Reducing Indoor Exposure to Particle Pollution from Outdoor Sources Policies and Programs for Improving Air Quality in Homes JANUARY 2020 The Environmental Law Institute gratefully acknowledges the assistance of many individuals who provided information for this report and reviewed earlier drafts. Funding for the report was provided by the U.S. Environmental Protection Agency. The contents of the report are the responsibility of ELI. The views expressed herein should not be attributed to EPA, nor should any official endorsement be inferred. The Environmental Law Institute (ELI) makes law work for people, places, and the planet. Since 1969, ELI has played a pivotal role in shaping the fields of environmental law, policy, and management, domestically and abroad. Today, in our fifth decade, we are an internationally recognized, nonpartisan research and education center working to strengthen environmental protection by improving law and governance worldwide. Reducing Indoor Exposure to Particle Pollution from Outdoor Sources: Policies and Programs for Improving Air Quality in Homes © 2020 Environmental Law Institute®, Washington, D.C. All rights reserved. Cover Photos: Manfredxy, Chuangz, ssuaphotos, Thomas Oswald/Shutterstock.com Contents Executive Summary .................................................................................................................................. i Chapter One: Introduction ....................................................................................................................... 1 Health Effects of Particulate Matter ............................................................................................. 2 Ambient Particulate Matter in the United States .......................................................................... 5 Reducing Indoor Exposure to Particulate Matter from Outdoor Sources ...................................... 7 Scope and Organization of the Report .......................................................................................... 8 Chapter Two: Reducing Exposure to Outdoor Particulate Matter in New Homes .................................... 10 Part I: Strengthening Standards for New Residential Construction ..................................................... 10 High-Efficiency Filtration and Related Building Practices to Reduce Indoor Exposures ................ 11 Building Codes: Strengthening Minimum Residential Construction Requirements ...................... 15 Green Building Codes: Going Beyond Minimum to Reduce Indoor PM Exposures ....................... 25 Requirements for Publicly-Funded Residential Construction ...................................................... 29 Discussion .................................................................................................................................. 31 Part II: Addressing Local PM Sources and New Residential Construction: High-Volume Roads ........... 34 Near-Road Exposures: Nature and Extent of the Problem .......................................................... 35 Practices for Reducing Near-Road Exposures in New Homes ...................................................... 37 Policies for Reducing Near-Road Exposures in New Homes ........................................................ 40 Discussion .................................................................................................................................. 48 Chapter Three: Reducing Exposure to Outdoor Particulate Matter in Existing Homes ............................. 50 Part I: High-Efficiency Filtration and Other Measures for Reducing Exposures in Existing Homes ....... 51 High-Efficiency Filtration in Existing Homes ................................................................................ 51 Filtration and other Practices for Reducing Indoor Exposures during Wildfire Smoke Events ...... 53 Discussion .................................................................................................................................. 56 Part II: Strengthening Policies for Reducing Exposures in Existing Homes .......................................... 58 Housing Codes: Strengthening Minimum Property Maintenance Standards ............................... 59 Landlord-Tenant Laws ................................................................................................................ 63 Other Laws Addressing Indoor Environmental Conditions in Existing Homes .............................. 64 Discussion .................................................................................................................................. 65 Part III: Providing Funding for Reducing Exposures in Existing Homes ................................................ 70 Funding for Energy Retrofits and Housing Repairs ...................................................................... 70 Funding to Reduce Wildfire Smoke Exposures ............................................................................ 78 Discussion .................................................................................................................................. 83 Executive Summary Particle Pollution is an Important Public Health Issue in the United States Communities throughout the United States are affected by ambient air pollution from a variety of sources, including industrial facilities and power plants, cars and trucks, wildfires, and residential wood burning. One of the most significant air pollutants in terms of health risks is particulate matter (PM) – a mixture of small, solid particles and liquid droplets that may be emitted from a source directly or formed in the atmosphere as a result of complex reactions of other chemicals. Once inhaled, some of these particles can pass the nasal defenses, penetrate deep into the lungs, and even enter the bloodstream. The health effects from exposure to particulate matter – especially fine particles, or PM2.5 – have been studied for years, and scientific evidence of the risks continues to mount. Exposure to particle pollution is associated with a range of respiratory and cardiovascular symptoms and diseases, as well as premature death. Older adults, children, and people with heart or lung diseases are especially vulnerable to the harmful effects of breathing particulate matter. The U.S. has achieved substantial progress in reducing ambient air pollution over the past several decades, thanks in large measure to passage and implementation of the federal Clean Air Act. Nonetheless, research has found that harmful health effects can occur at PM levels below the limits set by federal law, and no threshold value has been identified. Moreover, many communities are impacted by pollution from local sources, such as high-volume roads, which may not be reflected in state and local air monitoring. While areas throughout the country are affected by particle pollution, studies have documented disproportionate air pollution exposures in communities of color and low-income communities. A key to improving public health and mitigating climate change is to reduce air pollution at the source, e.g., by transitioning to cleaner power and cleaner vehicles. In the meantime, millions of people will continue to be at risk of serious health effects from particle pollution. As we work toward a future of greatly reduced emissions, action is needed now to minimize exposures. The large majority of PM exposures in the U.S. occur indoors, where people spend most of their time. States, tribes, and local governments have an important role to play in advancing building design, construction, operation, and maintenance practices that reduce indoor exposure to outdoor particle pollution. This report highlights opportunities for developing policies and programs that can help improve public health and increase the resilience and adaptive capacity of individuals and buildings in the years ahead. Well-Established Building Practices can Reduce Indoor Exposure to Outdoor Particle Pollution Particles in outdoor air enter buildings through cracks and gaps in the building envelope and through natural or mechanical ventilation. Fortunately, building science provides solutions that can help reduce indoor exposure to outdoor pollutants by: Reducing infiltration of outdoor air – e.g., through sealing of the building envelope, important for reducing entry of outdoor pollutants and also a central strategy for improving energy efficiency; i Environmental Law Institute Providing adequate outside air for ventilation – important for avoiding the buildup of pollutants from indoor sources that can occur with a tight building envelope; and Ensuring adequate air filtration – important for filtering pollutants when outside air is brought in through ventilation systems and when air recirculates within the building. Building design and construction practices for applying these principles to reduce indoor PM exposures are well established and readily available. In particular, there is now broad consensus among building science experts that high-efficiency filtration can be very effective at removing particles indoors. New and renovated mechanical systems can be designed to accommodate high-efficiency filters, facilitate regular filter replacement, and run efficiently to help minimize the cost of operating the system. Existing homes vary widely in the protection they provide against outdoor particle pollution. In situations where it is not possible to provide higher-efficiency filters in a home’s mechanical system, portable air