0* 81%

2003 49.0 33% 63.2 42%

2004 32.3 22% 70.4 47%

2005 37.5 25% 75.5 50%

2006 37.7 25% 56.3 38%

2007 39.3 26% 71.8 48%

2008 42.3 28% 71.7 48%

2009 ND ND 61.8 41%

2010 ND ND 40.8 27%

Based on annual 2nd highest, 24 hour average.

* The 2002 Klamath Falls PM10 value was from a forest fire but was not considered an 

exceptional event because it was below the NAAQS.

3.4 PM10 Emission Sources in Eugene/Springfield and Medford

In the past, PM10 emissions in Medford and Eugene/Springfield were primarily from 

industrial and area sources. Both areas have EPA Title V sources with Plant Site Emission 

Limits over 100 tons per year. Industrial sources were regulated and now have cyclones , 

bag houses, and more efficient boilers to control emissions. Other methods such as Wigwam 

burners were outlawed. If these sources wanted to emit more PM10 they would have to go 

through Prevention of Significant Deteriation review. 

The primary source of PM10 is now smoke from residential wood heating. Medford and 

Eugene/Springfield were PM10 non-attainment areas and have had programs in place for 

years that encourage the use of certified woodstoves. All of Oregon now has the Heat Smart 

Program which requires the removal of non-certified woodstove upon sale of a home. 

Certified wood stoves emit far less PM10 than non-certified stoves. 

4. Fraction of PM10 that is PM2.5

In Oregon, PM10 is mostly made up of PM2.5. This section will show the results of years of 

wintertime collocated PM10 and PM2.5 sampling in Klamath Falls and Grants Pass to 

ascertain the PM coarse (PMc) fraction of PM10. In Oregon, winter weather occurs from 

November through February. This is when most winter inversions occur and the highest 

concentrations are measured.
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4.1 Klamath Falls PM10 vs. PM2.5

Comparable PM10 and PM2.5 FRM samplers were operated in Klamath Falls from 2007 

through 2010. Comparison of the winter PM2.5 and PM10 data shows a correlation with an R 

Squared of 0.87 (Figure 3). During this period there were 17 samples greater than 1⁄4 of the 

NAAQS, three of which were greater than 1⁄2 the NAAQS. The highest value in the past 

three winters was 57% of the PM10 NAAQS. On average, winter PM10 is 70% PM2.5 by 

weight with a 95% confidence level of 66% to 74% (summarized in Table 3). Figure 4 

shows the PM2.5 and PMcoarse fractions for the highest winter values for 2007-2009.

Figure 3. Klamath Falls, Peterson School PM10/PM2.5 Correlation.

y = 1.4x + 1.0

R2 = 0.87

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0 10 20 30 40 50 60 70 80 90 100 PM10 ug/m3

PM2.5 ug/m3

Klamath Falls Winter PM2.5 and PM10 Comparison
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Figure 4. Klamath Falls winter time PM10 distribution of PMcoarse and PM2.5. 

Note: In Figure 4, PMc(red)+PM2.5 (blue) = PM10

Over the past ten years there were two years with elevated days outside of winter. In 2002, 

massive forest fires caused elevated levels during August; the PM10 was mostly PM2.5. In 

2009, a dust event caused an elevated level in early October. The dust event had a low PM2.5

quotient but the PM10 concentration (87μg/m3) was well below the NAAQS. If that single 

dust event was included in the linear regression done in Figure 2, the RSquared would 

change from 0.87 to 0.76 and the equation would change from y =1.4x+1.0 to y =1.4x+3.2. 

This is only a 2.2μg/m3higher PM10 derived value if the dust event is included. 

4.2 Grants Pass PM10 vs. PM2.5:

Comparable PM10 and PM2.5 samplers were co-located in Grants Pass from 2006 through 

2008. The PM2.5 and PM10 correlation has an R Squared of 0.94 (Figure 5).

From 2006 to 2008 there were only four samples over 1⁄4 of the NAAQS, and none over 1⁄2 the 

NAAQS. On average, winter PM10 is 73% PM2.5 by weight with a 95% confidence level of 

70% to 76% (summarized in Table 3). The highest value in the past three winters was only 

29% of the PM10 NAAQS. Figure 6 shows the PM2.5 and PM coarse fractions for the winter 

values for 2006-2008. 

-100%

-80%

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100%

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1 5 5 μg/m3

Klamath Falls Winter PM10, PM2.5, & PMc

Note: PM2.5 + PMc = PM10

PM10 = PM2.5 + PMc

% of PM10 that made up of PM2.5

y = 0.002x+0.6

Winter PM1 0 (PM2.5 + PMc) values from highest to lowest concentrations.
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Figure 5. Grants Pass, Parkside School PM10/PM2.5 Correlation.

Figure 6. Grants Pass, winter time PM10 distribution of PMcoarse and PM2.5. 

Note: In Figure 6, PMc(red)+PM2.5 (blue) = PM10

y = 1.2x + 2.6

R2 = 0.94

0

5

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15

20

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30

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40

45

50

0 10 20 30 40 50 PM10 μg/m3

PM2.5 μg/m3

Grants Pass winter PM2.5 and PM10 Comparison

-100%

-80%

-60%

-40%

-20%

0%

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100%

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1 ug/m3

Grants Pass Winter PM10, PM2.5, & PMc

Note: PM2.5 + PMc = PM10

PM10 = PM2.5 + PMc

% of PM10 that made up of PM2.5

y = -0.002x+0.8

Winter PM1 0 (PM2.5 + PMc) values from highest to lowest concentrations.
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4.3 PM10 vs. PM2.5 Summary:

Table 3 shows the summary of the winter co-located PM10 and PM2.5 samples. This 

percentage shows the percentage (by weight) of PM10 that is PM2.5. 

Table 3. PM2.5 fraction of PM10 Average and 95% confidence level.

Average 95% Confidence Level

Klamath Falls 70% 66% - 74%

Grants Pass 73% 70% - 76%

5. Emission Estimate Methods:

Modeled CO emission estimates are developed by the Metropolitan Planning Organizations 

(MPOs) for Eugene/Springfield and Medford as part of the transportation conformity 

requirements in the maintenance plans in accordance with Clean Air Act section 176(c).

Transportation conformity ensures that federal funding and approval are given to highway 

and transit projects that are consistent with ("conform to") the air quality goals established by 

a SIP. Conformity, to the purpose of the SIP, means that transportation activities will not 

cause new air quality violations, worsen existing violations, or delay timely attainment of the 

NAAQS.

A regional emissions analysis is a major component of demonstrating transportation 

conformity. The regional emissions analysis includes emissions from all current and planned 

regionally significant projects in the entire transportation system in the maintenance area for 

the duration of the transportation plan or TIP. The regional emissions analysis must use the

latest planning assumptions and latest emissions model.

This following section discusses the regional emissions analyses conducted in 

Eugene/Springfield and Medford for transportation conformity determinations.

5.1 The Central Lane MPO Regional Emissions Analysis

The Central Lane MPO is the agency responsible for performing the regional emissions 

analysis in the Eugene/Springfield maintenance area. The most recent regional emissions 

analysis was completed in 2010 for the “FY10-13 Metropolitan Transportation Improvement 

Program.”

The 2010 CO emissions projections from the regional emissions analyses are shown in Table 

4 (in tons per year). The first year listed, 2004, is the regional land use/transportation model

base year. 
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Table 4. 2010 CO emission estimates within the Eugene/Springfield boundary.

Analysis Year

Estimated CO Emissions 

(tons/yr)

2004 2,198

2008 1,634

2018 1,160

2028 1,056

2031 1,059

5.2 The Rogue Valley Regional Emissions Analysis

The Rogue Valley MPO is the agency responsible for performing the regional emissions 

analysis in the Medford maintenance area. The most recent regional emissions analysis was 

completed in 2010 “2010-2013 Metropolitan Transportation Improvement Program 2009-

2034 Regional Transportation Plan”. 

The 2010 AQCD’s CO emissions from the regional emissions analysis are shown in Table 5

(in pounds per day). The first year listed, 2005, is the regional land use/transportation 

model base year used in the “2001-2023 Regional Transportation Plan and 2002-2005 

Transportation Improvement Program”.

Table 5. 2010 CO emission estimates within the Medford urban growth boundary.

Analysis Year

Estimated CO Emissions 

(lbs/day)

2005 33,910 

2015 19,359

2020 20,280

2026 19,770

2034 32,640

6. An alternate approach for tracking the pollutant

CO and PM10 maintenance plans required continued monitoring to determine NAAQS 

compliance. If the monitoring agency discontinues monitoring, CO and PM10 must be 

tracked using alternative methods. This section outlines the specific tracking methods 

ODEQ and LRAPA will use for CO in Medford and Eugene/Springfield, and PM10 in 

Klamath Falls and Grants Pass.

6.1 Tracking Carbon Monoxide:

Carbon monoxide has traditionally been tracked by monitoring and modeling. Once

monitoring is discontinued in the Eugene/Springfield and Medford maintenance areas, 

regional emissions modeling will be the primary method of tracking CO. 
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Because on-road motor vehicle emissions are the primary source of CO in the 

Eugene/Springfield and Medford maintenance areas, ODEQ believes the regional emissions 

analysis conducted for the CO maintenance areas provides an effective surrogate method for 

tracking CO emissions. The regional emissions analysis must use the latest planning 

assumptions (e.g., population, vehicle miles traveled, employment estimates) and the latest 

emissions model. The regional emissions modeling is done at least every four years and 

produces CO estimates based on current and planned transportation activities throughout the 

CO maintenance areas. If these estimates exceed the base year estimates (shown in italics in 

Tables 4 and 5), then the current CO concentrations may be higher than the design values for 

those years (3.4 ppm in Eugene in 2004 and 3.8 ppm in Medford in 2005, see Table 1). If 

this occurs, EPA and ODEQ or LRAPA will decide whether to conduct CO survey 

monitoring. If the CO survey monitoring shows levels > 1⁄2 of the NAAQS, then CO 

monitoring will be restarted. Survey monitoring is done with an inexpensive non-FRM 

monitor.

ODEQ will also continue to monitor CO in Portland. This monitoring will track general CO 

concentrations, because if the CO levels increase in Portland, they may also be going up in 

the other cities. If the Portland CO design value exceeds 1⁄2 the NAAQS, survey monitoring 

may be performed at the former Medford and Eugene/Springfield CO sites to determine 

current conditions. If the surveyed CO levels are 1⁄2 the NAAQS, CO monitoring will be 

restarted.

The CO estimates will be included in the annual network review. 

6.2 Tracking PM10:

PM10 in Klamath Falls and Grants Pass will be tracked using PM2.5 monitoring. The major 

source of PM10 in these communities is smoke from wood heating. The percentage of PM10

which is PM2.5 is known in both of these communities and PM10 estimates can be made using 

PM2.5 monitored levels. PM2.5 is monitored with both continuous and FRM samplers. Table 

6 contains the linear regression equations used to estimate PM10 from PM2.5 at these sampling 

locations. 

The PM10 estimates will be included in the annual network review. 

7. Alternate contingency measure trigger

CO and PM10 maintenance plans contain contingency triggers which are tied to monitored 

levels. If the trigger concentration is reached, ODEQ or LRAPA must institute the 

contingency measures outlined in the maintenance plan. If the monitoring agency wants to 

discontinue monitoring, they need to offer an alternative method to measure air quality for 

comparison to the trigger level. This section outlines the specific alternative trigger methods 

for CO in Medford and Eugene/Springfield, and PM10 in Klamath Falls and Grants Pass.

7.1 Alternative trigger for CO for Medford UGB:

Contingency trigger requirements:

On March 9th, 2001, the Environmental Quality Commission adopted the State 

implementation plan revision for carbon monoxide in the Medford urban growth boundary (a 
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plan for maintaining the national ambient air quality standards for carbon monoxide). 

Section 4.52.3.3 of the plan requires a “Contingency Plan” to take effect if the second highest 

daily 8 hour average monitored values were 1) above 90% of the NAAQS (phase 1), or 2) 

above the NAAQS (phase 2). The “Plan” makes an exception for the Medford Old Car 

Rally. 

The problem:

ODEQ had to discontinue CO monitoring due to budget cuts and very low concentrations. 

The contingency plan relies on continued monitoring to compare to the trigger points. 

ODEQ needs to adopt a trigger point based on an alternative pollutant measure.

The Solution:

For Medford, two alternative contingency trigger methods will be used. Method 1 relies on 

estimates produced every four years. Method 2 relies on hourly, real time data. 

Method 1:

The first method will be to use the modeled CO emissions in the regional emissions analysis

conducted every four years by the Rogue Valley MPO for the transportation conformity 

determination. If the modeled emissions are above the modeled baseline year emissions, CO 

survey monitoring will be started to determine whether the contingency requirements are 

triggered. Survey monitoring is done with an inexpensive non-FRM monitor.

Method 2:

The Portland, SE Lafayette CO monitor will be used as a surrogate. This provides real time 

monitoring data. If the Portland monitor reaches 1⁄2 the NAAQS, survey sampling will be 

started in Medford to determine whether the contingency requirements are triggered. Survey 

monitoring is done with an inexpensive non-FRM monitor.

7.2 Alternative trigger for CO for Eugene/Springfield AQMA:

Contingency trigger requirements:

On February 27th, 1992, Lane Regional Air Pollution (now Protection) Authority sent an 

addendum to their carbon monoxide maintenance plan title “Contingency Commitment for 

Amendment of Oregon’s SIP, Eugene-Springfield carbon monoxide Attainment 

Redesignation & Adoption of Maintenance Plan”. The letter committed LRAPA to a carbon 

monoxide contingency plan as part of their carbon monoxide maintenance plan. The letter 

stated that “Within 60 days of reporting on AIRS that a violation of the carbon monoxide

NAAQS has occurred within the Eugene-Springfield AQMA, LRAPA and LCOG will 

submit to the EPA a contingency plan for attaining the standard, which will be implemented 

as expeditiously as practicable”. Since the carbon monoxide NAAQS was never violated 

following this letter, the contingency plan for attaining the standard was never required.

The problem:

LRAPA had to discontinue CO monitoring due to budget cuts and low CO concentrations. 

The contingency plan relies on continued monitoring to compare to the trigger points. 

LRAPA needs to adopt a trigger point based on an alternative pollutant measure.
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The Solution:

For Eugene/Springfield, one of two alternative contingency trigger methods will be used. 

Method 1 relies on estimates produced every four years. Method 2 relies on hourly, real time 

data. 

Method 1:

The first method will be to use the modeled CO emissions in the regional emissions analysis 

conducted every four years by the Central Lane MPO. If the modeled emissions are above 

the modeled baseline year emissions, CO survey monitoring will be started to determine 

whether the contingency requirements are triggered. Survey monitoring is done with an 

inexpensive non-FRM monitor.

Method 2:

The Portland, SE Lafayette CO monitor will be used as a surrogate. This provides real time 

monitoring data. If the Portland monitor reaches 1⁄2 the NAAQS, survey sampling will be 

started in Eugene to determine whether the contingency requirements are triggered. Survey 

monitoring is done with an inexpensive non-FRM monitor.

7.3 Alternative trigger for Klamath Falls PM10 Urban Growth Boundary

Contingency trigger requirements:

In October 2002, the Klamath Falls PM10 maintenance plan was finalized, installing a 

contingency plan that said:

Phase 1: Risk of Violation

The County and DEQ will reconvene a planning group to develop an action plan if 

ambient concentrations (actual or estimated) equal or exceed 90% of the NAAQS 

concentration of PM10 (135μg/m3 for the 24 hour average or 45μg/m3 for an annual 

average) at Peterson School. The planning group will prepare an action plan that 

includes a schedule for implementation of additional strategies as necessary to prevent an 

exceedance or violation of PM10 standards. If the high PM10 concentration was 

determined to be a natural event based on EPA's policy or an exceptional event, no 

further action may be needed.

Phase 2: Actual Violation 

If a violation of the PM10 standard occurs and is validated by DEQ, the following 

contingency measures will automatically be implemented:

The problem:

DEQ had to discontinue PM10 monitoring due to budget cuts and low PM10 levels. The 

contingency plan relies on continued PM10 monitoring to compare to the trigger points. 

ODEQ needs to adopt a trigger point based on an alternative pollutant measure.

The Solution:

The PM10 alternative pollutant measure will be to use PM2.5 monitoring as a surrogate. The 

PM2.5 relationship to PM10 has been established in recent years with collocated PM10 and 

PM2.5 monitors. Linear regression analysis was performed on the PM10 and PM2.5 data 
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(Figure 3) and a linear regression equation was established (Table 6). Using this linear 

regression equation, ODEQ has determined the PM2.5 concentration needed to trigger the 

PM10 “Risk of Violation” and “Actual Violation” levels discussed above, also shown in 

Table 6.

7.4 Alternative trigger for Grants Pass PM10 Urban Growth Boundary

Contingency trigger requirements:

In October 2002, the Grants Pass PM10 maintenance plan was finalized, installing a 

contingency plan that said: 

“DEQ will convene a planning group if the 24-hour PM10 concentration as measured at 

the Grants Pass PM10 monitor equals or exceeds 120μg/m3. The planning group will 

assess the probable emissions event resulting in the elevated PM10 level and consider a 

range of measures with the potential to reduce emissions. However, if a violation of the 

24-hour PM10 standard occurs, Lowest Achievable Emission Rate requirements, plus 

offsets, for major new industrial sources in the UGB will be restored and the exemption 

for offsets eliminated.”

The problem:

ODEQ discontinued PM10 monitoring due to budget cuts and low PM10 levels. The 

contingency plan relies on continued PM10 monitoring to compare to the trigger points. 

ODEQ needs to adopt a trigger point based on an alternative pollutant measure.

The Solution:

The PM10 alternative pollutant measure will be to use PM2.5 monitoring as a surrogate. The 

PM2.5 relationship to PM10 has been established in recent years with collocated PM10 and 

PM2.5 monitors. Linear regression analysis was performed on the PM10 and PM2.5 data 

(Figure 3) and a linear regression equation was established (Table 6). Using this linear 

regression equation, DEQ has determined the PM2.5 concentration needed to trigger the PM10

trigger of 120μg/m3. This is shown in Table 6.

Table 6. Linear regression equations and ratios used to estimate PM10 using PM2.5.

Klamath Falls Grants Pass

Linear Regression Equation y = 1.4x + 3.2 y = 1.2x + 2.6

PM2.5 trigger for “Risk of Violation” 94 μg/m3

PM2.5 trigger for “Actual Violation” 105 μg/m3

PM2.5 trigger for 120 μg/m3 PM10 101 μg/m3

Y = PM10, X = PM2.5

8. Conclusion

Budget cuts have forced ODEQ and LRAPA to cut CO and PM10 monitoring where they are 

required by the maintenance plans for compliance determination and contingency measure 

triggers. Fortunately, the CO and PM10 levels are so far below the NAAQS that there is very 

little probability that the monitors would trigger the contingency plans. Regardless, the 

maintenance plans need ambient levels for comparison, so alternative methods are needed to 

estimate concentrations. The alternative contingency plans described in this document will 
15 15

15

Monitoring Discontinuation Justification

allow ODEQ and LRAPA to track CO and PM10 levels into the future. If levels start trending 

back up near the NAAQS, funding from other monitoring can be shifted and CO and PM10

monitors restarted. This is very unlikely however. 

Finally, monitoring is only required during the first 20 years of the maintenance plan. The 

monitoring requirement for Eugene/Springfield CO expires in 2014. The monitoring 

requirements for Medford CO will expire in 2023 and for Grants Pass PM10 and Klamath 

Falls PM10, the monitoring requirements will expire in 2023.

9. Reference

1. Air Quality Conformity Determination, Central Lane MPO FFY10-13 Metropolitan 

Transportation Improvement Program and 2007-2031 Regional Transportation Plan, 

October, 2010.

2. Air Quality Conformity Determination for 2010-2013. Metropolitan Transportation 

Improvement Program & 2009-2034 Regional Transportation Plan – Amended, Rogue 

Valley MPO, April, 2010.