How big are the exposure gaps between communities?
The disparities are large and consistent across pollutants and countries. In the United States, a national study of six major air pollutants from 1990 to 2010 found that for every pollutant, the racial/ethnic group with the highest average exposure was a minority group. The gap was largest for nitrogen dioxide (NO₂), where the most exposed group breathed 54% more (4.6 parts per billion) than the least exposed group [5]. For fine particulate matter (PM2.5), Black populations faced exposures at least 5% above the national average in 63% of US states, while no state showed above-average exposure for white populations [5].
In the greater Seattle area, the disparities are even starker for ultrafine particles (UFPs), which are especially harmful to heart and lung health. Census blocks with median household incomes below $20,000 had UFP concentrations 40% higher than the regional average, while blocks with incomes above $110,000 had levels 16% below average [3]. Black residents in Seattle breathed 15% more UFPs than the average, and Native American and Pacific Islander residents faced 8% and 11% higher exposures, respectively [3].
These patterns are not unique to the US. In India, a 2023 study found that a one-standard-deviation increase in the prevalence of Scheduled Caste households was linked to 0.13 micrograms per cubic meter (µg/m³) higher PM2.5 levels [4]. In China, however, the pattern flips: higher-income populations are exposed to more ambient air pollution, likely because they live in wealthier, more industrialized urban centers [6]. This shows that the relationship between income and pollution depends on a country's stage of development.
What are the health consequences of these disparities?
Higher pollution exposure translates directly into worse health outcomes for minority and low-income groups. A 2025 national US study found that people exposed to PM2.5 levels above 9.0 µg/m³ had a 20% higher risk of rating their own health as 'poor' [1]. The same study showed that minority and low-income populations face elevated risks for asthma, high blood pressure, diabetes, kidney disease, and mental health problems [1].
The health impacts are measurable even at the global scale. A meta-analysis of studies from low- and middle-income countries found that for every 10 µg/m³ increase in PM2.5, the risk of death from any non-accidental cause rose by 0.48% in the short term and 4.3% in the long term [2]. In China, ethnic minorities showed a 61% higher odds of developing cardiometabolic abnormalities (like obesity and high blood pressure) per 10 µg/m³ increase in PM2.5 compared to the Han majority [8].
These disparities are compounded by the fact that disadvantaged communities often have less access to healthcare and fewer resources to mitigate pollution's effects. A 2024 position statement from the American College of Preventive Medicine notes that even during COVID-19 lockdowns, when overall pollution dropped, the gap between white and non-white communities persisted [12].
What can be done to reduce these disparities?
Policy interventions can make a real difference, but they must be designed carefully. A 2022 study of US decarbonization pathways found that if no climate policies are implemented, Black and high-poverty communities could face 0.19–0.22 µg/m³ higher PM2.5 than the national average during the energy transition. However, national mandates requiring more than 80% renewable or low-carbon energy achieved equal pollution levels across all demographic groups [9].
Targeted investments also help. A 2025 study on truck electrification found that electrifying short-haul routes near ports and urban centers would bring large health benefits to disadvantaged communities, though the relative gap between disadvantaged and non-disadvantaged groups could widen if benefits aren't distributed equitably [10]. In California, adopting low-carbon fuels by 2050 could reduce racial disparities in PM2.5 exposure by up to 20% and for ultrafine particles by up to 40% [7].
Local action matters too. In Toronto, researchers used toxicity-weighted pollution data to identify neighborhoods facing a 'double burden' of poverty and high toxic air exposure, allowing city planners to prioritize pollution prevention in those areas [13]. Similarly, a 2022 study of US public housing developments found that Black, Hispanic, and extremely low-income households are disproportionately located in neighborhoods with higher PM2.5, pointing to the need for housing and environmental policies that work together [11].
Sources used in this answer
Assessing health risks and socioeconomic disparities associated with ambient air pollution and point sources across the United States
Minority and low-income US groups are exposed to higher PM2.5 and face greater risks for asthma, high blood pressure, diabetes, and kidney disease; PM2.5 above 9.0 µg/m³ raises the risk of poor self-rated health by 20%.
Meta analysis of health effects of ambient air pollution exposure in low- and middle-income countries
In low- and middle-income countries, each 10 µg/m³ increase in PM2.5 raises short-term non-accidental mortality risk by 0.48% and long-term risk by 4.3%.
Exposure Disparities by Income, Race and Ethnicity, and Historic Redlining Grade in the Greater Seattle Area for Ultrafine Particles and Other Air Pollutants
In Seattle, the poorest neighborhoods have 40% higher ultrafine particle levels than average, while Black residents face 15% higher exposures than the regional average.
An environmental justice analysis of air pollution in India
In India, a one-standard-deviation increase in Scheduled Caste prevalence is linked to 0.13 µg/m³ higher PM2.5 exposure.
Disparities in Air Pollution Exposure in the United States by Race/Ethnicity and Income, 1990–2010
In the US, racial/ethnic minorities are the most exposed group for all six major air pollutants; the NO₂ gap between the most and least exposed groups is 54%.
Ambient Air Pollution and Socioeconomic Status in China
In China, higher-SES populations are exposed to more ambient NO₂ and PM2.5 than lower-SES groups, opposite to the US pattern.
Adoption of low-carbon fuels reduces race/ethnicity disparities in air pollution exposure in California
Adopting low-carbon fuels in California by 2050 could reduce racial disparities in PM2.5 exposure by up to 20% and for ultrafine particles by up to 40%.
Ethnic disparities in the association between ambient air pollution and risk for cardiometabolic abnormalities in China
In China, ethnic minorities have 61% higher odds of cardiometabolic abnormalities per 10 µg/m³ increase in PM2.5 compared to the Han majority.
Air pollution disparities and equality assessments of US national decarbonization strategies
Without decarbonization policies, Black and high-poverty US communities could face 0.19–0.22 µg/m³ higher PM2.5; mandates for >80% renewable energy achieve equal exposure across groups.
Impact of truck electrification on air pollution disparities in the United States
Truck electrification reduces air pollution deaths in disadvantaged US communities, but the relative disparity between disadvantaged and non-disadvantaged groups may increase.
Air pollution exposure disparities in US public housing developments
US public housing developments are disproportionately located in neighborhoods with higher PM2.5, and Black, Hispanic, and extremely low-income households are most affected.
ACPM Position Statement: Air Pollution and Environmental Justice
The American College of Preventive Medicine recommends cleaner energy, more green space, and using social determinants of health codes to address air pollution disparities.
Identifying inequitable exposure to toxic air pollution in racialized and low-income neighbourhoods to support pollution prevention.
In Toronto, the proportion of visible minorities living within 2 km of the most toxic industrial facilities is 12.9% higher than near other facilities.