Addressing the Hazards of Particle Pollution Where Most Exposures Take Place—Indoors

Wednesday, February 19, 2020
Tobie Bernstein

Senior Attorney; Director, Indoor Environments and Green Buildings Program

Last month, new regulations took effect in California to address one of the most serious public health risks in the United States and around the world—particle pollution. The new regulations do not address vehicles, power plants, or other sources of pollution. Instead, they aim to reduce exposure to particle pollution where it occurs most—inside buildings. Particles in outdoor air enter buildings through cracks and gaps in the building and through natural or mechanical ventilation. Under California’s 2019 Energy Code, new homes and other buildings throughout the state are now required to be equipped with high-efficiency air filtration, a well-established technology that can be effective in reducing indoor levels of particulate matter but has yet to be incorporated broadly into building codes.

The groundbreaking California regulations are discussed in a new report from ELI: Reducing Indoor Exposure to Particle Pollution From Outdoor Sources: Policies and Programs to Improve Air Quality in Homes. The report discusses policy and program opportunities for reducing the level of particulate matter inside residential buildings and highlights some of the strategies that have been used to tackle the issue in schools. A key to improving public health and mitigating climate change is to reduce air pollution at the source, for example, by transitioning to cleaner power and cleaner vehicles. In the meantime, people continue to be at risk from particle pollution. As we work toward mitigating emissions now and into the future, action is urgently needed to minimize exposures.

Decades of public health research have documented the health effects associated with particulate matter, especially fine particles (PM2.5), which are responsible for a range of respiratory, cardiovascular, and neurological impacts. Tens, if not hundreds, of thousands of people in the United States die prematurely from exposure to this pollutant, primarily from cardiovascular disease. Those who are most vulnerable include older adults, children, and those with preexisting heart and lung conditions.

Research has shown that harmful health effects can occur at PM levels below the limits set by federal law, and no safe level has been identified. Thus, while California dominates the list of areas that are out of attainment with federal PM standards, communities throughout the country still experience levels of particle pollution that put people at risk. Furthermore, studies have documented disproportionate air pollution exposures in communities of color and low-income communities. Some of these risks come from local sources, such as high-volume roads, which may not be reflected in state and local air monitoring.

Most U.S. communities are covered by a residential building code and have an opportunity during their next code revision process to consider California’s approach to reducing PM exposures and improving the resilience of new homes and other buildings. In the absence of a building code requirement that applies to all new residential construction, policymakers could develop guidelines for ensuring that high-efficiency filtration and other green building elements are included in government-funded construction projects such as affordable housing and schools. Local governments can also craft health, building, and land use policies that include measures to reduce PM exposures in new homes proposed to be built near high-volume roadways or other local pollution sources.

While strengthening standards for new construction is important, newly built and renovated homes represent only a fraction of the U.S. housing stock. Strategies for addressing PM exposures in existing homes involve similar technical practices, but raise different practical challenges. One challenge is a lack of information on the part of building owners and residents about when and how to take steps to reduce their exposure. Another is the cost of obtaining and operating the necessary equipment. Thus, a combination of regulatory mechanisms (such as property maintenance codes) and financial assistance and outreach programs is needed to protect vulnerable groups and those who are not in a position to take recommended actions for reducing their exposure. State, tribal, and local policies and programs can be designed to reduce indoor PM exposures broadly or they can be targeted toward addressing a particular source of concern, such as roadway pollution, wood burning, or wildfire smoke.

Although ELI’s new report is focused on particulate matter generated outdoors, people are also exposed to particles emitted indoors. Policy and program strategies tailored to specific indoor sources—e.g., enhanced exhaust ventilation in kitchens or requirements for wood-burning devices—are also important and will be addressed in future ELI reports.

Read the new report: Reducing Indoor Exposure to Particle Pollution From Outdoor Sources: Policies and Programs to Improve Air Quality in Homes.

To browse ELI’s other policy materials on indoor environmental quality, visit