IL HB3505

Lowers the threshold for "nonnegligible ethylene oxide emissions source" from 150 pounds to 30 pounds of ethylene oxide emissions, significantly expanding which facilities are subject to regulation

Removes exemptions that previously excluded ethylene oxide sterilization sources and hospitals licensed under the Hospital Licensing Act or University of Illinois Hospital Act from the definition

Requires owners/operators of nonnegligible ethylene oxide emissions sources to submit an Ambient Air Monitoring Plan to the Illinois EPA within 180 days of the act's effective date

Ambient Air Monitoring Plans must include quarterly air sampling using EPA Methods 325A and 325B at property boundaries and community locations with highest modeled impact, conducted by independent third-party companies

Owners/operators must respond to Agency conditions or deficiencies within 3 business days and implement approved monitoring plans according to their terms