Illinois has amended its risk based cleanup rule to include the indoor inhalation or, “vapor intrusion”, exposure route. The amendments to the Tiered Approach to Corrective Action Objectives, 35 Ill. Adm. Code 742 (TACO), through a rulemaking at the Illinois Pollution Control Board, became effective on July 15, 2013. The stated purpose of the amendments is to minimize the exposure of building occupants to volatile chemicals that have the potential to migrate from the soil and groundwater to indoor air, a process known as “vapor intrusion”.

According to the Illinois Environmental Protection Agency (“IEPA”) which will issue fact sheets to explain the amendments, the indoor inhalation pathway will be managed similar to the existing exposure routes under TACO. It follows the basic framework of TACO’s three tiers, includes calculations for both residential and industrial/commercial remediation objectives, and allows for pathway exclusion, including the use of building control technologies to prevent or minimize human exposures to contamination.

A FAQs section on IEPA’s website states the following:

Q. Will Illinois EPA re-open sites that have already earned a No Further Remediation (“NFR”) letter and require them to evaluate the indoor inhalation pathway?

A. No. Illinois EPA would take action only if new site-specific information indicates a vapor intrusion problem.

Q. I have an approved remedial action plan under the existing TACO regulations. What happens if the rule takes effect before I receive the final No Further Remediation (“NFR “) letter?

A. You will be required to evaluate the indoor inhalation exposure route in accordance with the amendments. Please note that the NFR letter does not need to be issued prior to the effective date as long as all of the information required to issue the NFR is received prior to the effective date.

Illinois’ action in regulating vapor intrusion as an exposure pathway follows similar moves by other states and by the U.S. EPA with the issuance of its “final” guidance on vapor intrusion, illustrating the high priority that this exposure route is now being given by regulatory authorities at contaminated sites.