Southeastern State Air Pollution Control Agencies

Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, West Virginia

June 29, 2012

Air and Radiation Docket

Docket ID No. EPA-HQ-OAR-2010-1059

U.S. EPA Mail Code: 6102T

1200 Pennsylvania Avenue NW

Washington, DC 20460

RE: Comments on 1-hour SO2 NAAQS

 Implementation White Paper

Dear Docket Coordinator:

Thank you for the opportunity to comment on the Environmental Protection Agency 

(EPA) Office of Air and Radiation’s draft white paper on implementation of the 2010 

primary 1-hour sulfur dioxide (SO2) National Ambient Air Quality Standard (NAAQS). 

The implementation process is extremely important to the air pollution control agencies 

in the Southeast.

Background.

On June 2, 2010, EPA promulgated a revised SO2 primary standard which established 

a 1-hour standard of 75 parts per billion. In March and September 2011, EPA provided 

states with draft guidance on designations and implementation that prompted comments 

from many states. On April 12, 2012, EPA announced in letters to our state 

environmental commissioners that 1) EPA intended to move forward with the 

designation process for those areas with violating monitors, 2) EPA would initiate 

focused stakeholder forums to help EPA refine their approach to determining whether 

air quality in a given area is meeting the SO2 NAAQS, and 3) EPA no longer expected 

the infrastructure SIP submittals to contain modeling demonstrations showing 

attainment of the standard in unclassifiable areas.

On May 22, 2012, EPA released a revised white paper to describe a revised approach

for implementation of the primary 1-hour SO2 standard. In particular, the white paper 

focused on the determination of whether the air quality in a given area currently meets 

the NAAQS. EPA sought stakeholder input through the aforementioned forums as well 

as directly to the docket to which this letter is addressed. Our comments and 

recommendations herein are designed to address key issues from the white paper as

well as issues raised during the state, local, and tribal stakeholder forum held on May

31, 2012 in Durham, North Carolina. It is our desire to assist EPA in designing an 

effective and efficient approach to implementation of the 1-hour SO2 standard including 

how to determine if areas are meeting the 1-hour SO2 NAAQS.
Docket No. EPA-HQ-OAR-2010-1059

SO2 Implementation Comments

June 29, 2012

Page 2 of 6

Nonattainment Designations.

The undersigned support EPA’s approach as noted in its April 12, 2012 letter to the 

state environmental commissioners to designate areas based on violating monitors. 

Nonattainment designations should always be based on quality-assured monitoring

data. There must be ambient data demonstrating that SO2 levels are above the 

standard before EPA initiates designation of any area as not attaining the standard. 

While modeling may be appropriate in evaluating permit applications, siting ambient 

monitors, and determining whether a monitoring waiver is appropriate (see related 

information herein), modeling should not be used as the basis for determining and 

designating the attainment status of an area. We strongly encourage EPA to clearly 

state in the SO2 designations to be promulgated in the Federal Register that modeling 

should not be used to determine that air quality in a given area does not meet the 

NAAQS.

Preferred Approach for Unclassifiable Areas with Large SO2 Emission Sources. 

We offer the following suggested approach for determining whether an area is meeting 

the 1-hour SO2 NAAQS:

1. SO2 monitoring network requirements. 

We recognize that existing SO2 monitoring requirements were not designed with 

source specific locations as a primary siting criterion. If EPA decides that additional 

monitoring including source-oriented monitoring is needed, then the additional 

requirements should be established through the rulemaking process with an 

adequate opportunity for public comment. The implementation schedule should 

consider available resources. With that in mind, a structured phase-in schedule 

should be developed. The phase-in schedule for source-oriented monitoring should 

be prioritized based upon an actual emissions threshold. 

EPA should establish a requirement for a first phase of monitor installations to be 

completed by January 1, 2015 and a second by January 1, 2017. The emissions 

thresholds used in this approach should be established through rulemaking, and 

should consider anticipated future SO2 emissions after full implementation of major 

rules impacting these emissions such as the 2011 Cross- State Air Pollution Rule 

(CSAPR), the 2011 Mercury and Air Toxics Standards (MATS) Rule, and the 

reconsidered maximum achievable control technology (MACT) standards for 

industrial, commercial, and institutional boilers (the Boiler MACT) along with all 

associated installation and operating costs. Further, as implementing agencies 

prioritize the placement of monitors consistent with this emissions threshold 

approach, they should be allowed to consider other factors such as
Docket No. EPA-HQ-OAR-2010-1059

SO2 Implementation Comments

June 29, 2012

Page 3 of 6

population and source stack height. This approach would allow states to focus their 

resources in areas with the highest risk to public health and the largest sources of 

SO2 emissions. 

States should have flexibility to determine the location of source-oriented monitors 

as well as the appropriate number of monitors surrounding a given source. States 

should have the discretion to use modeling, wind rose information, and other tools to 

help with properly siting the monitors. Based on the results of initial phased-in data 

collection efforts, states should be given reasonable flexibility to relocate existing 

monitors to other sites. 

Funding for an expanded SO2 monitoring network was a significant issue discussed 

during the May 31, 2012 stakeholder forum. EPA should consider in its 

implementation planning the costs of purchase, installation, maintenance, and 

operation of all new monitoring equipment associated with revisions to the SO2

NAAQS. Given the financial challenges of most state environmental agencies, EPA 

should, at a minimum, fund through Section 103 grants the installation costs for all 

additional SO2 monitors required for the new standard. 

Some states have noted in recent feedback to EPA that one approach could include 

requiring sources to install and operate monitors. As a group, we are neutral on the 

option of sources funding the monitoring although each agency reserves the right to 

file individual comments. If EPA chooses to advocate monitoring by the sources, 

states should be given full oversight to validate that monitoring is carried out 

according to acceptable practices through establishment of a Quality Assurance 

Project Plan (QAPP). Alternatively, EPA should provide a mechanism for funding to 

come to the states to support operation of the monitors as part of their own 

monitoring networks.

If a source-oriented monitoring requirement is established, EPA should also develop 

an exception to this requirement. Sources should be able to use modeling to avoid 

the monitoring requirement much like what was allowed in the lead source 

monitoring program. If a source models at less than a predetermined threshold 

percentage of the standard, a source-oriented monitor should not have to be 

installed. The CSAPR, MATS and Boiler MACT rules are expected to reduce SO2

emissions from the largest sources. Projected actual emissions after subject 

sources have installed all required emission reduction strategies should be

included in the exception analysis to determine if source-oriented monitoring is 

necessary. 

2. Addressing future violations at source-oriented monitors. 
Docket No. EPA-HQ-OAR-2010-1059

SO2 Implementation Comments

June 29, 2012

Page 4 of 6

EPA should allow a state to address a source-oriented ambient air quality violation 

using the air program permitting process if a violation is measured in an unclassified

area after an ambient monitoring network is expanded. This may be the most 

efficient way to bring an area back into compliance with the NAAQS and is an 

appropriate federally-enforceable instrument to use. Given the short term nature of 

the SO2 standard and the typical cause and effect relationship between an individual 

source of SO2 and a violating monitor, the traditional designation process is not wellsuited to efficiently address such violations. If a state does not address a violation in 

a timely manner, then EPA could proceed with designating an area as 

nonattainment and follow the SIP development process at that time.

3. Monitoring exit strategy. 

EPA should establish a mechanism allowing monitors to be shut down as sources 

reduce their SO2 emissions and the ambient concentrations decrease. Currently, for 

other criteria pollutants, EPA allows monitors to be shut down once the ambient 

concentrations are 85 percent of the standard. This is an appropriate level for 

discontinuing the operation of a source-oriented SO2 monitor. This exit strategy for 

monitoring should be clearly defined in the monitoring rulemaking.

Preferred Approach for Unclassifiable Areas with No (or Insignificant) SO2 Emission 

Sources.

EPA should simplify the approach for addressing unclassifiable areas that fall below a 

set threshold. During the May 31 stakeholder forum, EPA noted a threshold that would 

capture 90% of the national SO2 emissions. If EPA were to require monitoring of 

ambient air quality around sources with actual emissions greater than or equal to a 

threshold, then counties having no sources at or above this threshold, and not being 

impacted by significant emissions from a source in an adjacent county, should be 

designated attainment or unclassifiable/attainment. Under this scenario, only those 

counties with sources whose emissions are above the SO2 threshold should be 

designated unclassifiable and they should only be maintained in that classification until 

ambient monitoring determines the area is attaining or violating the SO2 standard. 

Section 110(a) Infrastructure SIP Requirements.

EPA has suggested a reasonable revised approach for the SO2 infrastructure SIPs that 

are prescribed by June 2013. The criteria for such SIPs should be identical to the 

criteria for other criteria pollutant infrastructure SIPs. States should only be required to 

incorporate in the SO2 SIPs the procedures that will be used to implement the new 

standard.
Docket No. EPA-HQ-OAR-2010-1059

SO2 Implementation Comments

June 29, 2012

Page 5 of 6

Modeling.

The SO2 implementation white paper discussed a hybrid approach for monitoring and 

modeling. We do not support using modeling to determine whether an area is meeting 

the NAAQS for designation purposes.

If EPA chooses to require or allow modeling as part of a hybrid approach, EPA should

establish in rulemaking the criteria to be used to determine which sources must be 

modeled (e.g., a certain emissions threshold.) Further, EPA should allow a sufficient 

timeline for development of modeling protocols, conducting the modeling, establishing 

on-site meteorological monitoring, and collecting meteorological data if deemed 

necessary for production of reliable modeling results. Lastly, EPA should provide 

adequate funding for such efforts.

EPA should also allow the use of appropriate emissions rates. The use of a single 

maximum allowable emission rate for modeling compliance with short-term averages is 

unrealistic because it usually does not represent the distribution of hourly emissions on 

an annual basis. EPA should allow the use of actual emission rates and statistically 

representative emissions profiles when these data are deemed to be sufficiently 

reliable. This approach could include the use of continuous emission monitoring system 

data. EPA should allow sufficient time for states and the regulated community to collect 

onsite meteorological and ambient air measurements, and to evaluate model 

performance when necessary. The availability of onsite data is a key factor to ensuring 

credible model results.

Conclusions.

We strongly believe that nonattainment designations should never be based on 

modeling. Modeling may be appropriate in the permitting process, determining the best 

location for siting a monitor, or determining whether a monitoring waiver is appropriate, 

but it should never be used to determine if an area is violating a NAAQS for designation 

purposes. We strongly encourage EPA to designate counties that are below a set 

threshold as attainment or unclassifiable/attainment. 

The overall costs for implementing the short-term SO2 standard are significant, 

regardless of which approach is ultimately followed. EPA should design an 

implementation strategy that will best use limited state resources to address real air 

quality issues. EPA should not set up an implementation strategy that mandates the 

investment of time and energy for investigation and analysis of theoretical problems 

produced by the model, or unnecessary paperwork that does not achieve real emissions 

reductions and real air quality improvements.
Docket No. EPA-HQ-OAR-2010-1059

SO2 Implementation Comments

June 29, 2012

Page 6 of 6

We appreciate the opportunity to provide comments and recommendations on the 

implementation of the 1-hour SO2 standard. We reserve the right to supplement these 

comments with additional state-specific comments to the docket. We acknowledge the 

efforts EPA undertook to set up the stakeholder forums and the docket for receiving 

comments. We are very interested in being active, ongoing stakeholder participants 

throughout the implementation process. We stand ready to assist EPA with potential 

concepts prior to its proposing of a final implementation strategy. 

If you should have any questions please contact any of the undersigned or John E. 

Hornback, Executive Director, Southeastern States Air Resource Managers, Inc. The 

latter may be reached at 404-361-4000 or hornback@metro4-sesarm.org.

Sincerely,

Ronald W. Gore, Chief

Alabama DEM, Air Division

Michael P. Halpin, Director

Florida DEP, Division of Air Resource 

 Management

James A. Capp, Chief

Georgia EPD, Air Protection Branch

John S. Lyons II, Director

Kentucky DEP, Division for Air Quality

Maya Rao, Chief

Mississippi DEQ, Air Division

Sheila C. Holman, Director

North Carolina DENR, Division of Air 

 Quality

Myra C. Reece, Chief

South Carolina, DHEC Bureau of Air 

 Quality Control

Barry R. Stephens, Director

Tennessee DEC, Division of Air Pollution 

 Control

John A. Benedict

West Virginia, DEP Division of Air Quality

Copy: Beverly Banister, EPA Region 4, APTMD