Communities throughout the United States are experiencing a variety of conditions associated with a changing climate—hotter summers and heat waves, droughts, intense storms and flooding, increased average precipitation and humidity, and more severe wildfires. Alongside potentially far-reaching environmental and economic impacts, these conditions have direct and indirect effects on human health. In recent years, scientists have begun to shed light on important climate-related health effects that occur indoors, where people spend the vast majority of their time.
Indoor air quality (IAQ) is affected by an array of complex interactions. Outdoor conditions such as air pollution, humidity, and precipitation influence the indoor environment, depending on factors such as the building envelope, mechanical ventilation systems, and occupant behaviors. Pollutants can also be generated indoors by sources and activities such as cooking, smoking, cleaning, fuel-burning combustion appliances, and chemicals emitted from building materials, furnishings, and household and personal care products. According to the U.S. EPA, indoor levels of pollutants may be two to five times higher than outdoor levels, and occasionally as much as 100 times higher. These indoor pollutant exposures are associated with a variety of health effects, from respiratory disease and symptoms to neurological impairment and cancer, and result in significant economic costs to society.
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In 2011, the Institute of Medicine at the National Academy of Sciences issued a comprehensive report summarizing the current state of the science on climate change and indoor air quality. The report describes a wide variety of IAQ issues, concluding generally that “the available research indicates that climate change may make existing indoor environmental problems worse and introduce new problems. . . .” [emphasis added]. A 2016 report on climate change and health by the U.S. Global Change Research Program also noted that “alterations in indoor air pollutant concentrations from climate change have important health implications.” Scientists from Lawrence Berkeley National Laboratory, the National Institute of Standards and Technology, and other institutions have added important research to refine our understanding of how indoor environmental quality may be affected by climate change.
States have an important role to play in protecting the public from these indoor exposures. To advance state efforts, ELI has published Indoor Air Quality in Homes: State Policies for Improving Health Now and Addressing Future Risks in a Changing Climate. Building on the recent scientific literature, the new report discusses policy strategies for addressing three residential IAQ issues that are important concerns today and may become even more significant as a result of climate change:
- Wildfire Smoke, a mixture of gases and fine particles, can aggravate heart and lung disease and is linked to premature death in people with those conditions. The United States burns twice as many acres as it did three decades ago, and the acreage burned may double again by mid-century. Western states are hardest hit, but other regions are affected as well. It is estimated that over one-half of the health effects caused by wildfire smoke will be the result of indoor exposure because the outdoor emissions enter indoor spaces.
- Dampness and Mold are already common problems throughout the country, and both conditions are associated with a range of respiratory and allergic effects. Dampness and mold problems are a result of water incursion and excess moisture in buildings, conditions that are likely to grow worse with increases in the frequency and severity of storms and increased average precipitation and humidity in some regions of the country.
- Energy Efficiency Retrofits have been an important policy strategy for reducing greenhouse gas emissions and limiting the health and other impacts of climate change in the long term. While these retrofits can help improve IAQ in a home, if precautions are not taken, energy-efficiency measures can have unintended negative consequences on indoor environmental quality by disturbing hazardous materials that may be present, introducing new contaminants through building materials or products, or reducing ventilation rates.
In each of these areas, government and industry technical guidance exists for preventing and mitigating problems, and some states have developed policies and programs to institutionalize these best practices. Nevertheless, there remains considerable room for further action. The new ELI report describes existing approaches for consideration by other jurisdictions, highlighting strategies for reaching those who are most vulnerable to the health effects of these exposures. Because these IAQ issues already present significant public health challenges, states have an opportunity to put in place policies that not only prepare for anticipated increased future risks, but also reap considerable health and economic benefits in the near term.
The full report and individual chapters can be downloaded at: https://www.eli.org/buildings/indoor-air-quality-homes.
Additional reports, policy briefs, and other materials on IAQ policy are available at: www.eli.org/buildings.