Ill. Admin. Code tit. 35, § 204.660
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 |
| NOX | 40 tpy |
| SO2 | 40 tpy |
| PM | 25 tpy of particulate matter emissions |
| PM10 | 15 tpy |
| PM2.5 | 10 tpy of direct PM2.5 emissions; 40 tpy of SO2 emissions; 40 tpy of NOX emissions unless demonstrated not to be a PM2.5 precursor under Section 204.610(a)(2)(C) |
| Ozone | 40 tpy of VOM or NOX |
| 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 |