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7.4
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
DATE: February, 1981
SUBJECT: PSD Significance Levels for Monitoring
FROM: Darryl D. Tyler, Acting Director
Control Programs Development Division (MD-15)
TO: Director, Air and Waste Management Division, Regions I - X
The August 7, 1980, PSD promulgation introduced significance levels of
projected ambient impacts for the purpose of determining whether a proposed
source or modification would be eligible for an exemption from the
requirement for ambient monitoring. 40 CFR 51.24(i)(8) and 52.21(i)(8).
Typographical errors and miscalculations caused the numbers for either
concentration or averaging time printed in the August 7, 1980, document to
be incorrect for four pollutants. Those pollutants are nitrogen dioxide,
lead, beryllium, and hydrogen sulfide.
Attached is a copy of Table A-2 from Ambient Monitoring Guidelines for
Prevention of Significant Deterioration (PSD) (EPA-450/4-80-012, Nov. 1980,
revised Feb. 1981). In case these revisions have not yet come to your
attention, please note that the table contains the correct values and
supersedes earlier documents. We expect these values to be the subject of
future technical and conforming amendments, to appear in the Federal
Register. Should you have any further questions on this topic, you may
contact Michael Trutna at FTS 629-5591.
Attachment
TABLE A-2. SIGNIFICANT MONITORING CONCENTRATIONS |
Pollutant | Air Quality Concentration (ug/m3) and Averaging Time |
Carbon monoxide | 575 (8-hour) |
Nitrogen dioxide | 14 (annual) [see d] |
Sulfur dioxide | 13 (24-hour) |
Total suspended particulates | 10 (24-hour) |
Ozone | (see a below) |
Lead | 0.1 (3-month) [see d] |
Asbestos | (see b below) |
Beryllium | 0.001 (24.hour)[see e] |
Mercury | 0.25 (24-hour) |
Vinyl chloride | 15 (24-hour) |
Fluorides | 0.25 (24-hour) |
Sulfuric acid mist | (see b below) |
Total reduced sulfur (also H2S) | (see c below) |
Reduced sulfur (including H2S) | (see c below) |
Hydrogen sulfide | 0.2 (1-hour) [see e] |
- No specific air quality concentration for ozone is prescribed.
Exemptions are granted when a source's VOC emissions are <100
tons/year.
- No acceptable monitoring techniques available at this time. Therefore,
monitoring is not required until acceptable techniques are available.
- No acceptable monitoring techniques available at this time. However,
techniques are expected to be available shortly.
- The averaging times are corrected to be consistent with the averaging
time of the standard.
- These concentrations are corrected from the previous printing and are
approximately five times the minimum detectable concentrations. These
are consistent with other values in this table.
A-6 |