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Indoor Inhalation

1. Indoor Inhalation Amendments

On May 16, 2013, the Illinois Pollution Control Board added the indoor inhalation exposure route to Illinois EPA’s risk-based cleanup methodology called the Tiered Approach to Corrective Action Objectives, 35 Ill. Adm. Code 742 (TACO). These  amendments are effective on July 15, 2013.The purpose of the indoor inhalation 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. This migration process is called vapor intrusion.

The indoor inhalation pathway will be managed similarly 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.

Inserting a new exposure route into TACO required comprehensive changes to the existing regulations. As would be expected, these amendments contain new definitions, equations, parameters, default remediation objectives, and mechanisms for managing the indoor inhalation exposure route.

Illinois EPA is preparing fact sheets to help cleanup program participants understand and comply with the indoor inhalation amendments. We’re also coordinating with the Illinois Environmental Regulatory Group to offer training webinars in the spring. Details will be posted here when available. In the meantime, here are answers to common questions about the proposed rule.

2. Will Illinois EPA re-open sites that have already earned a No Further Remediation letter and require them to evaluate the indoor inhalation pathway?

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

3. I have an approved remedial action plan under the existing TACO regulations. What happens if the rule takes effect before I receive the final NFR letter?

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 effective date as long as all of the information required to issue NFR is received prior to the effective date. For example, in the case of a site where a Highway Authority Agreement has been submitted to IDOT and completion report has been submitted to Illinois EPA before the July 15, 2013 effective date of the rules, indoor inhalation does not need to be addressed to be eligible for NFR.

4. What other changes do these amendments make?

Certain tables are being updated for all chemicals, not just volatile chemicals, to minimize confusion and avoid complicating the footnotes. The updated tables include the Similar-Acting Noncarcinogenic and Carcinogenic Chemicals in Appendix A, Tables E and F, and the Default Chemical and Physical Parameters in Appendix C, Table E.

This  fact sheet introduces concepts unique to the indoor inhalation exposure route and describes the specific changes being made to the Subparts and Tables.