Interstate 405 is one of the nation’s busiest highways, with more than 300,000 vehicles speeding, crawling, or outright stopped each day on the 10 lanes cutting through this Los Angeles suburb. Yards away sits an elementary school, where students and teachers breathe air tainted by all those tailpipes.

Parents at El Marino Language School understood the health risks and were determined to do something. Five years ago, they organized. They cleaned the soot that settled on their children’s desks. They brought in pollution-trapping plants. They pressed for high-grade air filters, taking their own air measurements, trooping into school board meetings to make their case and, finally, last summer getting what they’d asked for. “It took an army,” said parent Rania Sabty-Daily.

In traffic-clogged Southern California, plenty of people grasp the dangers of kids attending class close to busy roads and their largely invisible clouds of air pollution. But that’s not nearly so well understood in the rest of the country — even though the problem stretches from coast to coast.

Nearly 8,000 U.S. public schools lie within 500 feet of highways, truck routes, and other roads with significant traffic, according to a joint investigation by the Center for Public Integrity and Reveal from The Center for Investigative Reporting. That’s about one in every 11 public schools, serving roughly 4.4 million students and spread across every state in the nation. Thousands more private schools and Head Start centers are in the same fix.

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Pollution is higher on and near busy roads, a toxic mix that can stunt lung growth, trigger asthma attacks, contribute to heart disease, and raise the risk of cancer. Newer research suggests that what’s spewed out of tailpipes may also harm children’s ability to learn and could play a role in brain maladies associated with old age. Almost everyone gets a dose on a regular basis — tiny particles that batter the body’s defenses, carcinogens like benzene, chemicals called polycyclic aromatic hydrocarbons — but the people living, working, or trying to learn very close to roads with heavy traffic get more. And more is worse for health, especially among children.

“The expectation of every parent is that they’re sending their child to a safe environment,” said George Thurston, a population-health professor at the New York University School of Medicine. “And with this kind of pollution, they’re not.”

Certain types of air pollution announce themselves. London’s killer 1952 fog that blacked out the sun. California’s historic brown smog. Beijing’s gray air, so poisonous that it keeps children indoors and shortens lives. But we usually can’t see the pollution coming from our roads, so it’s easy to miss.

A nationwide changeover to vehicles that don’t pollute would be the ultimate fix, but that won’t come soon. Even a thus-far successful federal mandate to reduce the worst of that pollution, from big rigs and other diesel trucks, is still roughly a dozen years away from taking full effect — when today’s kindergartners graduate from high school. That’s because diesel engines are long-lived. Several million trucks on the road predate the standards, and no federal rules require them to be retrofitted.

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Recognizing the risks to children, California banned new school construction on land within 500 feet of freeways in 2003, with exceptions. The U.S. Environmental Protection Agency has warned school districts about traffic-pollution impacts since at least 2011 and recommends that school districts think carefully before picking sites near major roads or truck routes.

But districts across the country keep doing it. Nearly one in five schools that opened in the 2014–2015 school year, the most recent the federal government has fully tracked, was built by a busy road. That’s worse than the overall rate of schools near such roads — those with daily traffic of at least 30,000 vehicles or with a minimum of 10,000 vehicles but at least 500 trucks, the threshold the Center and Reveal used to define a busy thoroughfare.

“A lot of schools are built on cheap land,” said Tolle Graham, labor and environment coordinator for the Massachusetts Coalition for Occupational Safety and Health. “That’s part of the problem of why they get located where they do.”

Another reason: School districts and parent groups largely don’t know there’s a problem, according to interviews with school groups, teachers’ unions, and public-health experts. As a result, there’s no widespread effort by districts to clean the air inside schools already impacted by substantial traffic, even though studies at California schools show that high-grade air filters make a marked difference and the EPA recommends them.

Southern California’s air agency, the South Coast Air Quality Management District, earmarked settlements from polluting companies and other funds to cover the cost of such filtration at about 80 schools near freeways or other pollution sources. Nothing’s preventing other states from following the same model.

“The technology is well established, the installation is straightforward, and the maintenance is simple,” said district spokesperson Sam Atwood, who doesn’t recall officials from other states getting in touch to learn from his agency’s experience.

Darryl Alexander, the American Federation of Teachers’ health, safety, and wellness director, said federal incentives would help. The EPA released a guide in 2015 for reducing road pollution at schools, but school districts are under no obligation to follow it, assuming they even know it exists. The U.S. Department of Education, noting that school buildings are funded with state and local money, declined to say whether it makes recommendations about school siting or sets any requirements.

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The schools beside the highways, byways

Big cities, where empty land is a rarity and traffic much harder to avoid, are the places you’re most likely to find a school near a busy road. New York and Los Angeles, unsurprisingly, top the list.

But thousands of these schools are located in small and mid-sized cities, suburbs, and rural towns all across the country. Multiple schools are squeezed next to well-used roads in Newark — where residents are battling for clean-air improvements around their truck-heavy port — as well as in Memphis and Milwaukee, Albuquerque and Cleveland, Wichita and Anchorage.

The impact varies, because each situation is unique. The number, type, and age of the vehicles passing by, whether they’re moving at a constant speed or braking and accelerating, whether the wind frequently or rarely blows from the road to the school — each of these factors makes a difference. A congested local road could be worse than a highway.

The problem affects all sorts of kids, but is more pronounced in predominantly minority or low-income schools, driven largely by where public school students live.

Though minority and white students are equally likely to attend public schools in suburbs, where about 2,600 schools lie near busy roads, there’s an urban-rural divide. Minority students are much more likely than white students to attend public school in big cities, which account for nearly 3,000 schools near such roads. And they’re a lot less likely than white students to attend class in rural areas, where traffic is generally lighter. Big cities serve a higher percentage of low-income students, too.

That’s the major reason for a striking difference, according to the Center/Reveal analysis: 15 percent of schools where more than three-quarters of the students are racial or ethnic minorities are located near a busy road, compared with just 4 percent of schools where the demographics are reversed. And though the gap isn’t as wide, schools with more than three-quarters of students eligible for free or reduced-price lunches are also more likely to sit near such roads.

That’s troubling not only because the pollutants are bad for health generally, but also because they’re particularly bad for asthmatics — and low-income and minority children have higher rates of asthma. Some studies suggest that traffic pollution is, in fact, one of the causes of asthma.

Charter schools are part of the traffic-disparity story. They’re more likely to serve minority and low-income students and to be located in cities, and they’re far more likely than traditional public schools to be near busy roads. They can be found in shopping centers, old warehouse buildings, and other spots that were built with commerce — and traffic — in mind.

But what looms much larger is how decades-old discriminatory decisions by officials continue to play a role in who gets exposed to more traffic pollution today. Redlining, the racist lending that was official federal policy until 1968, shaped American neighborhoods in ways that still persist. The post-World War II highway boom exploded through minority neighborhoods across the country.

Gilbert Estrada, an assistant professor at Long Beach City College in California who studied the history of freeways in the Los Angeles area, said Mexican-American communities took the brunt of that construction there. Wealthier places used their greater political clout to scuttle freeways near them. Costs pressed state officials to go where the land values were cheapest. That’s had health and learning implications for generations of children.

“The studies have shown the students can’t concentrate, that they have lower test scores, … that they have higher rates of asthma,” said Estrada, who grew up in Commerce, California, a community split by two major freeways. “These are pollutants that can transform your DNA. … You just can’t take that back.”

Students line up outside El Marino Language School as vehicles zoom by on Interstate 405 in Culver City, California.

Students line up outside El Marino Language School as vehicles zoom by on Interstate 405 in Culver City, California. Courtesy of Stephon Litwinczuk

The parents and the freeway

The teachers were worried first.

At El Marino Language School in Culver City, on the western edge of Los Angeles, educators could hear the omnipresent shoooosh of traffic on the 405. They could see the dark dust that collected on surfaces — “no matter how many times we dusted or swept or mopped,” said Cristina Paul, who taught second grade there until last summer. They particularly raised concerns when the 405 was widened about a decade ago, bringing it even closer to the school. But not much happened until the parents started to worry, too.

Among them were Rania Sabty-Daily, who’d fortuitously earned a Ph.D. in environmental health sciences, and Stephon Litwinczuk, a filmmaker who knew the freeway would not be good for his twin sons, both of whom have a lung condition called reactive airway disease. The parents faced headwinds when they started down this path five years ago: assumptions that ocean breezes kept the air clean. Concerns from nearby residents that discussing the problem would lower their home values. And, of course, cost — because the school has no central air conditioning, air filtering would be harder and more expensive to do.

Parent Rania Sabty-Daily, standing by El Marino with cleaning supplies to combat the 405's pollution. "It took an army," she said.

Parent Rania Sabty-Daily, standing by El Marino with cleaning supplies to combat the 405’s pollution. “It took an army,” she said. Courtesy of Stephon Litwinczuk

The parents and teachers who joined forces decided that success would lie in convincing people there was indeed a problem, but that there were constructive steps they could take together. Sabty-Daily borrowed university equipment that measures ultrafine particles — the smallest of the too-small-to-see specks that spike near roads, and which health researchers are particularly worried about — and showed that the sea breezes actually were blowing road pollution toward the school. Parents wiped down classrooms with microfiber cloths to clear out both the visible and invisible remnants of the road. Litwinczuk made videos to keep everyone in the loop. Christina Dronen, another volunteer, started a no-idling campaign and filled her daughter’s classroom with air-cleaning plants as she waited for the filters she couldn’t believe weren’t already in place.

Parents went to school board meetings — lots of them — and worked to elect more receptive board members. They started a PTA committee and teamed up with their supportive principal. They campaigned for a bond measure to get money for a schoolwide filtration and air-conditioning system.

Even after voters approved the bond measure in June 2014, it remained a slog. Dronen’s daughter started and ended second grade the next school year with no air filtration system. That spring, a friend abruptly pulled her children out of El Marino and shared the public-health studies that convinced her — the links to childhood cancer, slower cognitive development, and lung problems. Dronen read them and made a wrenching decision: That fall, she would send her daughter to another school.

If she didn’t and her daughter’s health suffered, “I felt like I would never be able to live with it. So I pulled her out. I spoke in front of the school board … ‘Year after year, she’s there, and you keep saying “someday.” ’ ”

Another year went by after that. But last summer, the filtration system started going in.

Mike Reynolds, assistant superintendent of business services at the Culver City Unified School District and a supportive voice for the El Marino efforts, understands why some parents got frustrated. Launching a school construction project “takes forever,” he said. Workers had to retrofit the heating system to install the filters, and this summer they will add air conditioning so teachers can keep doors and windows closed. Total cost: $2.5 million.

The campus opened in 1952 — predating the 405 — and has classroom doors that open directly outside. Exactly what you don’t want when you have several hundred thousand pollution sources passing by every day.

El Marino’s project doesn’t fix the outdoor air the kids breathe while playing at recess or eating lunch. But the South Coast air district found that a test run of filters in an El Marino classroom, conducted before the full system went in, removed more than 90 percent of unhealthy particles indoors — similar to the effect the agency found at other schools that installed high-grade air filters. To put that into context: Just 20 to 50 percent of the particles were caught by schools’ earlier efforts, according to the agency.

That’s good for the kids, some of whom are there 12 hours a day, including before- and after-school care. It’s good for the employees, too, because they’re also breathing that air.

Roberta Sergant, a longtime El Marino teacher active in the clean-air effort, was diagnosed with breast cancer six months after she retired. She wonders whether carcinogens from the freeway’s 300,000-plus vehicles a day — including more than 8,000 trucks — played a role. Years before her diagnosis, she’d had genetic testing that showed that despite her mother’s breast cancer, “I had no gene that was an alarm for cancer at all.”

She understands why people worked so hard to do something about the air. Families love the school, which offers language immersion programs in Japanese and Spanish. Her own grandchildren are at El Marino.

So is Dronen’s kindergarten-age son. Getting her daughter reenrolled has proved challenging, but she’s hoping that will work out, too. The school has filters now — that made all the difference for her.

Visible and invisible risks

New cars and trucks are much cleaner than those built decades ago, thanks to federal rules for vehicles and fuel — once, tailpipes used to pump out brain-damaging lead. Still, there’s a lot more traffic on the roads now, and it remains a major source of U.S. air pollution.

Some of our exhaust feeds climate problems: A quarter of U.S. greenhouse-gas emissions in 2014 came from transportation, the lion’s share of that from vehicles on the road, according to the EPA. Then there are the unhealthy chemicals and tiny particles that affect more than just our lungs.

“Once it gets into your body, gets into the blood, it’s off to the races,” said Ed Avol, a professor in the University of Southern California’s Department of Preventive Medicine, part of a team that has conducted sustained research on the health effects of living and attending school near traffic. “All body systems are at risk.”

There’s a federal standard for small particles, ones measured at less than 10 microns (roughly one-seventh the width of a single hair), as well as for tiny particles, ones measured at less than 2.5 microns (one-thirtieth the width of that hair). But there’s nothing for the smallest of all — ultrafine particles, less than a tenth of a micron.

Research in recent years suggests that ultrafines could be worse for health in many ways than their larger cousins because they can slip into the bloodstream, bringing toxic materials with them. These are the particles that spike near roads, along with other types of traffic pollution such as volatile organic compounds.

But there’s not enough exposure data to determine the full health impact because there’s so little ultrafine monitoring, said Philip K. Hopke, distinguished professor emeritus at Clarkson University in New York. Hopke, a former chairman of the EPA’s Clean Air Scientific Advisory Committee, said he’s pressed the agency to set up a nationwide network. The EPA said in a statement that it has encouraged states to measure, and several do, but it does not require monitoring because there’s no ultrafine air-quality standard.

“We can’t have a standard if we don’t have data, but we don’t have data because we don’t have a standard so there’s no need to spend money on making measurements,” Hopke said. “We’ve got to find a way of breaking the catch-22.”

The good news about bad particles is fewer of them are now coming from diesel trucks. Diesel engines made in and after the 2007 model year are much cleaner than earlier versions, the result of more stringent EPA rules.

But lots of old, dirty trucks remain on the road. More than 60 percent of diesel trucks registered in the U.S. predate the cleaner-engine standards, according to the Diesel Technology Forum. The Texas A&M Transportation Institute, estimating the typical mix of vehicles on the roads today, calculated that a heavy-duty diesel truck puts out 63 times the fine particles of a gasoline car on a highway. That rises to 129 times the fine particles when on a road with stop signs or traffic lights, because accelerating trucks put out more pollution.

The EPA has funneled grants totaling hundreds of millions of dollars toward replacing old diesel school buses, trucks, and other equipment since 2008, but the Diesel Emissions Reduction Act, which authorized that money, lapsed last year. The program has some funding for now because prior-year levels were temporarily extended to give Congress more time to approve a budget, but its fate is uncertain.

New regulations to address traffic pollution don’t look likely, either. President Donald Trump signed an executive order requiring that the federal government get rid of two rules for every new one adopted, his EPA transition-team leader called for deep cuts at the agency, and Trump told auto executives in January that environmental regulations are “out of control.” An auto industry group already has asked the administration to loosen higher fuel economy requirements — which have a side benefit of reducing air pollution — that are due to phase in through 2025.

For schools near busy roads, that increases the importance of local efforts such as better air filtration. But the National PTA couldn’t find examples of parents working on the issue. Though some school districts are, the National Association of State Boards of Education thinks it’s not on most school officials’ radar yet, either.

“It’s really an invisible problem,” said Paul, the schoolteacher who previously worked at El Marino. “It would be different if it were a public health and safety problem that were presenting itself physically and visually. If all of our toilets were overflowing, then people would be so upset.”

Tamika Bowers and her 10-year-old son, Tíyonn, outside an Ironbound Community Corp. building beside Tíyonn's school.

Tamika Bowers and her 10-year-old son, Tíyonn, outside an Ironbound Community Corp. building beside Tíyonn’s school. Jamie Smith Hopkins / The Center for Public Integrity

The port’s neighbors

The problem is more obvious in some places. Take the Ironbound. It’s a Newark neighborhood known for its Portuguese restaurants, large immigrant communities, and ongoing battle with trucks. They’re inescapable here: container trucks, delivery trucks, trash trucks, and sewage trucks, passing by schools, rumbling down narrow roads, blocking streets.

The Newark community abuts the Port of New York and New Jersey, third-largest seaport in the country, and some of the trucks are going to or coming from there. Others are connected with businesses that want to be near the port or find the location convenient for other reasons, like the fast hop to Interstate 95. Most of the trucks are old, which means they pump out more of the unhealthy particles that are bad for the lungs, heart, and likely the brain. This older diesel exhaust can also cause cancer, unlike what research suggests about the exhaust from newer engines.

Diesel particle levels are higher in the Ironbound than in the vast majority of the country, particularly the section closest to the port, according to EPA estimates. The same is true of the respiratory health risks from bad air. On the EPA’s Environmental Justice Screening and Mapping Tool, that’s represented as a mass of orange and red layered over the community, like a bloody wound.

“Living down here,” said Tamika Bowers, “is a stressful situation.”

Hawkins Street School in Newark seen through the gap of a container truck.

Hawkins Street School in Newark seen through the gap of a container truck. Jamie Smith Hopkins / The Center for Public Integrity

She and her 10-year-old son, Tíyonn, both have asthma. She sleeps with her rescue inhaler under her pillow. Tíyonn needs medication to keep his lungs working properly and struggles with congestion. He feels safer inside, figuring the air is better, but he’s never far from the trucks.

They rumble past Hawkins Street School, the elementary/middle school he attends — an estimated 585 trucks a day on a two-lane road, along with roughly 11,000 other vehicles. They idle, like the truck outside school as Tíyonn left that day in December, pumping out gray smoke he could smell. Airplanes headed to the nearby Newark Liberty International Airport fly low over his school every couple of minutes, adding more pollution and noise.

“It’s so bad,” Tíyonn said, “I feel like we should have moved.”

Some in this working-class community with a mix of narrow, modest homes and public housing can’t afford to do that. Some don’t want to be driven out of a place they love, where many speak more than one language and the crime rate ranks among the lowest of Newark’s neighborhoods.

Kim Gaddy, a Newark school board member and environmental-justice organizer, thinks too many kids and adults in the city are exposed to unhealthy levels of traffic pollution, particularly in the Ironbound and in the South Ward neighborhoods that are also close to the port. Gaddy, a South Ward resident, has asthma and so do all three of her children. No one appears to track child asthma rates in Newark, but the best guess — the one repeated by officials — is that one in four children in the city has it. The asthma hospitalization rate for all ages, something New Jersey does track, was nearly three times higher in Newark than in the rest of the state in 2015.

“We have to look at this as a health injustice,” Gaddy said. “Our children, their life is on the line because we can’t escape the diesel.”

Driving around her neighborhood recently, pointing out the trucks and truck-intensive businesses, she paused outside the B.R.I.C.K. Peshine Academy school. Students were outside for recess, playing in the biting cold. Across the street and down a hill was Interstate 78, where roughly 160,000 vehicles, including more than 11,000 trucks, pass by every day.

The hill is good: The EPA has found that below-grade roads reduce the impact of traffic pollution nearby. (Hawkins Street School has no such luck, and its road is even closer, with a traffic light that guarantees pollution spikes from acceleration.) But the number of trucks on I-78 is unusually high.

All told, about 40 public schools in Newark — roughly 40 percent — are within 500 feet of a busy road.

John M. Abeigon, president of the Newark Teachers Union, has no doubt that proximity is unhealthy. He moved his family from the Ironbound to a Newark suburb in 1997 after his daughter developed asthma, and her symptoms quickly cleared up. But he says no one should expect the school district to find the money for high-grade air filters.

“Yeah, that’s not going to happen here,” he said. “They don’t have $75 for a water filter to keep lead out of the students’ drinking water.”

The Newark school district said its schools do have air filters and change them regularly, but they’re run-of-the-mill, regardless of whether a pollution source is nearby. That meets state requirements, schools spokesperson Paul Nedeau wrote in an email. But this is a city that has long struggled with pollution, he said, and the district is eager to work with partners to improve conditions in and around its schools.

Among the most active local groups on pollution issues is the nonprofit Ironbound Community Corp., which thinks schools and residents shouldn’t have to pay for the air-quality problems they didn’t create. For more than a decade, ICC staffers and volunteers have called on the Port of New York and New Jersey — the destination for 9,000 trucks a day — to do more.

About 62 percent of the trucks that go to and from the port predate the stricter 2007 engine standards. The Port Authority of New York and New Jersey said in 2010 that it would bar those trucks in January 2017, but last year it weakened the plan. Old trucks not already serving the port are prohibited, but a ban affecting the current stock won’t kick in until next year — and only on trucks from 1995 or earlier.

Molly Campbell, director of port commerce for the authority, blamed it on lack of funding. The authority doesn’t have the money to assist all the people with older trucks, she said, many of whom are one-man independent contractors.

That sounds like a cop-out to Ana Baptista, an assistant professor at the New School in New York and a Hawkins Street graduate who previously led environmental-justice efforts at the ICC. The ports of Los Angeles and Long Beach in California — the only two larger than New York’s and New Jersey’s — banned pre-2007 trucks five years ago, cutting their diesel particle pollution more than 80 percent. Those ports also set aside funds for air filtration in schools, something the New York and New Jersey port said it has not done.

Campbell, who came from the Los Angeles port, points out that California ultimately required all older diesel trucks, not just those bound for ports, to get anti-pollution retrofits or get off the road. It’s the only state to do so, and she thinks that makes more sense than demanding that one employer do better.

Still, nothing like that is in the works in New Jersey or New York. In December, when the port authority and the EPA held an air pollution “listening session” in Newark, dozens of people from the Ironbound, the South Ward, and other communities filed in to say they’re confident the authority — a quasi-governmental agency with a $3 billion operating budget — is not doing what it could and should.

Two elected officials said the port must move more expeditiously to help the people breathing in the exhaust of this regional economic engine. People repeatedly pointed to clean-air efforts at the California ports. Several called for air filtration and pollution-trapping trees. Baptista said the port authority is spending big on capital investments and must make clean air a priority as well.

“Just this week, another child died from asthma here in the city of Newark,” said Amy Goldsmith with the Coalition for Healthy Ports. Gaddy told the officials that her brother-in-law died of an asthma attack five minutes from the port. “It is time,” said the ICC’s Molly Greenberg, to cheers and applause, “that people stop having to pay with their lives.”

Hopkins reported this story with the support of the Dennis A. Hunt Fund for Health Journalism and the National Fellowship, programs of the University of Southern California Center for Health Journalism.

Center for Public Integrity news developer Chris Zubak-Skees contributed to this story.