Milken researchers link traffic pollution to 4 million annual cases of childhood asthma

Media Credit: Courtesy of Susan Anenberg

Susan Anenberg, an associate professor of environmental and occupational health, said the study shows that air pollution is linked to asthma among children.

Researchers in the Milken Institute School of Public Health published a study last week estimating that traffic-related air pollution causes 4 million cases of childhood asthma worldwide annually.

A team of four researchers examined 2015 data from the Institute for Health Metrics and Evaluation – an organization that publishes global health statistics – on asthma rates in 194 countries, 125 cities and multiple age groups. Researchers said their findings could encourage policy experts to push for more substantive regulations to reduce human-created pollution that causes asthma attacks.

Pattanun Achakulwisut, a postdoctoral scientist in the public health school and an author of the study, said policymakers could cite the study’s results when pushing for “cleaner” forms of transportation, like electric public transportation and bicycles.

“Traffic pollution appears to be a substantial risk factor for childhood asthma incidence in both developed and developing countries, and especially in cities, and should therefore be a target for exposure-mitigation policies,” Achakulwisut said in an email.

She said the study estimates that more than one in 10 asthma cases developed between 2010 and 2015 may be linked to traffic-related air pollution. Achakulwisut said nitrogen dioxide, a pollutant found in automobile exhaust, is a common cause of childhood asthma.

She said that within the 125 cities investigated, the percentage of new pediatric asthma cases that could be attributed to traffic pollution ranged from 6 percent in Orlu, Nigeria to 48 percent in Shanghai. Achakulwisut said the countries with the highest rates of childhood asthma linked to traffic pollution are China, Russia and South Korea.

She said scientists can estimate high nitrogen dioxide concentrations near major roadways using satellites and data mining techniques. The team combined the dataset with existing research about asthma and traffic pollution to examine how nitrogen dioxide pollution affects asthma rates around the world, Achakulwisut said.

“Our research team was able to quantify, for the first time, the worldwide impacts of NO2 pollution in a way that more accurately reflects where children live and how close they are to traffic pollution hotspots,” she said.

Susan Anenberg, an associate professor of environmental and occupational health and another author of the study, said the results revealed that more than one in five new cases of pediatric asthma are linked to traffic-related air pollution.

Anenberg said determining that air pollution is linked to pediatric asthma allows researchers to better assess the impacts of man-made air pollution.

“Before this study, leading estimates of the risk factors affecting global public health have not included the impacts of air pollution on asthma,” she said. “Our research shows that the public health consequences of air pollution are more far-reaching than previously thought.”

Anenberg said the team did not receive external funding for the research but conducted the analysis with support from the public health school.

Asthma experts said increasing public knowledge of the link between traffic-related air pollutants and asthma will encourage legislators to put forth measures aiming to decrease human-produced air pollutants.

William Lambert, an associate professor of epidemiology and environmental systems and human health at Portland State University, said the data will encourage policymakers to enact legislation preventing and treating childhood asthma.

“Childhood asthma, just like asthma in adults, can’t be cured,” he said. “The symptoms of asthma are well-known and severely limit the quality of life. This is why we worry about traffic-related air pollutants and exposures to children who may live and attend school or exercise in areas near highways.”

David Turcotte, a professor of economics who researches environmental justice and asthma at the University of Massachusetts Lowell, said policymakers should ensure that residential developments are not built near major highways and roads so children breathe clean air at home.

“I think it’s extremely important because the rate of asthma for children, as well as adults, have increased noticeably in the past few years, and that it’s a serious issue,” he said.

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