Most people know that cars, trucks, and buses from our highways and city streets are a significant source of air pollution. While pollution from transportation impacts all communities in the region to some degree, the people who face the greatest exposure to transportation pollution are those who live near highways, along major freight corridors, and in urban areas.
To help understand exactly which communities bear the greatest burden and breathe the highest concentrations of this dangerous air pollution, we used a computer model to estimate the amount of fine particulate matter air pollution (known as PM2.5) created by on-road vehicles that burn gasoline and diesel. The findings, which are not likely not to be a surprise to many residents, are quite troubling: they show that people of color disproportionately breathe dirtier air than white people do:
- On average, Latino, Asian American and African American residents are exposed to more PM5 pollution from cars, trucks, and buses than white residents of the region. These groups are exposed to PM2.5 pollution 75, 73, and 61 percent higher, respectively, than white residents.
- Almost one-fifth of the region’s 72 million people live in census tracts where PM5 pollution levels are more than one-and-a-half times the average of the state where they live; more than 60 percent of the residents of those tracts are people of color.
What is PM2.5 and why is it important?
The science is clear: no level of particulate matter is safe to breathe, says the American Lung Association. While fine particulate matter – referred to as PM2.5 – is not the only air pollutant that adversely affects health, it is estimated to be responsible for approximately 95 percent of the global public health impacts from air pollution. Breathing PM2.5 is linked to increased illness and death, primarily from heart and lung diseases.
These minuscule particles are only visible to the naked eye when their concentration in the air is high, such as when a truck belches black smoke. They include particles smaller than 2.5 millionths of a meter in diameter – at least 20 times smaller than the diameter of fine human hair— so they can penetrate deep into the lungs. The ultrafine particles – smaller than 0.1 millionths of a meter – are particularly dangerous, as some can enter into the bloodstream.
Chronic exposure to PM2.5 causes increased death rates attributed to cardiovascular diseases, including heart attacks and strokes, and has been linked to other adverse impacts such as lung cancer, reproductive and developmental harm and even diabetes and dementia. Chronic exposure to PM2.5 in children has also been linked to slowed lung-function growth and development of asthma.
PM2.5 is formed in many ways. A significant source of PM2.5 is fuel combustion. The combustion engines of cars burn gasoline and diesel. Power plants burn natural gas and other fuels to produce electricity. Burning wood for cooking and in residential fireplaces, as well as wildfires, are some examples of biofuel combustion. To make things worse, not only does burning fossil fuels and biofuels produce PM2.5 directly, but the combustion reaction also emits gases such as nitrogen oxides, sulfur dioxide and volatile organic compounds that go on to form additional PM2.5 through complex chemical reactions in the atmosphere.
Because there are so many ways in which particulate matter is formed, you may ask yourself if some pose more health risks than others. Indeed particles can bind with bacteria, pollen, heavy metals, elemental carbon, dust and other building blocks, and so have a broad range of effects on human health. But size is one of the most important factors, and PM2.5 is responsible for a very heavy burden of disease, disability and death.
Greater pollution for people of color
We estimated exposure to PM2.5 pollution using a recently developed model from the University of Washington and data from the US Census Bureau. This model allows us to calculate how vehicle tailpipe and refueling emissions ultimately lead to ground-level pollution exposure, so we can understand how exposure to PM2.5 varies among groups and locations.
The results are clear: PM2.5 pollution burden from cars, trucks, and buses is inequitable when looking at the exposure experienced by racial and ethnic groups in the region. Looking at the region as a whole, Latino residents are exposed to 42 percent higher PM2.5 concentrations than a person breathing polluted air equivalent to the state’s average PM2.5. Asian Americans and African Americans experience concentrations 42 percent and 40 percent higher, respectively, than the average resident (Figure 1). At the same time, white residents have an average exposure that is 19 percent lower than the average for the region. This means that, on average, Latino, Asian American and African Americans are exposed to more PM2.5 pollution 75, 73 and 61 percent higher, respectively, than white residents.
Figure 1. Disproportionately High Exposure for People of Color in the Northeast and Mid-Atlantic Note: This analysis uses the following US Census Bureau–defined racial groups: White; Black or African American; American Indian or Alaska Native; Asian; Native Hawaiian or Other Pacific Islander; Hispanic; Latino; and Some Other Race. In the chart above, Latino includes census respondents who select Hispanic, Latino, or both; Other Race includes respondents who select Some Other Race as their only race.
When we zoom in to the census tract level, defined as an area with approximately 4,000 people, pollution inequity is just as evident as the inequity we see at the regional level (Figure 2). In census tracts with low pollution and cleaner air (where average annual PM2.5 concentrations are less than half of the state average), whites make up 85 percent of the total population, although they constitute less than two-thirds of the total population in the Northeast and Mid-Atlantic. In contrast, more people of color live in census tracts where pollution is more than one and a half times the state average. In these areas, people of color constitute slightly more than 60 percent of the population, compared with about 35 percent of the regional population.
Figure 2. PM2.5 Unequal Exposure in Different Pollution Areas. Note: Each column refers to census tracts in areas with similar PM2.5 pollution concentrations. The columns show the fraction of people belonging to each of eight racial groups living in those areas. The least polluted areas are on the left and the most polluted on the right. The 0–50% area refers to census tracts where PM2.5 pollution is less than half the regional average, the 50–100% area refers to tracts where pollution is from half the regional average to the regional average, etc. The column at the far right shows the region’s racial composition.
We were also curious about the inequities in air pollution relative to income distribution, and found that exposure inequities are more pronounced between racial and ethnic groups than between income groups. Disparities based on income are not significant because the fractions of people in each income bracket are distributed fairly evenly over areas with different pollution levels.
Pollution also varies across the region
Of all the states in the region, New York ranks highest in the region in average PM2.5 concentration from on-road vehicles, followed by Maryland, Delaware and New Jersey, all of which have averages higher than the regional average. Pennsylvania holds a close fifth place (Figure 3).
Figure 3. PM2.5 Exposure Varies Greatly across the Northeast and Mid-Atlantic. Note: Metropolitan areas in the District of Columbia, Maryland, New Jersey, New York, Pennsylvania, and Rhode Island have many areas with PM2.5 pollution at least twice as high as the regional average. There is much variability between exposure in urban and rural areas of all states.
But averages can be deceptive, and so looking at the range of PM2.5 concentrations within each state paints a clearer picture. Even if a state average is low, pockets of racial and ethnic inequity pop up frequently in the analysis, showing that very high concentrations may afflict some areas, many of which are located near junctions of major highways.
For example, New York State has the census tracts with the highest PM2.5 concentrations in the entire region. These tracts are in the Bronx, Queens, and Manhattan. The Philadelphia area also has very high PM2.5 concentrations compared with the Pennsylvania average: pollution in the state’s dirtiest census tracts is more than three times as high as Pennsylvania’s average. On the other hand, Washington, DC, has a higher average than New York State’s because it is urban – but the most polluted air in the District of Columbia is only about two-thirds the concentration of the most polluted areas in New York State.
New Jersey, New York, and Pennsylvania, the region’s three most populous states with a total of 41.4 million people, have higher PM2.5 averages than the other states. In other words, almost 58 percent of the region’s population live in states where the average pollution from on-road vehicles ranges from 94 percent to almost 150 percent of the regional PM2.5 average.
In New York State, one-third of the population experiences PM2.5 pollution levels that are more than 150 percent of the state average. Because New York is the region’s most populous state, this higher level of pollution affects 6.3 million people, almost 70 percent of whom are people of color. The most polluted census tract in New York State is in Morris Heights in the West Bronx, at the juncture of interstates 95 and 87. This neighborhood is 70 percent Latino and 29 percent African American – and only 0.2% are white.
In Pennsylvania, while the state is 78 percent white, the areas where this pollution is less than half the state average are 93 percent white; the areas where it’s more than twice the state average are only 42 percent white. Even though the state’s average pollution level is slightly lower than the average for the entire Northeast and Mid-Atlantic region, the state has the second most polluted census tract in the region, just below the pollution level of the worst census tract in the region, in the West Bronx of New York City.
Massachusetts is another state where the state average can be deceptive. Residents of Suffolk County, where Boston is located, experience pollution levels that are almost twice as high as the Massachusetts average. In the two most polluted census tracts in the state, which are in downtown Boston, encompassing Chinatown, inequity is blatant: 70% of the population consists of people of color.
There are many such pockets of inequity throughout the region.
What is to be done?
Clearly air pollution from on-road transportation such as diesel and gasoline vehicles places significant, inequitable and unacceptable health burdens on residents of the Northeast and Mid-Atlantic. This inequity reflects decades of local, state, regional, and national decisions about transportation, housing, and land use. Decisions concerning where to construct highways, where to invest in public transportation, and where to build housing have all contributed to a transportation system that concentrates emissions in communities of color. In many cases, transportation policies have left those communities with inadequate access to public transportation, divided by highways, and exposed to air polluted by congested highways serving suburban commuters.
We have the tools and the technologies to transform our transportation system away from diesel and gasoline and toward clean, modern, equitable solutions. With targeted actions in electrification and clean fuels, the region can save more than $30 billion by 2050 and save thousands of lives.
Electrification of vehicles, both passenger and freight, could greatly reduce emissions. Battery-electric and fuel cell vehicles have no tailpipe emissions, with the exception of minor amounts of PM2.5 emissions from tire and brake wear. Not just that, but these vehicles eliminate emissions associated with refueling. The electricity used to charge the vehicle can produce some emissions from electricity generation, but it’s critical to remember that these emissions are lower than those of an average gasoline car, even if it charges in coal country, and emissions vary depending on the location where the vehicle is charged. In the Northeast and Mid-Atlantic, the Regional Greenhouse Gas Initiative, along with investments in solar, wind, and other renewable electricity resources, has greatly reduced emissions from electricity generation.
Significant new funding is necessary to expand access to clean transportation in these communities, as are strong regulations that limit transportation emissions and put a price on carbon pollution. And the communities most affected by transportation pollution often have the fewest available resources.
In December 2018, nine states in the region and the District of Columbia agreed to create a regional, market-based program that would limit transportation emissions and invest in clean transportation. They plan to use funds raised from pollution permits to make strategic investments in clean transportation. States should seek input from communities disproportionately burdened by transportation pollution and ensure that equity is a key consideration in both design processes and future investment decisions.
Specific investments that could reduce inequities include:
- Investments in electric transit and school buses, with a priority on serving communities exposed to the highest levels of gasoline and diesel emissions
- Expansion of electric vehicle rebate programs to provide financing assistance and larger rebates to low- and moderate-income residents
- Utility investments in electric vehicle charging infrastructure, with a priority on serving communities exposed to the highest levels of gasoline and diesel emissions
- State programs that provide aid to municipalities to support clean transportation, with a priority on serving communities exposed to the highest levels of pollution.
- While residents of the region can make a difference by choosing cleaner vehicles and driving less, much of today’s air pollution comes from sources outside the direct control of individuals. States need regulations, incentives, and other policies to reduce vehicle emissions, with equity and the meaningful involvement of affected communities as key considerations in designing policies and strategies to reduce pollution from vehicles.
States need to continue to reduce emissions, placing a high priority on actions that reduce the inequitably distributed burden of air pollution in the Northeast and Mid-Atlantic. This analysis provides important quantitative evidence of the need for and importance of such programs, and it can help inform and shape future actions to reduce pollution exposure and environmental inequities in the region.