UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

RESEARCH TRIANGLE PARK, NC 27711 

AUG 1 0 2005 

OFFICE OF 

MEMORANDUM 

AIR QUALITY PLANNING 

AND STANDARDS 

SUBJECT: Consideration ofMultipl~· Pol ~(Sin ¥n ol Strategy Development 

Stephen D. Page, Director l·---( <-

Office of Air Quality Pl~ ing and Stan~s (C404-04) 

FROM: 

TO: Air Division Directors, Regions I-X 

I am writing to update you on our efforts to support multipollutant approaches in 

developing state implementation plan (SIP) control strategies and to enlist your support in 

encouraging States to start moving towards the development of such strategies. We are asking 

for your input on the tools and/or guidance needed to support development ofmultipollutant 

control strategies and for examples ofmultipollutant control strategies and/or multipollutant SIPs 

that have already been created. 

In addition, I am requesting that each Regional office provide us with the name of a 

contact person by August 22, 2005 to: 1) work with us during the guidance development 

process; and 2) provide us with recommendations for tools, information, and guidance needed 

for developing multipollutant control strategies by August 29, 2005. 

As you are aware, the National Research Council (NRC) of the National Academies 

formed the Committee on Air Quality Management (AQM) in the United States in response to a 

congressional request for an independent evaluation of the overall effectiveness of the CAA. In 

their January 2004 report, Air Quality Management in the United States, the Committee made 

several recommendations. One recommendation was to transform the SIP into a comprehensive 

air quality management plan (AQMP) that would: 1) encompass all criteria pollutants for which 

a State has not attained the National Air Ambient Quality Standards; 2) include key hazardous 

air pollutants (HAPs); and 3) identify and propose control strategies for air pollution hot spots. 

In June 2004, the Clean Air Act Advisory Committee (CAAAC) formed the AQM Work 

Group, which was tasked with assessing the recommendations made in the 2004 NRC report and 

advising the CAAAC on ways to improve the AQM system in the U.S. Specifically, the 

CAAAC charged the Work Group with outlining concrete steps that could promote change in the 

direction recommended by the NRC. The Work Group provided 38 recommendations, and one 

of these, Recommendation 4.1, states that "for the SIPs States are required to submit over the 

next several years, EPA and States, locals, and Tribes should promote the consideration of 

multipollutant impacts, including the impacts of air taxies, and where there is discretion, select 

regulatory approaches that maximize benefits from controlling key air taxies, as well as ozone, 

PMz.s and regional haze." The CAAAC accepted a1138 recommendations and EPA is moving 

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2 

forward to implement them. At its core, Recommendation 4.1 is based on the NRC's long-term 

vision of creating a multipollutant, integrated AQMP. While multipollutant SIPs are not 

required by the CAA, the CAAAC believed that there are opportunities for testing this concept in 

the short-term. 

The SIP planning efforts are already underway for many areas. Clearly, States have a 

very demanding schedule for meeting the SIP submittal deadlines, and they are working with 

limited resources. However, I believe that States need to move forward in considering 

multi pollutant control strategies. With a modest amount of additional attention, a State could test 

and/or implement multipollutant planning approaches during the current SIP planning process. 

Though a multipollutant approach to assessing control strategies would require additional work 

in the near term, the long-term benefits are likely to be significant, both environmentally and 

economically. By taking steps toward a multipollutant approach for control strategy 

development, a State should be able to make better use oflimited resources and improve its 

ability to develop control strategies that optimize the mix of controls for multiple pollutants. 

While there is no federal regulatory requirement for States to reduce individual toxic air 

pollutants to any specific ambient level, there are federal requirements for categories of sources 

of toxic air pollutants, many of which contribute to the formation of ozone, PM2.5, and/or 

regional haze. We recognize that, by taking a multipollutant approach, improvements in air 

quality and human health can be obtained if air toxics, especially high-risk air toxics, are 

reduced. To facilitate the multipollutant approach in SIP development, we are revisiting our 

approach to regulating toxic air pollutants. For example, we are evaluating opportunities to use 

the authorities under section 112 of the CAA, particularly the delegation authorities in section 

112(1), to facilitate the use of SIPs for joint planning for relevant source categories. In this way, 

States could make improvements in air quality by considering air toxics reduction potential when 

selecting specific control strategies through the SIP process. 

I encourage you to work with the States in your Region to encourage them to start taking 

a multipollutant approach in developing control strategies as part of their air quality planning. 

An EPA multipollutant control strategy team has been formed which consists of representatives 

from the Office of Air Quality Planning and Standards (OAQPS), the Office of Transportation 

and Air Quality (OTAQ), the Office ofPolicy, Analysis and Review (OPAR), the Office of 

Atmospheric Program's Clean Air Markets Division (CAMD), and Region V. To provide some 

immediate assistance to States in initiating multipollutant control strategies, the team has 

developed the attached 3-page document, "Preliminary Approach for Identifying Toxic Air 

Pollutants for Consideration in Multipollutant Control Strategies." The attachment includes: 1) a 

working definition of"multipollutant control strategy"; 2) an initial list of key toxic air pollutants 

to consider, as well as a website address that provides a list of key area source categories for 

toxic air pollutants; and 3) a summary description of an approach that an area can use to develop 

its own list of toxic air pollutants with a link to a website describing a more detailed approach to 

identifying local toxic air pollutants. 
3 

In the longer term, we are planning to develop more detailed and comprehensive 

guidance on multipollutant control strategy development. With that in mind, we have initiated a 

pilot project in Detroit to evaluate multipollutant control strategy development for an urban area. 

The goal is to incorporate the information gained from this pilot project into additional guidance 

by early 2006. 

Before we proceed further with guidance development, I would appreciate your input in 

two important areas. First, I would like to know your thoughts about the information and/or 

tools that State, local, and Tribal (S/LIT) groups will need in order to pursue the development of 

multipollutant control strategies. I would ask that you survey your States for their input as well. 

Second, we would like information about cases in which a S/LIT group has considered multiple 

pollutants in the process of developing a SIP and/or has created a ')oint" or multipollutant SIP. 

Please send information on any examples ofmultipollutant control strategies and/or 

multipollutant SIP development to Amy Vasu of my staff. 

By August 22,2005, please send an email to Lydia Wegman (wegman.lydia@epa.gov) 

and to Amy Vasu of my staff(vasu.amy@epa.gov) with the name of a contact person who will 

provide us with your recommendations and work with us during the guidance development 

process. I also ask that this contact provide your recommendations, and those of your States, by 

email to Lydia Wegman and Amy Vasu by August 29,2005. We will also be requesting input 

from S/LIT representatives and others at the 2005 Air Innovations conference in Chicago 

(http://www.cleanairinfo.com/airinnovations2005) during the August 25 breakout session on 

multipollutant control strategy development. The recommendations you and others provide will 

inform the EPA team on how best to focus its efforts with regard to further development of tools, 

information, and guidance to assist S/LIT groups in developing multipollutant control strategies. 

In conclusion, I ask that you share this information, as well as the attached summary, 

with your States and encourage them to take a multipollutant approach in developing control 

strategies as part of their SIPs. If you have any questions, please contact Amy Vasu at (919) 

541-0107. 

Attachment 

cc: Joe Paisie 

Tom Helms 

Penny Lassiter 

Marypat Tyson (Region V) 

Lydia Wegman 
I. Background 

Preliminary Approach for Identifying Toxic Air Pollutants 

for Consideration in Multipollutant Control Strategies 

8/10/05 

In 2002, the National Research Council (NRC) of the National Academies formed the 

Committee on Air Quality Management in the United States in response to a congressional request 

for an independent evaluation of the overall effectiveness of the Clean Air Act (CAA). In their 

January 2004 report, Air Quality Management in the United States, the Committee made several 

recommendations. One recommendation was to transform the state implementation plan (SIP) 

into a comprehensive air quality management plan (AQMP) that would: (1) encompass all criteria 

pollutants for which a State has not attained the NAAQS; (2) include key hazardous air pollutants 

(HAPs); and (3) identify and propose control strategies for air pollution hot spots. 

In June 2004, the Clean Air Act Advisory Committee (CAAAC) formed the Air Quality 

Management Work Group, which was tasked with assessing the recommendations made in the 

2004 NRC report and advising the CAAAC on ways to improve the AQM system in the U.S. 

Specifically, the CAAAC charged the Work Group with outlining concrete steps that could 

promote change in the direction recommended by the NRC. The Work Group provided 38 

recommendations, including Recommendation 4.1, which states that "for the SIPs States are 

required to submit over the next several years, EPA and States, locals, and Tribes should promote 

the consideration of multipollutant impacts, including the impacts of air toxics, and where there is 

discretion, select regulatory approaches that maximize benefits from controlling key air toxics, as 

well as ozone, PM2.5 and regional haze." The CAAAC accepted these recommendations, and now 

EPA is moving forward to implement them. At its core, Recommendation 4.1 is based on the 

NRC long-term vision of creating a multipollutant, integrated AQMP. While multipollutant SIPs 

are not required by the CAA, the CAAAC believed that there are opportunities for testing this 

concept in the short-term. 

II. What is the objective of this document? 

The objective of this document is to provide information to the States to support their 

moving toward the goal of multipollutant SIPs by taking steps to evaluate multiple pollutants and 

develop multipollutant control strategies. This document includes: 1) a working definition of 

"multipollutant control strategy"; 2) an initial list of key toxic air pollutants to consider, as well as 

a website address that provides a list of key area source categories for toxic air pollutants; and 3) a 

summary description of an approach that an area could use to develop its own list of toxic air 

pollutants and source categories. This is intended to be an interim document that will be replaced 

within a year by a guidance document which is currently under development. 

III. What is a multipollutant control strategy? 

A multipollutant control strategy is a strategy for reducing pollutant emissions that 

considers two or more groups of pollutants in selecting control strategies, with the goal of 

selecting a control strategy that optimizes the mix of controls for multiple pollutants. Two or 

more of the following groups of air pollutants should be included: 1) ozone and its precursors; 2) 

PM2.5 and its precursors; and 3) one or more toxic air pollutants. As an example, in developing a 
multipollutant control strategy for an area that is a nonattainment area for PM2.s, but which is in 

attainment with the ozone NAAQS, a State might focus on PM2.5 and its precursors, as well as on 

selected toxic air pollutants that pose high risk and/or contribute to PM2.5 (as direct PM or as PM2.s 

precursors). 

IV. Why should a State/local/Tribal entity develop a multipollutant control strategy? 

A State/locaVTribal entity should develop a multipollutant control strategy for several 

reasons: 

• to prepare for the future I move in the direction of having integrated, multipollutant 

control strategy; 

• to assist an area in reaching attainment in a more cost-effective and efficient manner 

with greater overall reductions of pollutants; 

• to promote an optimal mix of control measures for multiple pollutants and to avoid 

control measures that, while beneficial in reducing one pollutant, may result in 

increases in another; 

• to better utilize limited State/locaVTribal resources, and those of the regulated 

community, for improving air quality; and 

• to make it easier for potentially affected sources to plan installation of controls, rather 

than having to install controls in a piecemeal fashion. 

V. What are the steps in identifying toxic air pollutants for consideration in developing a 

multipollutant control strategy? 

Once areas, and criteria pollutants of concern in those areas, have been identified, a 

State/locaVTribal entity could use the following three-tiered approach to select toxic air pollutants 

for consideration in developing a multipollutant control strategy for a particular area. The first tier 

contains a short list of 3 toxic air pollutants that have been identified as national risk drivers by the 

National Air Taxies Assessment (NATA) National Scale Assessment for 1999. The second tier 

includes a list of some toxic air pollutants that occur in many areas of the U.S. that, due to 

emission levels and toxicological properties, may pose high risks. 1 The third tier presents an 

approach for identifying toxic air pollutants of concern that can be used for assessing a local area. 

Additional information on the 1999 NATA National Scale Assessment will be available in fall 

2005 at: http://www.epa.gov/ttn/atw/nata/. 

1) Tier 1: Evaluate a "short list" of toxic air pollutants that are nationally-occurring and that 

have the potential to pose high risks to human health in urban areas: 

• Benzene 

• Acrolein 

• Diesel PM 

1 This is a subset of the toxic air pollutants identified by the 1999 NATA National Scale Assessment as "regional risk 

drivers." More information will be available in fal12005 at: http://www.epa.gov/ttn/atw/nata/. 

2 
The file "99 NATA Risk Drivers EI Pie Charts.ppt" (at 

http://www.epa.gov/air/caaac/aqm.html, under "document library'') contains pie charts 

showing the source category contributions of emissions for each of these toxic air 

pollutants. Information on area source categories of toxic air pollutants is provided at: 

http :1/www .epa.gov/ttn/atw/urban/arearules.html. 

2) Tier 2: Consider some additional toxic air pollutants that have been identified as being 

emitted by existing sources, as well as having the potential to cause cancer and/or 

noncancer effects: 

• Arsenic compounds 

• 1 ,3-Butadiene 

• Chlorine 

• Chromium VI 

• Coke oven emissions 

• Formaldehyde 

• Hydrazine 

• ~anganese compounds 

• Naphthalene 

• Nickel compounds 

• PARs 

• Tetrachloroethylene (Perchloroethylene) 

The file "99 NATA Risk Drivers EI Pie Charts.ppt" (at 

http://www.epa.gov/air/caaac/aqm.html, under "document library'') contains pie charts 

showing the source category contributions of emissions for each of these toxic air 

pollutants. Information on area source categories of toxic air pollutants is provided at: 

http://www.epa.gov/ttn/atw/urban!arearules.html. 

3) Tier 3: Identify any additional local toxic air pollutants. 

Areas can develop their own lists of toxic air pollutants using the NATA results by 

following the step-by-step approach provided in the 3-page file called "Use ofNATA data 

to Evaluate Area-Specific Toxic Air Pollutants of Concern" (at 

http://www.epa.gov/air/caaac/aqm.html, under "document library"). 

Note that this three-tiered approach focuses on pollutants that present inhalation risks 

(since the NATA national scale assessment only accounts for inhalation risks from outdoor 

pollutants) and, therefore, does not specifically highlight other significant pollutants (e.g., 

mercury) that have the potential to affect human health and ecosystems. A State/local/Tribal 

entity could choose to include such pollutants in their analyses, as well as in their selection of 

control measures. 

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