The air we breathe indoors can potentially hold invisible, unchecked threats to our health, our wallets and the climate. Indoor air is often more polluted than outdoor air, even more so in buildings that burn fossil fuels. Greenhouse gas emissions from combustion fuels are causing more severe and frequent extreme weather conditions, which may further degrade indoor air quality (IAQ) and introduce new problems to households and businesses, according to the U.S. Environmental Protection Agency.
Despite these risks, IAQ is ill-defined and largely unregulated by federal and most state governments. Adopting IAQ guidelines and policy can transform health-protective strategies in the building sector that also help move the needle on climate change, including the uptake of well-sequenced, health-conscious building electrification.
Today’s Buildings Fall Short on Protecting Health
We spend most of our time indoors. According to the EPA, indoor pollutant levels are often five times higher than outdoor levels. Associated health effects can range from mild irritation to serious chronic illness, in addition to reduced worker productivity and focus. Combustion-fuel use can lead to even more indoor and outdoor pollution; onsite fossil-fuel use in buildings accounts for roughly 10 percent of U.S. greenhouse-gas emissions. Studies show that air in homes with gas stoves can have 50 percent more fine particulate matter and 50 to 400 percent more lung-damaging nitrogen dioxide than homes with electric stoves. Even when properly maintained, research shows that gas stoves can release pollutants associated with cancer and other life-threatening illnesses, including carbon monoxide, formaldehyde, and benzene.
IAQ is ill-defined and largely unregulated by federal and most state governments.
The health risks of indoor pollution are worse for vulnerable populations. Children, the elderly, and those with existing respiratory conditions spend more time indoors and may have higher sensitivity to pollutant exposure. Low socioeconomic households and People of Color face structural and institutional factors that sustain health disparities. In addition to disproportionate health burdens, these communities may live in housing conditions that are smaller, more crowded, older and closer to sources of outdoor pollution.
As IAQ-protective policy is limited, voluntary standards and certification programs from third-party professional organizations currently offer the most expansive IAQ management strategies. However, many reference outdoor air benchmarks that are often less protective of health. Current ventilation standards—ANSI/ASHRAE Standards 62.1 and 62.2—set a low bar by aiming to achieve minimum acceptable IAQ, rather than a health-protective standard. These standards and programs are not required unless adopted by a standard-setting authority. Further, current controls for sources of indoor pollution are not uniformly enforced. For instance, many state building codes do not require range hoods for gas stoves, despite their impact on indoor pollution.
IAQ Guidance: Untapped Benefits
Indoor spaces hold massive potential. Avoidable costs of indoor air pollution are estimated by EPA at well over $100 billion annually, including avoidable deaths from radon and tobacco smoke exposure, productivity losses for businesses and avoidable respiratory illnesses. During the past half-century, the Clean Air Act has cleared 78 percent of outdoor air pollutants with health savings exceeding costs by a ratio of 30 to one. A similar indoor air policy that reduces indoor pollutants could prevent respiratory illness cases, emergency-room visits, school and work absences, and deaths—translating to health savings and lower carbon emissions.
Additionally, considering IAQ in building electrification, design, and upgrades can improve performance and minimize health risks. Properly addressing indoor pollutant sources before tightening the building’s envelope can avoid unintended health consequences. Further, pairing electrification with high-efficiency ventilation and filters can save energy, reduce emissions and benefit health. Research modeling weatherization found that tightening the building envelope in isolation increased serious asthma events by 20 percent, but eliminating indoor sources of pollution and repairing ventilation hoods mitigated this effect. Electrifying the gas stove resulted in the highest health cost savings.
Next Steps to Improve Indoor Air Guidance and Policy
The past year has had the most hazardous air-quality days of the last 25 years, made worse by climate change, according to the American Lung Association’s 2024 State of the Air report.
Policymakers, builders, operators and owners need more guidance. Guidelines that include pollutant-level benchmarks are a foundational step that set the ground rules for healthy indoor spaces. Federal agencies, such as EPA, and state agencies, such as health departments and air agencies, can set voluntary guidelines. These aren’t a new concept; more than 50 organizations across 38 countries have established guidelines.
Application of IAQ guidelines will require action from policymakers, public-health professionals, building industry members, researchers and the public. Although guidelines are voluntary, they can inform a variety of building practices and policies:
- Building protocols, such as proactive building inspections or building upgrades, can assess and mitigate indoor air pollution based on guideline limits.
- Product safety agencies can also refer to guidelines to assess pollution from appliances and other indoor products, which may provide more health-protective decisions for consumers.
- Voluntary building programs, such as certifications and ventilation standards, can set health-based ventilation requirements and control or remove pollutant sources based on guidelines. Additionally, these programs can incentivize decarbonization and electrification to further limit indoor pollution.
- Regulatory policy can set mandatory limits on indoor air pollutants based on guidelines through building codes, standards or other policies authorizing indoor air management.
- Guidelines can also act as an informational resource for decision-makers. Policymakers can refer to existing guidelines globally to set federal or state guidelines and other IAQ policies. Guidelines can be used to inform risk-management strategies. Additional decision-makers may include health professionals, building operators and consumers.
Now is the Time to Double Down on IAQ
The desire for indoor air guidance is growing, as is the urgency. The past year has had the most hazardous air-quality days of the last 25 years, made worse by climate change, according to the American Lung Association’s 2024 State of the Air report.
Meanwhile, indoor air experts have drafted indoor air policy, called for IAQ standards and convened public knowledge-sharing events. Cities and states have taken strides to advance existing IAQ guidelines and propose new indoor air policies. Although indoor air management is complex, guidelines can set a uniform baseline for addressing health-harming pollutants and provide valuable direction for the market.
To further explore the ways that guidelines can inform healthy buildings and read recommended next steps for policymakers, access the full report from RMI and webinar recording with IAQ experts.
