Since the US Clean Air Act’s passage in the 1970s, there have been a steady stream of reports correlating exposure to air pollutants with a variety of health impacts. But in the early days, much of that information was too rudimentary to be of much use. Monitoring technology has improved in the decades since, and state air-quality boards have amassed volumes of actionable data about air pollution.



The increase in available data coupled with advances in chemistry and 3D modeling over the past few years has enabled scientists to identify new particle systems within air pollution. Researchers are now able to determine all the various chemicals and particles that air pollution includes, and to study precisely how these various elements interact with, and in some cases fundamentally change, the human body.

Those advances have led to a rapid increase in published studies about air pollution over the past year, as researchers have focused their work on the interaction between pollution particles and human health. Multiple long-term studies of human health are beginning to produce results, as are ongoing studies of air pollution. Three studies published just last week illustrate the state of rapidly advancing science around air pollution today.

In one study, Louisiana State University researcher Stephania Cormier reported that a particular type of free radicals (called environmentally persistent free radicals, or EPFRs), formed within the particulate matter emitted by cooking stoves, cars, factories, waste incinerators, wood fires, and cigarettes, can cause damage human cells.

The findings could have broad implications for businesses, considering that the Supreme Court is currently wrestling with how to interpret the Clean Air Act.

Cormier and her team divided a population of mice into two groups, exposing one to EPFRs and the other to no pollution. They then infected both groups with a flu virus.



The pollution-exposed mice were rendered virtually defenseless to the virus: 20% more of them died from the flu. Instead of fighting off the disease, their bodies reacted by triggering an anti-inflammatory signal, Interleukin-10, and switching on both an immune-regulating protein called aryl hydrocarbon receptor and immune cells called regulatory T cells, both of which turn off the body’s defenses against infection.

The researchers also found that the EPFRs caused oxidative stress, an imbalance between the production of free radicals and the ability of the body to counteract or detoxify their harmful effects.

What that means for similarly exposed communities is that asthma and the flu will be more severe for vulnerable members, like infants and the elderly.

More and worse allergies

Another study, published on 22 March by researchers at the Max Planck Institute for Chemistry in Germany, found that common traffic-related air pollutants may make allergies more severe.

The study’s authors conducted lab tests and computer simulations to study the effect of ozone and nitrogen dioxide on a primary birch pollen, Bet v1, and found that both pollutants affected how proteins in the pollen bound together, potentially creating a more potent allergen.

“Our research is showing that chemical modifications of allergenic proteins may play an important role in the increasing prevalence of allergies worldwide,” Christopher Kampf, one of the study’s authors, said in a statement.

Impact on the brain

Yet another study released last week, this one a collaborative effort between researchers at the Institute for the Developing Mind at Children’s Hospital Los Angeles and at Columbia University’s Center for Children’s Environmental Health, found a connection between common pollutants found in a wide range of emissions and cognitive and behavioral impairment.

The study looked at the effects of airborne polycyclic aromatic hydrocarbon (PAH), a molecule prevalent in emissions from motor vehicles, oil and coal burning, wildfires and agricultural burning, hazardous waste sites, and tobacco smoke as well as charred foods.

The research team selected 40 minority youth, born to Latina or African American women, that Columbia researchers have been following from birth, and used magnetic resonance imaging (MRI) to measure their brains.

The Columbia researchers had previously reported that PAH exposure during gestation in this group was associated with multiple neurodevelopmental disturbances, including development delay by age 3, reduced verbal IQ at age 5, and symptoms of anxiety and depression at age 7.

In the group of 40 studied in the MRI test, the researchers found a loss of the brain’s white matter surface, which correlates to slower processing of information and severe behavioral problems, including ADHD and aggression.

Postnatal PAH exposure – measured at age 5 – was found to contribute to additional disturbances in development of white matter in a separate area of the brain, one associated with concentration, reasoning, judgment, and problem-solving ability.

“This sample of 40 was quite ‘pure,’ in that their exposure to other known neurotoxicants was minimal, so we have more confidence in being able to attribute the brain abnormalities to the effects of prenatal and early childhood exposure to PAH,” Peterson said.

While the study group was small, Peterson said these results emphasize what we already know about the harmful effects of tobacco and add to the growing base of knowledge about the impacts of other sources of air pollution. Given the mounting evidence, he said, clinicians should educate prospective parents about these risks, especially in early pregnancy.

Peterson said that in less urban areas, exposure to pollutants from wildfires, agricultural burning and hazardous waste sites might be more relevant, and that women and children should remain indoors and use air conditioners as much as possible to avoid the airborne products of these fires.

“As the link between air-borne pollutants and adverse brain changes is linear and seems not to have any threshold that defines safe and unsafe exposure, any reduction in exposure during the most active periods of brain development – in fetal life and in early childhood – will be helpful.”

Translating research into action

According to the most recent American Lung Association State of the Air report, more than half of Americans live in areas with dangerously high levels of air pollution.

Children are the most severely impacted by air pollution, both in utero and in early childhood.

Air pollution also remains an issue of class and race. The dominant sources of pollution – traffic, industrial emissions, energy-related emissions (from oil refineries and coal plants), and hazardous waste – all disproportionately affect low-income and minority communities.

The quickest way to improve the air quality of all communities is increased state and federal regulation of the sources of air pollution. To that end, the US Supreme Court is due to address two major Environmental Protection Agency rules this summer, one that aims to regulate cross-state air pollution and one that would require better pollution controls on coal power plants.

Both have been criticized for being expensive and onerous to implement, but Supreme Court justices in favor of the rules have pointed to the EPA’s obligation to protect public health, not private profits.

Judge Judith W Rogers wrote as much in the majority opinion on the EPA’s mercury rule, which would require coal power plants to install scrubbers that would limit mercury emissions, costing them $9.6bn a year. Rogers said the EPA’s focus on “factors relating to public health hazards, and not industry’s objections that emission controls are costly” should motivate Congress to make appropriate and necessary regulatory rules.

Moreover, because the scrubbers required would also reduce other air pollutants, the EPA has estimated that the rule would save $26bn to $89bn per year in healthcare costs. The latest batch of air pollution research helpssupport that claim.

“I hope that these studies and others like them will convince public-policy makers to address air pollution in our cities,” Peterson said.

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