Legislative Council reviews radon study for State House; temporary ventilators reduced levels, DAFS to pick permanent fix

The Legislative Council reviewed an architectural‑engineering report from Harriman on elevated radon levels detected on the State House first floor and options to mitigate them.

Executive Director Suzanne Gresser summarized that Harriman’s report (issued Dec. 16, 2025) lays out three tiers of remediation: restore the HVAC to design dilution rates and seal ductwork leaks (least disruptive); pull up first‑floor flooring and seal cracks communicating with the slab (more disruptive); or a combination of sealing plus dilution. Gresser said the temporary installation of energy‑recovery ventilators (ERVs) in affected rooms brought radon readings back to acceptable ranges. "They tested after the ERVs were put in, and all of the levels after they put the ERVs in were fine," Gresser said.

Gresser told council members that dilution is the baseline action any permanent plan will use and that DAFS has included funding for remediation in a spring bonding proposal. Members asked for the actual radon readings in affected rooms and whether filters and HVAC maintenance would be addressed; Gresser said tests showed elevated levels were not uniform across the first floor and that filter replacement and other mechanical maintenance are being pursued by the executive branch.

Council members pressed on timing and disruption. Gresser said DAFS will select an option and notify offices when work will occur; the ERVs are a temporary, conspicuous measure while a less intrusive long‑term solution is planned. The next steps are for DAFS to choose among the options, seek bonding funding already included in its spring request, and schedule any necessary construction.

The council accepted the report and asked staff to keep members informed about specific remediation choices and timings.