Air pollution triggers up to 33 million emergency room visits for asthma annually, finds major new study

Up to 33 million emergency hospital visits for asthma worldwide are triggered by breathing in air polluted by ozone or fine particulate matter — pollutants that can enter the lung’s deep airways, according to a study published today, co-authored by SEI researchers.

“Millions of people worldwide have to go to emergency rooms for asthma attacks every year because they are breathing dirty air,” said Susan C. Anenberg, lead author of the study and Associate Professor of Environmental and Occupational Health at the George Washington University Milken Institute School of Public Health. “Our findings suggest that policies aimed at cleaning up the air can reduce the global burden of asthma and improve respiratory health around the world.”

Asthma is the most prevalent chronic respiratory disease worldwide, affecting about 358 million people.

Evidence mounts on health impacts of air pollution

Scientists have long known that breathing in air sullied by car emissions and other pollutants could trigger asthma attacks. However, the new study, published in the journal Environmental Health Perspectives, is the first to quantify air pollution’s impact on asthma cases around the globe.

“SEI’s recent research has shown how air pollution is linked to millions of pre-term births as well up to a million premature deaths each year from respiratory diseases. Yet many more people suffer poor health caused by non-fatal diseases linked to dirty air. The problem has been that these have been difficult to quantify,” said SEI researcher and co-author of the study Chris Malley.

The research team first looked at emergency room visits for asthma in 54 countries and Hong Kong, and then combined that information with epidemiological exposure-response relationships and global pollution levels derived from satellites orbiting the earth.

The new research suggests that:

• Nine to 23 million annual asthma emergency room visits globally (8 to 20% of total global asthma ER visits) may be triggered by ozone, a pollutant generated when car, power plant and other types of emissions interact with sunlight.
• Five to 10 million asthma emergency room visits every year (4 to 9%) of total global asthma ER visits) were linked to fine particulate matter.
• About half of the asthma emergency room visits attributed to dirty air were estimated to occur in South and East Asian countries, notably India and China.

Asia hardest hit – solutions proposed

Countries like India and China are more affected by the asthma burden because of large populations and fewer restrictions on emissions from industry and other sources of pollution, which can then trigger breathing difficulties, the authors said.

The findings underscore the urgency of finding solutions to air pollution and come ahead of the release next week of a major report co-authored by SEI, Air Pollution in Asia and the Pacific: Science-based Solutions. The report is the first comprehensive, solution-oriented, scientific assessment of the air pollution outlook and policy measures in Asia and the Pacific, and will be launched next week at the first WHO Global Conference on Air Pollution and Health in Geneva.

The report states that four billion people – 92% of the region’s population – are exposed to levels of air pollution that pose significant risks to their health.

It details a portfolio of 25 measures for technological and policy interventions to tackle air pollution and deliver benefits for human health, crop yields, climate and the environment. These include conventional measures, such as state-of-the-art end-of-pipe measures to reduce sulphur dioxide, nitrogen oxides and particulate emissions at power stations and in large-scale industry, and “next-stage” air quality measures that are not yet major components of clean air policies in many parts of Asia and the Pacific, such as better management of agricultural residues, including strict enforcement of bans on open burning.

Satellite data

To estimate the global levels of pollution for this study, the researchers turned to atmospheric models, ground monitors and satellites equipped with remote-sensing devices.

“The value of using satellites is that we were able to obtain a consistent measure of air pollution concentrations throughout the world,” said Daven Henze, co-author and Associate Professor for the University of Colorado Boulder. “This information allowed us to link the asthma burden to air pollution even in parts of the world where ambient air quality measurements have not been available.”

The international, multi-institutional research team included scientists from the George Washington University Milken Institute School of Public Health, the National Aeronautics and Space Administration (NASA), the Stockholm Environment Institute, the Japan Agency for Marine-Earth Science and Technology, the Norwegian Meteorological Institute, and others.

“Estimates of the global burden of ambient PM_2.5, ozone, and NO₂ on asthma incidence and emergency room visits,” appeared online 24 October in the journal Environmental Health Perspectives.