(Adopted Oct. 5, 1979)(Amended March 7, 1980)(Amended Sept. 10, 1982)

(Amended Dec. 3, 1982)(Amended July 12, 1985)(Amended August 1, 1986)

(Amended Sept. 5, 1986)(Amended June 28, 1990)(Amended May 3, 1991)

(Amended December 7, 1995)(Amended June 14, 1996)

RULE 1306. EMISSION CALCULATIONS

(a) General

This rule shall be used as the basis for calculating applicability of Regulation XIII as stated in 

Rule 1301(b) and Rule 1303. This rule shall also be the basis for calculating daily emission 

increases and decreases used for offset requirements and Emission Reduction Credits. 

(b) Emission Increases

Emission increases for new sources and the new total emissions for modified sources shall be 

calculated, as approved by the Executive Officer or designee, (1) using calendar monthly 

emissions divided by 30 for determination of the required amount of offsets, and (2) on a pound 

per day basis for determination of BACT and modeling applicability, from permit conditions 

which directly limit the emissions or, when no such conditions are imposed, from:

(1) the maximum rated capacity; and

(2) the maximum daily or monthly hours of operation as applicable; and

(3) the physical characteristics of the material processed.

(c) Emission Decreases

Emission decreases from sources which are modified or removed from service shall be the actual 

emissions reduced to the amount which would be actual if current BACT were applied. The 

emission amount shall be calculated from the following:

(1) The sum of actual emissions, as determined from company records, shall include annual 

emissions declarations pursuant to Rule 301, or other data approved by the Executive Officer or 

designee, whichever is less, which have occurred each year during the two-year period 

immediately preceding the date of permit application, or other appropriate period determined by 
the Executive Officer or designee to be representative of the source's cyclical operation, and 

consistent with federal requirements;

(2) The sum of BACT adjusted annual emissions shall be divided by the total number of actual 

operation days in each of those two years or other approved period; and

(3) The calculated amount from paragraphs (c)(1) and (c)(2) shall be multiplied by the usage 

factor appropriate to the use of the subject sources in each of the two years used for calculation, 

as follows:

1.0 when operated 180 days or more,

0.5 when operated 30 to 179 days, and

0.0 when operated less than 30 days.

(4) Daily emissions shall be determined for each year. The average value shall be calculated for 

those two years or other approved period.

The BACT adjustment shall not apply to facilities located in the SEDAB.

(d) Determination of Required Offsets and BACT Applicability

This subdivision shall be used for determining the amount of required offsets pursuant to Rule 

1303(b)(2), and BACT applicability pursuant to Rule 1303(a). 

(1) New Equipment Requiring a Permit (No Previous Permit).

Emissions are calculated pursuant to Rule 1306(b).

(2) Modification of Existing Source.

Net emissions increase after the modification shall be calculated pursuant to Rule 1306(b) which 

is the post-modification potential to emit minus either:

(A) the permitted or allowable pre-modification potential to emit; or

(B) the actual emissions calculated pursuant to Rule 1306(c)(1) if the source was never subject to 

Rule 213 or Regulation XIII.
(e) Determination of Emission Reduction Credit

This paragraph shall be used for determining all Emission Reduction Credits.

(1) All Modifications: 

Emission credit shall be based upon the new potential to emit calculated pursuant to Rule 

1306(b) minus the decrease calculated pursuant to Rule 1306(c).

(2) All Shutdowns: 

Emission credit shall be based upon the decrease calculated pursuant to Rule 1306(c).

(3) The ERC shall equal the emission credit at the facility determined pursuant to paragraphs 

(e)(1) or (e)(2) minus the following:

(A) The NSR balance of the facility. The NSR balance must be zero for any ERC to be granted;

(B) All Community Bank allocations;

(C) All Priority Reserve allocations; and

(D) All offsets obtained pursuant to the exemption provisions of Rule 1304.

(4) For the purpose of ERC determination in subparagraph (e)(3)(A) above, the NSR balance 

may be reduced from modifications and shutdowns by the amount of:

(A) the pre-modification potential to emit minus the post-modification potential to emit, for 

sources previously subject to Rule 213 or Regulation XIII; or

(B) the actual emissions calculated pursuant to Rule 1306(c) minus the post-modification 

potential to emit for sources never subject to Rule 213 or Regulation XIII.

For shutdowns, the post-modification potential to emit is zero. 

(f) Air Pollution Controls

For the modification of any source installed prior to October 8, 1976, resulting from the addition 

of air pollution controls installed solely to reduce the issuance of air contaminants, emissions 

shall be calculated, for purposes of Rule 1303 determination only, from permit conditions which 

directly limit the emissions or, when no such conditions are imposed, from:

(1) the maximum rated capacity; and

(2) the maximum proposed daily hours of operation; and
(3) the physical characteristics of the materials processed.

This subsection shall not be used to calculate an Emission Reduction Credit, which shall be 

determined by paragraphs (b), (c) and (e). 

(g) Mobile Sources

The following mobile source emission increases or decreases directly associated with the subject 

sources shall be accumulated:

(1) Emissions from in-plant vehicles; and

(2) All emissions from ships during the loading or unloading of cargo and while at berth where 

the cargo is loaded or unloaded; and

(3) Nonpropulsion ship emissions within Coastal Waters under District jurisdiction.

(h) PM10 Emissions

The PM10 emissions from an existing facility shall be calculated from the Total Suspended 

Particulate (TSP) emission increases and decreases which have occurred since October 8, 1976, 

using PM10 emission factors provided in the most recent AQMD California Environmental 

Quality Act (CEQA) Air Quality Handbook or as approved by the Executive Officer or designee