Prevention of Significant Deterioration (PSD) Permits

The Prevention of Significant Deterioration (PSD) program applies to the construction of new major stationary sources and to major modifications of existing major stationary sources.  PSD also applies to modifications of existing minor stationary sources if the modification itself would constitute a major source.


The basic goals of the PSD program are to:


§                ensure that economic growth will occur in harmony with the preservation of existing clean air resources;

§                protect the public health and welfare from any adverse effects that might occur, even at air pollution levels better than the NAAQS; and

§                preserve, protect, and enhance the air quality in areas of special natural, recreational, scenic or historic value, such as national parks and wilderness areas (Class I Areas).


Because PSD is pollutant-specific, a significant net emissions increase of one pollutant subjects an affected source to PSD for that pollutant only.  It is important to note that a source that is major for one pollutant can trigger PSD requirements due to a significant net emissions increase of any NSR regulated pollutant.  For example, if NOx and CO emissions exceed 250 TPY, a 15 TPY net increase in PM10 emissions is subject to PSD review, even if facility-wide PM10 emissions are below the PSD major stationary source threshold.


PSD procedures are set forth in LAC 33:III.509.  All parishes in Louisiana are in compliance with the NAAQS for particulate, SO2, NOx, and CO; therefore, increases of these pollutants are evaluated pursuant to PSD regulations.  With the exception of the Baton Rouge Nonattainment Area (BRNA), which is designated as a marginal 8-hour ozone nonattainment, all parishes in the state are also in compliance with the NAAQS for ozone.  Thus, VOC increases outside of the BRNA are evaluated against PSD regulations, whereas VOC increases within the BRNA are reviewed pursuant to Nonattainment New Source Review (NNSR) regulations.  In the BRNA, NOx is both an attainment and nonattainment pollutant (due to the compound’s ability to contribute to ozone formation), so both PSD and NNSR are potentially applicable.


PSD Permits


Prior to commencement of construction of any project that would trigger PSD, a PSD permit must be obtained from the LDEQ.


A Single Project Can Trigger Both PSD and NNSR


Because New Source Review (which encompasses both NNSR and PSD) is pollutant-specific, it is important to note that a permit application may require both PSD and NNSR reviews.  For example, East Baton Rouge (EBR) Parish is in attainment with the NAAQS for all criteria pollutants except ozone.  Therefore, a permit application proposing a significant net emissions increase of both VOC (a nonattainment pollutant in EBR Parish) and CO (an attainment pollutant in Louisiana) would require that the VOC increase be evaluated in accordance with NNSR procedures, whereas the CO increase would be reviewed in accordance with PSD regulations.

Notification of the Federal Land Manager

Related Topics


Extended discussions of the following topics will appear in LDEQ’s revised Air Permit Procedures Manual.

§   PSD Applicability;

§   PSD Requirements;

§   Plantwide Applicability Limits (PALs);

§   Commencement of Construction;

§   How LAC 33:III.509 Differs from the Federal PSD Rule (at 40 CFR 51.166);

§   NNSR, PSD, and NOx Increases in the Baton Rouge Nonattainment Area; and

§   EPA’s Equipment Replacement Rule and Routine Maintenance, Repair, and Replacement.


Other Online Resources


In additional to the Air Permit Procedures Manual, other resources include:

EPA’s NSR Website

EPA’s New Source Review Policy and Guidance Database 

Louisiana Department of Environmental Quality 602 N. Fifth Street Baton Rouge, LA 70802
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