TECHNICAL SUPPORT DOCUMENT

Department of the Environment 

Amendments to Prevention of Significant 

Deterioration (PSD) Requirements 

under COMAR 26.11.01.01 and 26.11.06.14

Purpose of the Amendments 

The purpose of this action is to: 

 (1) update the adoption of the U.S. Environmental Protection Agency (EPA) Prevention of 

Significant Deterioration (PSD) federal requirements found under 40 CFR Part 52.21 to 

include the changes in the July 1, 2008 edition of the Code of Federal Regulations (CFR); and 

(2) clarify the meaning of the terms “Administrator” and “Reviewing Authority” as used in 40 

CFR Parts 52.21 and 52.1116. 

These amendments will be submitted to EPA for approval as part of Maryland's State 

Implementation Plan. 

Background 

The PSD program is a federal program that applies to new major stationary sources1

 or major 

modifications2 at existing sources for pollutants where the area in which the source is located is 

in "attainment" or "unclassifiable"3 with the National Ambient Air Quality Standards (NAAQS). 

The PSD program allows for growth in these areas by limiting emissions of air pollutants to 

prevent significant deterioration of air quality. 

PSD Requirements 

The PSD program requires installation of the "Best Available Control Technology (BACT)", air 

quality impact analyses and public involvement.

PSD requirements do not prevent sources from increasing emissions. Instead, they are designed 

to: 

 

1 Major Stationary Sources: This term, as defined in the Prevention of Significant Deterioration program, means 

any stationary pollutant source with potential to emit more than either 100 or 250 tons per year, depending upon the 

source category. 

2 Major Modification: This term is used to define modifications of existing major stationary sources of emissions 

with respect to Prevention of Significant Deterioration and New Source Review under the Clean Air Act. 

3

 There are no "unclassifiable" areas in Maryland. 

1 
1. protect public health and welfare; 

2. preserve, protect, and enhance the air quality in national parks, national wilderness areas, 

national monuments, national seashores, and other areas of special national or regional 

natural, recreational, scenic, or historic value; 

3. insure that economic growth will occur in a manner consistent with the preservation of 

existing clean air resources; and 

4. assure that any decision to permit increased air pollution in any area to which this section 

applies is made only after careful evaluation of all the consequences of such a decision 

and after adequate procedural opportunities for informed public participation in the 

decision making process. 

Best Available Control Technology (BACT) 

BACT is an emissions limitation which is based on the maximum degree of control that can be 

achieved. It is a case-by-case decision that considers energy, environmental, and economic 

impact. BACT can be add-on control equipment or modification of the production processes or 

methods. This includes fuel cleaning or treatment and innovative fuel combustion techniques. 

BACT may also be an equipment design, work practice, or operational standard if imposition of 

an emissions standard is infeasible. 

Air Quality Analysis Requirement

The main purpose of the air quality analysis is to demonstrate that new emissions emitted from a 

proposed major stationary source or major modification, in conjunction with other applicable 

emissions increases and decreases from existing sources, will not cause or contribute to a 

violation of any applicable NAAQS or PSD increment. 

Generally, the analysis will involve (1) an assessment of existing air quality, which may include 

ambient monitoring data and air quality dispersion modeling results; and (2) predictions, using 

dispersion modeling, of ambient concentrations that will result from the applicant's proposed 

project and future growth associated with the project. 

Additional Impacts Analysis Required

The additional impacts analysis assesses the impacts of air, ground and water pollution on soils, 

vegetation, and visibility caused by any increase in emissions of any regulated pollutant from the 

source or modification under review, and from associated growth. Associated growth is 

industrial, commercial, and residential growth that will occur in the area due to the source. 

PSD Increment

PSD increment is the amount of air pollution an area is allowed to increase. PSD increments 

prevent the air quality in clean areas from deteriorating to the level set by the NAAQS. The 

NAAQS is a maximum allowable concentration "ceiling." A PSD increment, on the other hand, 

is the maximum allowable increase in concentration that is allowed to occur above a baseline 

concentration for a pollutant. The baseline concentration is defined for each pollutant and, in 

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general, is the ambient concentration existing at the time that the first complete PSD permit 

application affecting the area is submitted. Significant deterioration is said to occur when the 

amount of new pollution would exceed the applicable PSD increment. It is important to note, 

however, that the air quality cannot deteriorate beyond the concentration allowed by the 

applicable NAAQS, even if not all of the PSD increment is consumed. 

Maryland's PSD Requirements 

The federal PSD regulations have been incorporated by reference under the Code of Maryland 

Regulations (COMAR) since 1981. The Department updates the COMAR reference to the PSD 

regulations each year or when the federal regulations undergo significant amendments. EPA has 

amended the federal regulations since the last update to the 2007 edition of the CFR. Therefore, 

it is necessary to update COMAR's reference to include the amendments reflected in the July 

2008 CFR. 

Sources Affected 

Major sources in "attainment" areas of the State that emit any pollutant subject to regulation 

under the Clean Air Act (NOx, SOx, particulate matter, etc.) are affected. A new major source is 

subject to PSD requirements if it is within a listed source category with projected emissions of at 

least 100 tons per year (listed under COMAR 26.11.01.01B(37(a); or a non-listed source with 

emissions of at least 250 tons per year of any regulated criteria pollutant . Additionally, lower 

emission thresholds apply to existing major sources undergoing a major modification. 

EPA Designation of Maryland Counties for the 8-hour Ozone Standard: 

All counties in Maryland are designated as "attainment" counties for the 8-hour ozone standard 

except the following: 

• Baltimore Area: Anne Arundel, Baltimore, Carroll, Harford, Howard, Baltimore City 

• Washington D.C. area: Calvert, Charles, Frederick, Montgomery, Prince George's 

• Cecil County 

• Kent and Queen Anne's (In Maintenance) 

EPA Designation of Maryland Counties for the Annual PM2.5 Standard: 

All counties in Maryland are designated as "attainment" counties for the annual PM2.5 standard 

except the following: 

• Baltimore Area: Anne Arundel, Baltimore, Carroll, Harford, Howard, Baltimore City 

• Washington D.C. area: Charles, Frederick, Montgomery, Prince George's 

• Washington County 

Changes made to the PSD requirements 

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(from July 1, 2007 - June 30, 2008 editions of the CFR)

Since the July 1, 2007 edition of the CFR, EPA made the following changes to the PSD program, 

which were incorporated into the July 1, 2008 edition of the CFR: 

EPA amended the definition of “major stationary source” in 40 CFR 52.21 (effective July 2, 

2007) to exclude ethanol production facilities from the requirement to include fugitive emissions 

in determining whether chemical process plants are major stationary sources. 72 FR 24066 (May 

1, 2007). 

EPA amended 40 CFR52.21(r)(6) (effective January 2, 2008) to clarify the recordkeeping 

requirements for a modification where there is a “reasonable possibility” that the change would 

result in a significant increase of any regulated New Source Review (NSR) pollutant. 72 FR 

72607 (December 21, 2007). 

Expected Emissions Reductions 

This regulation update will not reduce emissions from existing sources. 

Comparison to Federal Standards 

There is a corresponding federal standard to this proposed action, but the proposed action is not 

more restrictive or stringent. 

Estimate of Economic Impact 

This proposed action has no economic impact in and of itself, because it merely identifies EPA’s 

recent amendments to its PSD regulations. EPA’s PSD program is a federal program and EPA 

already accounted for the program's impact on all the affected sources on a nationwide basis. 

There is no additional impact on affected sources or the Department due to this proposed action. 

Economic Impact on Small Businesses 

This action will have no economic impact on small businesses because the affected sources are 

not “small businesses” as defined in State Government Article, §2-1505.2, Annotated Code of 

Maryland. 

L:\AQPlanning and Monitoring\Regulation Development Division\PSD\2009 PSD update\TSD\TSD for 2009 PSD amendments.doc