Section 204.660 Significant

a) "Significant" means, in reference to a net emissions increase or the potential of a source to emit any of the following pollutants, a rate of emissions that would equal or exceed any of the following rates:

Pollutant and Emissions Rate
Carbon monoxide	100 tpy
NO_X	40 tpy
SO₂	40 tpy
PM	25 tpy of particulate matter emissions
PM₁₀	15 tpy
PM_2.5	10 tpy of direct PM_2.5emissions; 40 tpy of SO₂ emissions; 40 tpy of NO_X emissions unless demonstrated not to be a PM_2.5 precursor under Section 204.610(a)(2)(C)
Ozone	40 tpy of VOM or NO_X
Lead	0.6 tpy
Fluorides	3 tpy
Sulfuric acid mist	7 tpy
Hydrogen sulfide (H₂S)	10 tpy
Total reduced sulfur (including H₂S)	10 tpy
Reduced sulfur compounds (including H₂S)	10 tpy
GHGs	75,000 tpy CO₂e
Municipal waste combustor organics (measured as total tetra-through octa-chlorinated dibenzo-p-dioxins and dibenzofurans)	3.2 ×10^-6 megagrams per year (3.5 ×10^-6 tpy)
Municipal waste combustor metals (measured as PM)	14 megagrams per year (15 tpy)
Municipal waste combustor acid gases (measured as SO₂ and hydrogen chloride)	36 megagrams per year (40 tpy)
Municipal solid waste landfills emissions (measured as nonmethane organic compounds)	45 megagrams per year (50 tpy)
Ozone depleting substances	100 tpy

b) "Significant" means, in reference to a net emissions increase or the potential of a source to emit a regulated NSR pollutant that subsection (a) does not list, any emissions rate.

c) Notwithstanding subsection (a), "significant" means any emissions rate or any net emissions increase associated with a major stationary source or major modification that would construct within 10 kilometers of a Class I area, and have an impact on that area equal to or greater than 1 μg/m³ (24-hr average).