Illinois Environmental Protection Agency (IEPA)

EPA designated counties of Cook, DuPage, Kane, Lake, Will, some parts of Grundy and Kendall and the townships of Alux Sable, Goose Lake and Oswego in Chicago, as well as Madison and St. Clair Counties in St. Louis as marginal nonattainment for ozone according to the 2015 8-Hour Ozone Standard.

Based on the 2008 8-Hour Ozone Standard, Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry and Will Counties were moderately nonattainment for ozone.

For PM10, Madison County situated in Granite City in Nameoki Township, parts of Cook County and Lyons Township, which are both located in Lyons Township, parts of LaSalle County in Oglesby and parts of Cook County in Southeast Chicago were assigned as moderate maintenance for the pollutant.

Nonattainment areas for SO2 comprised parts of Madison County in Alton Township, parts of Cook and Will Counties and the townships of Lemont, DuPage, and Lockport in Lemont, parts of Peoria and Tazewell Counties and the townships of Hollis, Cincinnati, and Pekin in Pekin, and Williamson County.

To meet and reduce federal NAAQS standards for ozone especially for VOM and other criteria pollutants, IEPA maintains its ERMS program. This applies to any source located in the Chicago ozone nonattainment area that is required to have a Clean Air Act Permit Program (CAAPP) and has seasonal emissions of ≥10 tons of VOM. Moreover, ERMS also applies to a new participating source located in the Chicago ozone nonattainment area, that is required to obtain a CAAPP permit and has or will have seasonal emissions of ≥10 tons of VOM.

Illinois’ allotment trading units (ATUs) are available for five different pollutants:

Pollutant Significant Emission Rates
Nitrogen oxides (NOx) >100 tons/year (marginal – moderate)
>50 tons/year (serious)
>25 tons/year (severe)
>10 tons/year (extreme)
Volatile organic material (VOM) >100 tons/year (marginal – moderate)
>50 tons/year (serious)
>25 tons/year (severe)
>10 tons/year (extreme)
Sulfur dioxide (SO2) >100 tons/year
Carbon monoxide (CO) >100 tons/year (marginal – moderate)
>50 tons/year (serious)
PM10 >100 tons/year (moderate)
>70 tons/year (serious)

New or modified major facilities in nonattainment areas must obtain ERCs to satisfy the offset ratio requirements for proposed emission increases. Marginal nonattainment areas for ozone in Illinois including Cook, DuPage, Kane, Lake, Will, some parts of Grundy and Kendall and the townships of Alux Sable, Goose Lake and Oswego in Chicago, and Madison and St. Clair Counties in St. Louis, have offset ratio equal to 1.1 to 1. That means if 100 tpy of VOCs are emitted from a proposed new or modified major facility in a marginal nonattainment area in Illinois, the facility must obtain 110 tpy of ERCs to offset the increase in VOC emissions.

On the other hand, offset ratios the counties of Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry and Will, which were designated as moderate nonattainment areas for ozone (2008 Standard) is 1.15. That means 115 tpy of VOC ERCs are required from the proposed new or modified major facility in the above-mentioned counties classified as moderate nonattainment for ozone to offset the increase in VOC emissions.

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