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Toward Cleaner Indoor Air: State Legislative Progress 2020-2025

Toward Cleaner Indoor Air: State Legislative Progress 2020-2025

In the past five years (2020-2025), thirteen states have enacted indoor air quality legislation, with a focus on schools and public buildings. This document provides a summary of these laws.

 

Map showing US states with legislative progress on indoor air quality, 2020-2025. Light blue dots for schools, dark blue for public buildings.

Thirteen states have enacted indoor air quality (IAQ) legislation between 2020 and 2025, with a focus on schools and public buildings. With a quarter of states advancing healthy indoor air, this signifies national momentum to bring cleaner indoor air to students and public workers. This educational and reference tool offers a snapshot of recently enacted legislation and focuses on broader IAQ measures, such as efforts to enhance ventilation and filtration. While previous IAQ policies have addressed specific pollutants such as radon, mold, and carbon monoxide, states have taken a more holistic approach to promoting healthy indoor air.

 

Key Themes Across State IAQ Legislation

  • Schools as a Priority: Most bills target K-12 schools and early learning centers, requiring ventilation assessments, compliance with ASHRAE standards, and/or regular HVAC inspections. 
  • Minimum IAQ Standards: Many states set baseline standards for IAQ, such as requiring the use of MERV-13 filters. 
  • Certified Workforce Standards: Several bills require HVAC upgrades to be completed by licensed or certified professionals. 
  • State Oversight & Transparency: Legislation often establishes a state IAQ council, mandates public reporting, and strengthens state-level coordination. 
  • Climate & Energy Integration: IAQ improvements are increasingly part of broader building decarbonization and energy efficiency plans.
BillStateYearDescription
AB 2232California2022Requires schools to meet updated ventilation and filtration standards where feasible, including MERV 13 filters and continuous CO2 monitoring in classrooms, while state agencies work to establish mandatory CO2 monitor standards.
AB 841California2020Funds public schools to assess and improve ventilation systems, requiring MERV 13 filters, CO2 monitors, and compliance with state ventilation standards, with verification reports made publicly accessible.
HB 25-1245Colorado2025Requires schools using federal or combined federal-state funds for HVAC upgrades to meet specific requirements for the installation, inspection, and maintenance of their HVAC systems.
HB 5506, Sec. 367, 368, 370Connecticut2022Establishes a $75 million HVAC grant program to reimburse school districts for projects improving IAQ and requires schools to conduct assessments using the Tools for Schools program.
SB 270Delaware2022Requires public schools to follow IAQ standards set by the Division of Public Health, including routine monitoring, contractor certification, and a formal process for receiving and investigating IAQ complaints.
HB 4903Illinois2024Tasks the State Board of Education, in partnership with the Department of Public Health, to compile and share resources for assessing air quality and maintaining school ventilation systems, with outreach to elementary and secondary schools.
LD 1407 / HP 929Maine2025Directs the Dept. of Labor to report findings from the Indoor Air Quality Advisory Group and develop IAQ standards for buildings where public employees work.
SB 173, Sec. 12a / HB 4437Michigan2023Directs the Dept. of Education to establish a $50 million healthy schools grant program to fund IAQ improvements, energy upgrades, toxin remediation, and drinking water system enhancements, with a 50% matching requirement from grantees.
HF 2310, Sec. 123B.663Minnesota2023Directs the Department of Commerce to establish a $1 million air ventilation pilot grant program, prioritizing schools. Sets requirements for eligible activities, mandated reporting, filtration rates, and workforce performing the upgrades.
AB 257Nevada2021Requires schools to assess and improve ventilation and filtration systems as funding allows, use the highest efficiency MERV filters when possible, comply with the Uniform Mechanical Code, and complete assessment and district-wide reports.
SB 3995New Jersey2021Creates the School and Small Business Energy Efficiency Stimulus Program fund at the Board of Public Utilities to upgrade HVAC systems in schools. Requires the Dept. of Health to study IAQ in public schools, identify contaminants, and recommend mitigation measures.
HB 3031Oregon2023Requires school districts using state or federal funds for HVAC upgrades to conduct ventilation verification, CO2 monitoring, HVAC assessments, and submit verification reports to the Oregon Dept. of Education.
HB 2618 / SB1413Virginia2025Requires school boards to set preventative maintenance schedules for HVAC systems and ensure IAQ through inspections every two years, with industry-recognized evaluations at least every four years.
SB 5949 / HB 2089Washington2024Appropriates $45 million for FY2024 grants to improve school IAQ and energy efficiency, with about one-third reserved for small districts. Funded projects include HVAC upgrades and air quality improvements. Requires facility assessments with cost estimates to be reported to the legislature.