Communities with larger Asian populations had higher levels of seven components. Asians registered far greater exposures than whites to nickel, nitrate and vanadium.
And areas where more African Americans lived showed significant elevations in four compounds, including sulfate and zinc.
People with less than a high-school education, unemployed or living in poverty had more exposure to several components, including silicon and zinc. Also, children and teenagers were more likely than adults to breathe most of the substances.
The demographic differences raise important policy questions, said Rachel Morello-Frosch, an associate professor at the University of California, Berkeley, who studies the health risks of air pollution but was not involved in the Yale study.
Census tracts with a larger proportion of Hispanics had significantly higher levels of 11 substances, including more than 1.5 times the whites' exposures to nickel, nitrate, silicon, vanadium and aluminum.She said targeted monitoring may be needed in problem areas. “Then regulatory agencies may want to assess how they can encourage emissions reductions from sources that are having localized impacts,” Morello-Frosch said.
It’s a common scenario in cities nationwide: Due to high housing costs and historical discrimination, low-income and minority neighborhoods are clustered around industrial sites, truck routes, ports and other air pollution hotspots.
In the South Bronx, a largely Hispanic and African-American district of New York City, nearly four in 10 live in poverty. Heavy traffic and a jumble of small industries taint the air with a load of fine particles that frequently exceeds the federal health limit.
Asthma rates are as much as four times higher in the Bronx than the national rates, said Dr. Norman Edelman, chief medical officer for the American Lung Association. “They live near highways, they live near where trucks spew diesel,” Edelman said. “That’s the least desirable housing… much different than a nice, leafy suburb.”
And just south of Pittsburgh, a slice of the Monongahela River Valley known as Liberty-Clairton tops the EPA charts with the nation’s worst fine particle pollution outside of California.
Clairton, a mill town, is “home to the [U.S. Steel] Clairton Coke Works, which is the largest coke-making facility in the nation,” said Rachel Filippini, executive director of the environmental organization Group Against Smog and Pollution. “The process of making coke is a pretty dirty one with lots of particulates and air toxics.”
Tom Hoffman, Western Pennsylvania director of the environmental group Clean Water Action, said childhood asthma is rampant in Clairton, but a lot of families in the hardscrabble town don’t have medical coverage. In some homes, the whole family shares a single inhaler, he said.
Particulates are complicated
The health effects of fine particle pollution are well-documented: Studies worldwide have shown that on days when fine particle concentrations increase in a community, more people die from heart attacks and respiratory problems.
But far less is known about whether specific types of particles translate to greater rates of illness or death.
“Some of these particles are not only composed of different things, but there are different gases and other things that adhere to them on the outside. So they’re complicated in a whole range of ways,” said Janice Nolen, author of the American Lung Association’s annual State of the Air Report.
Studies on the components are limited and have given varying results. But some associations are clear.
Sulfate, for instance, can trigger asthma attacks, while vanadium irritates lungs, and nitrate causes inflammation that may lead to heart attacks or strokes. Within cities, some studies have found cardiovascular deaths rise with certain particles, including nitrate, zinc, nickel, carbon, selenium and silicon.