RULE 1-130 - DEFINITIONS 

Except as otherwise specifically provided in these rules and regulations, words used in these 

rules and regulations are used in exactly the same sense as the same words are used in the federal 

Clean Air Act Amendments of 1990 and as amended at the time of application, Title 40 of the 

Code of Federal Regulations, Part 52.21, and Division 26 of the State of California Health and 

Safety Code. Where Title 40 of the Code of Federal Regulations, Part 52.21 refers to the 

responsibilities of the Administrator of the U.S. Environmental Protection Agency, the term 

Administrator shall be construed to mean Air Pollution Control Officer. 

[Amended 5/6/03, Amended 12/5/06, Amended 2/15/11] 

(b2) Best Available Control Technology (BACT): 

An emissions limitation based on the maximum degree of reduction of each air 

contaminant subject to regulation under the federal Clean Air Act Amendments of 1990 

and as amended at the time of application emitted from or that results from any stationary 

or portable source or modification, which the Air Pollution Control Officer, on a case by 

case basis, taking into account energy, environmental, and economic impacts and other 

costs, determines is achievable for such stationary source through application of 

production processes and available methods, systems, and techniques for control of such 

air contaminants. Said BACT determinations may include a design standard, operational 

equipment specifications, fuel restrictions, work practice or combination thereof. In no 

event shall application of BACT result in emissions of any pollutants that will exceed the 

emissions allowed under Rules 1-490 and 1-492 of this regulation. If the reviewing 

authority determines that technological or economic limitations on the application of 

measurement methodology to a particular emissions unit would make the imposition of 

an emissions standard infeasible, a design, equipment, work practice, operational 

standard or combination thereof, may be prescribed instead to satisfy the requirements for 

the application of BACT (40 CFR 52.21(b)(12)). 

The BACT process shall be applied to any air contaminants that have been identified as 

toxic air contaminants (TAC) by the U.S. Environmental Protection Agency, the 

California Air Resources Board or the Mendocino County Air Quality Management 

District Board. 

[(b2) Paragraph 2 is not included as part of the SIP] 

(g2) Greenhouse Gases (GHGs): 

A gas that has the capacity to create a warming effect in the earth’s atmosphere; for the 

purposes of this rule: carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), 

hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).

[Added 2/15/11] 
(p1) Particulate Matter: 

Any material, except uncombined water, that exists in a finely divided form as a liquid or 

solid at standard conditions. Specific size fractions of particulate matter are defined as 

follows: 

1. PM2.5 means particulate matter, both filterable and condensable, with an 

aerodynamic diameter less than or equal to a nominal two and one half 

(2.5) micrometers. 

2. PM10 means particulate matter, both filterable and condensable, with an 

aerodynamic diameter less than or equal to a nominal ten (10) micrometers. 

[Amended 2/15/11] 

(p7) Precursor: 

A substance that, when released to the atmosphere, forms or causes to be formed or 

contributes to the formation of another or secondary air pollutant for which a national 

ambient air quality standard has been adopted, or whose presence in the atmosphere will 

contribute to the violation of one or more national ambient air quality standards. 

Presently identified precursors and secondary pollutants are: 

Precursors Secondary Pollutants 

Volatile Organic Compounds 

 a) Photochemical oxidants (ozone O3) 

b) Organic fraction of PM10 

Nitrogen Oxides (NOx) a) Photochemical oxidants (Ozone) 

b) Nitrogen dioxide (NO2) 

c) Nitrates NO3 

d) Nitrate fraction of PM10 

e) Nitrate fraction of PM2.5 

Sulfur oxides (SOx) a) Sulfur dioxide (SO2) 

b) Sulfates (SO4) 

c) Sulfate fraction of PM10 

d) Sulfate fraction of PM2.5 

[Amended 2/15/11] 
(p7) Prevention of Significant Deterioration (PSD) Increment: 

The maximum allowable increase of ambient air quality above baseline concentration in 

the three classified areas. 

Allowable PSD Increments 

micrograms per cubic meter 

Class I Class II Class III 

Sulfur Dioxide 

 Annual Arithmetic Mean 2 20 40 

 24-hour maximum* 5 91 182 

 3-hour maximum 25 512 700 

 

 Particulate Matter (PM 2.5) 

 Annual Arithmetic Mean 1 4 8 

 24-hour maximum* 2 9 18 

 

Particulate Matter PM-10 

 Annual Arithmetic Mean 4 17 34 

 24-hour maximum* 8 30 60 

 

Nitrogen Dioxide 

 Annual 

Arithmetic Mean

2.5 25 50 

* Not to be exceeded more than once a year. 

(s2) Significant: 

The potential of a new or modified source to emit air contaminants that would equal or 

exceed any of the following rates, calculated on the basis of 24-hour emissions profiles, 

except as noted otherwise: 

Air Contaminant Significant Emissions Rate 

Carbon monoxide 550 lbs. per day 

Nitrogen oxides 220 lbs. per day 

Sulfur dioxide 220 lbs. per day 

Particulate matter 135 lbs. per day 

PM-10 80 lbs. per day 

PM2.5 54 lbs. per day of direct PM2.5 emissions; 

 220 lbs. per day of sulfur dioxide emissions; 

 220 lbs. per day of nitrogen oxide emissions. 

Ozone 220 lbs. per day of VOCs * or nitrogen 

oxides 

Lead 3 lbs. per day 

Asbestos .038 lbs. per day 

Beryllium .002 lbs. per day 

Mercury 0.5 lbs. per day 

Vinyl chloride 5.4 lbs. per day 

Fluorides 16 lbs. per day 

Sulfuric acid mist 38 lbs. per day 
Hydrogen sulfide (H2S) 54 lbs. per day 

Total reduced sulfur (including H2S) 54 lbs. per day 

Reduced sulfur compounds 

 (including H2S): .027 lbs. per day 

Municipal waste combustors: 

Organic emissions: 3.2 × 10-6 megagrams per year (3.5 × 10-6

tons per year) (measured as total tetrathrough octa-chlorinated dibenzo-p-dioxins 

and dibenzofurans) 

Metals emissions: 14 megagrams per year (15 tons per year) 

(measured as particulate matter) 

Acid gas emissions: 36 megagrams per year (40 tons per year) 

(measured as sulfur dioxide and hydrogen 

chloride) 

Municipal solid waste landfills: 

Nonmethane organic compounds: 45 megagrams per year (50 tons per year) 

Greenhouse Gases: 

For the purpose of Rule 1-220 only: as specified in Rule 1-221.4 (a) or 1-221.4 (c) 

For the purpose of Regulation 5 only: as specified in Rule 1-221.4 (b) 

Other pollutants regulated under the Clean Air Act: any emissions rate whatsoever 

(52.21(b)(23)(ii)). 

Hazardous Air Pollutant (HAP) 

 listed pursuant to Section 112(g) 

 of the federal Clean Air Act 

 Amendments of 1990 and as 

 amended at the time of application 10 tons per year of any one HAP 

 25 tons per year for two or more HAPs 

* Volatile Organic Compounds except for ethanol sources below the EPA 

yearly threshold (40 tons per year). 

Not withstanding the above significant emissions rates for various air contaminants, 

significant also means any net emissions increase from any new or modified stationary 

source that would be constructed within 10 kilometers of a Class I area and have an air 

quality impact on such area equal to or greater than 1 microgram per cubic meter (24 

hour average). (40 CFR 52.21(b)(23)(iii)) The above Significant Emissions Rates are not 

to be used for CEQA determination.