Millions of Children Worldwide Develop Asthma Each Year Due to Traffic-Related Air Pollution

The researchers linked global datasets of NO2 concentrations, pediatric population distributions, and asthma incidence rates with epidemiological evidence relating traffic-derived NO2 pollution with asthma development in kids. They were then able to estimate the number of new pediatric asthma cases attributable to NO2 pollution in 194 countries and 125 major cities worldwide.

Key findings from the study published in The Lancet Planetary Health:

• An estimated 4 million children developed asthma each year from 2010 to 2015 due to exposure to NO2 pollution, which primarily comes motor vehicle exhaust.
• An estimated 13 percent of annual pediatric asthma incidence worldwide was linked to NO2 pollution.
• Among the 125 cities, NO2 accounted for 6 percent (Orlu, Nigeria) to 48 percent (Shanghai, China) of pediatric asthma incidence. NO2’s contribution exceeded 20 percent in 92 cities located in both developed and emerging economies.
• The top 10 highest NO2 contributions were estimated for eight cities in China (37 to 48 percent of pediatric asthma incidence) and for Moscow, Russia and Seoul, South Korea at 40 percent.
• The problem affects cities in the United States as well: Los Angeles, New York, Chicago, Las Vegas and Milwaukee were the top five cities in the U.S. with the highest percentage of pediatric asthma cases linked to polluted air.
• Nationally, the largest burdens related to air pollution were found in China at 760,000 cases of asthma per year, followed by India at 350,000 and the United States at 240,000.

Asthma is a chronic disease that makes it hard to breathe and results when the lung’s airways are inflamed. An estimated 235 million people worldwide currently have asthma, which can cause wheezing as well as life-threatening attacks.

The World Health Organization calls air pollution “a major environmental risk to health” and has established Air Quality Guidelines for NO2 and other air pollutants. The researchers estimate that most children lived in areas below the current WHO guideline of 21 parts per billion for annual average NO2. They also found that about 92 percent of the new pediatric asthma cases that were attributable to NO2 occurred in areas that already meet the WHO guideline.

“That finding suggests that the WHO guideline for NO2 may need to be re-evaluated to make sure it is sufficiently protective of children’s health,” said Pattanun Achakulwisut, PhD, lead author of the paper and a postdoctoral scientist at Milken Institute SPH.

The researchers found that in general, cities with high NO2 concentrations also had high levels of greenhouse gas emissions. Many of the solutions aimed at cleaning up the air would not only prevent new cases of asthma and other serious health problems but they would also attenuate global warming, Anenberg said.

Additional research must be done to more conclusively identify the causative agent within complex traffic emissions, said the researchers. This effort, along with more air pollution monitoring and epidemiological studies conducted in data-limited countries will help to refine the estimates of new asthma cases tied to traffic emissions, Anenberg and Achakulwisut added.

The paper, “Global, national, and urban burdens of paediatric asthma incidence attributable to ambient NO2 pollution: estimates from global datasets,” was published on April 10 in The Lancet Planetary Health.

Contacts and sources:
George Washington University

Citation: Global, national, and urban burdens of paediatric asthma incidence attributable to ambient NO2 pollution: estimates from global datasets.
Pattanun Achakulwisut, Prof Michael Brauer, Perry Hystad, Susan C Anenberg. The Lancet Planetary Health, 2019 DOI: 10.1016/S2542-5196(19)30046-4