Nearly every source of the nation’s most pervasive and deadly air pollutant disproportionately affects Americans of color, regardless of their state or income level, according to a study published Wednesday. The analysis of fine-particle matter, which includes soot, shows how decisions made decades ago about where to build highways and industrial plants continue to harm the health of Black, Latino and Asian Americans today.

The findings of researchers from five universities, published in the online journal Science Advances, provide the most detailed evidence to date of how Americans of color have not reaped the same benefits as White Americans, even though the country has made major strides in curbing pollution from cars, trucks, factories and other sources. The particles studied have diameters of no more than 2.5 micrometers — one-thirtieth the width of a human hair — and can become embedded in the lungs. Known as particulate matter (PM) 2.5, they account for between 85,000 and 200,000 premature U.S. deaths each year.

The new paper, coupled with two other analyses also released Wednesday, bolsters the argument that environmental advocates have made for years that Black, Latino, Asian and Native Americans bear a heavier burden. And this growing body of research is showing the full scope of the problem.

Black, Hispanic and Asian Americans face a higher level of exposure than average to PM 2.5 from industry, light-duty vehicles, diesel-powered heavy trucks and construction, while Black Americans are exposed to greater-than-average concentrations from all categories in the Environmental Protection Agency National Emissions Inventory. White Americans have slightly higher-than-average exposure from agriculture and coal-fired power plants, the analysis found, because of where both are located.

“The deck is stacked against people of color, for almost every emission source,” Joshua Apte, one of the authors and an engineering professor at the University of California at Berkeley, said in an interview. “The recipe we’ve had for improving air quality for the last 50 years, which has worked well for the country overall, is not a good recipe for solving environmental inequality.”

The study found that Black people are exposed to 21 percent more fine-particle pollution compared to average Americans, while exposure was 18 percent greater for Asian Americans and 11 percent more for Hispanics. White Americans, by contrast, have 8 percent less pollution exposure than the average.

Regional differences have some impact on exposure. Latinos face lower-than-average exposure to soot from coal-fired power plants, for example, because a higher proportion of them live in the Southwest where such facilities are less concentrated.

For decades, the voices of communities of color have been the least heard within the predominantly White conservation movement. But President Biden has pledged to change that, saying he will take racial disparities into account when deciding which road projects taxpayers should fund and which power plants should be constructed.

The Trump administration repeatedly minimized the disproportionate impacts of air pollution on communities of color, according to documents obtained by The Washington Post, and last December chose not to tighten national standards for fine-particle matter. It spent much of its term seeking to either zero out or make deep cuts to the EPA’s Office of Environmental Justice, which works to evaluate and address pollution in communities of marginalized people and the sources that cause it.

At her home about a block from the Port of Oakland, where ships and diesel trucks belch particle matter round-the-clock, California activist Margaret Gordon believes that government and corporations long placed pollution sources near non-White communities by design.

The finding that Black people suffer more from freeway pollution is something “we’ve been living and looking at … for years,” she said. The evidence is found in the crevices of people’s ceilings, she added. “It’s not dirt; it’s particulates.”

Using a high-resolution air-modeling tool, the new analysis shows that myriad polluters account for why Americans of color tend to breathe dirtier air regardless of whether they live in rural or urban areas or earn more or less income.

Cinthia Moore, EcoMadres national lead of the Moms Clean Air Force, lives in a heavily Latino neighborhood in east Las Vegas that is near major roadways and a freeway. Construction seems constant. “There’s just heavy vehicles 24-7,” she said.

Since she and her young son moved there two years ago from the wealthier suburb of Summerlin, both have suffered respiratory issues. While air purifiers work well enough indoors, Moore said, “as soon as he’s outside, he breaks out into rashes and has trouble breathing.”

Christopher Tessum, the paper’s lead author and a professor of civil and environmental engineering at the University of Illinois at Urbana-Champaign, said Monday that it will take a sweeping set of policies to address the disparities: “It’s not like there’s one type of magic bullet.”

Systematic bias extends even to what sort of natural defenses these communities have against a warming climate, according to a separate study published Wednesday, which found that 92 percent of low-income communities have less tree cover than wealthier ones. This is particularly pronounced in the Northeast.

Robert McDonald, that study’s lead author and the Nature Conservancy’s lead scientist for nature-based solutions, said researchers used satellite and digital imagery to determine that tree cover was on average 15.2 percent less for a low-income U.S. Census block compared to a high-income one. Poorer areas were hotter by an average of 1.5 degrees Celsius.

“Neighborhoods with less trees are hotter, and hotter neighborhoods are more deadly in heat waves,” McDonald said. “An inequality in tree cover is also inequality in climate risk.”

Although the findings of the Science Advances study are based on 2014 data, the most recent available to researchers at the time, they mirror the conclusions of the American Lung Association’s 2021 State of the Air report.

Using air quality data collected at federal, state, local and tribal government monitoring sites, it evaluated which areas had the highest levels of two harmful pollutants: fine-particle matter and ozone. Of the nearly 20.7 million people living in the 13 counties with failing grades for ozone, short-term particle pollution and year-round particle pollution, 14 million are people of color. Hispanics accounted for more than two-thirds of the total.

“People of color were 61 percent more likely than White people to live in a county with a failing grade for at least one pollutant,” the ALA report states, “and over three times as likely to live in a county with a failing grade for all three pollutants.”

Moreover, a third analysis released Wednesday by the Environmental Integrity Project shows that Americans of color face elevated exposure to benzene, a toxic air pollutant linked to cancer, because of their proximity to oil and gas refineries. While they represent 40 percent of the U.S. population, people of color made up almost 60 percent of the nearly 530,000 people who live within three miles of the 13 refineries that reported harmful levels of benzene last year.

“These are the kinds of communities hit especially hard by COVID-19, where residents who lack affordable health care already suffer from the kind of ailments that make them especially vulnerable to toxic air pollutants like benzene,” the study says.

Activists and scientists alike are pressing the Biden administration to take swift action to address these inequities. University of Minnesota engineering professor Jason Hill, a co-author of the Science Advances paper, said that national, state and local officials could redesign environmental policy in the same way they factored racial inequities into coronavirus vaccine distribution.

“Once you’re aware of these problems, it compels you to find new solutions,” Hill said.

Yet it remains unclear how sweeping an overhaul the Biden administration will attempt. The president’s infrastructure plan, which targets disadvantaged communities and those of color, needs congressional approval.

And while the EPA is moving to tighten mileage standards for cars and SUVs, it has not indicated what it will do on heavy-duty vehicles, which account for just 4 percent of traffic but nearly 60 percent of the transportation sector’s fine-particle emissions. A coalition of environmental and business groups sent the White House a letter last month demanding that it eliminate pollution from all new freight trucks and buses no later than 2040.

In Nevada, Moore has been pushing for passage of a law to close a loophole allowing cars with a classic-vehicle license plate to skip the state’s smog test. It would raise fees to help low-income drivers repair their cars or buy more efficient ones.

“They say they want to address this,” Moore said of legislators. “But in Nevada, any time there’s an increase of fees for businesses or individuals, it’s a problem.”

Correction: An earlier version of this story misnamed one of the publications that released a study Wednesday. It is Science Advances, not Scientific Advances.