No single federal agency regulates indoor air quality in the United States. Unlike outdoor air, which the EPA controls under the Clean Air Act, indoor air falls into a regulatory gap where responsibility is split across multiple agencies, state governments, and voluntary industry standards. The result is a patchwork system where the rules depend on what kind of building you’re in and what state you live in.
Why the EPA Doesn’t Regulate Indoor Air
The EPA sets enforceable limits on outdoor air pollutants under the Clean Air Act, but its authority stops at the building door. The agency states plainly on its website: “EPA does not regulate indoor air, but we do offer assistance in protecting your indoor air quality.” That assistance comes in the form of guidelines, educational materials, and tools like the Indoor Air Quality Action Kit for schools. None of it carries the force of law.
This matters because Americans spend roughly 90% of their time indoors, where concentrations of some pollutants can be two to five times higher than outdoor levels. Despite that, Congress has never given any federal agency broad authority to set mandatory indoor air standards for homes, offices, or most public buildings.
OSHA’s Role in Workplaces
The closest thing to federal indoor air regulation applies to workplaces, and it’s limited. The Occupational Safety and Health Administration does not have a dedicated indoor air quality standard. It does, however, set permissible exposure limits for specific airborne chemicals like formaldehyde and volatile organic compounds (VOCs), and it has ventilation requirements for certain work environments.
When indoor air problems arise in a workplace that don’t fall under a specific OSHA standard, the agency can still act through the General Duty Clause. This provision of the law that created OSHA requires employers to provide a workplace free from known hazards that could cause death or serious injury. In practice, OSHA uses this clause to address severe air quality complaints, but it’s a reactive tool rather than a proactive standard. OSHA also publishes letters of interpretation that clarify how existing rules apply to indoor air situations, which give employers guidance without creating new enforceable requirements.
ASHRAE Sets the Industry Benchmark
The standards that most directly shape the air you breathe indoors come from ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers), a professional organization with no regulatory power of its own. ASHRAE publishes two key ventilation standards that have served as the industry benchmark since 1973.
Standard 62.1 covers commercial and institutional buildings. It specifies minimum ventilation rates, filtration requirements, air cleaning systems, and building maintenance practices for spaces like offices, hospitals, and schools. The 2025 edition added new humidity control requirements, ventilation system emergency controls, and updated methods for calculating exhaust airflow rates.
Standard 62.2 covers residential buildings. It sets minimum requirements for dwelling-unit ventilation, local exhaust (like bathroom and kitchen fans), and source control. A significant change in the 2025 edition raised the minimum filtration level from MERV 6 to MERV 11, a meaningful upgrade in a filter’s ability to capture fine particles. The new edition also added ozone requirements for air-cleaning devices and an informative appendix on managing infectious aerosols.
These standards become enforceable only when state or local building codes adopt them. Many jurisdictions do reference ASHRAE 62.1 in their commercial building codes, which means the standard effectively becomes law for new construction and major renovations in those areas. But compliance in existing buildings often goes unchecked.
State and Local Governments Fill the Gaps
Because federal regulation is so limited, states have become the primary source of enforceable indoor air quality rules, and coverage varies dramatically by location.
California has been the most aggressive. The California Air Resources Board (CARB) requires all indoor air cleaners sold in or shipped to the state to meet ozone emission limits of no more than 0.05 parts per million. Devices must be CARB-certified and labeled accordingly. California also regulates formaldehyde emissions from composite wood products, a standard that eventually influenced a federal rule covering the rest of the country.
For schools, many states have enacted some form of indoor air quality legislation. According to EPA tracking data, states including Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, Florida, and Georgia (along with Washington, D.C.) have statutes addressing indoor air quality in schools. But the EPA notes that “there is no statute that encompasses all facets of indoor air quality safety in schools” in any state. Some require inspections, others mandate carbon dioxide monitoring or reporting, and many simply encourage voluntary guidelines.
Radon: A Case Study in Fragmented Oversight
Radon illustrates how indoor air hazards get managed without a clear regulatory home. This naturally occurring radioactive gas is the second leading cause of lung cancer in the United States, and it seeps into buildings through cracks in foundations. Yet there is no federal law requiring radon testing or mitigation in homes.
The EPA recommends that all homes be tested and sets an action level of 4 picocuries per liter, but this is guidance, not regulation. The federal government’s most direct involvement comes through housing policy. The Department of Housing and Urban Development requires mortgage lenders to provide prospective homebuyers with a form that includes information about radon testing and references the EPA’s recommendation. Radon mitigation can also be financed through FHA 203(k) rehabilitation loans.
Beyond that, rules depend on your state. Some states require radon testing during real estate transactions. Others mandate radon-resistant construction techniques in new homes built in high-risk zones. Many states have no requirements at all.
Proposed Federal Legislation
Congress has periodically considered broader federal involvement. The Indoor Air Quality and Healthy Schools Act of 2024, introduced in the 118th Congress, would direct the EPA administrator to carry out a program supporting the assessment and reduction of indoor air contaminant exposure. It would also require the EPA to commission a National Academy of Sciences study on the feasibility of developing a science-based indoor air quality index, similar to the outdoor Air Quality Index that already informs public health warnings. As of its introduction, the bill had not been enacted into law.
Previous indoor air quality bills have followed a similar pattern: introduced, discussed in committee, and allowed to expire without a vote. The lack of a single regulatory framework means that for now, the quality of air inside your home, office, or child’s school depends largely on where you live, what kind of building you’re in, and whether local authorities have chosen to adopt and enforce voluntary standards.