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Friday, April 12th 2019

Diesel exhaust filtered of its tiny particles may worsen allergyinduced lung impairment

by American Thoracic Society

Air pollution from diesel engines may worsen allergy-induced lung impairment more when tiny particles are filtered from the exhaust than when they are not, according to new research published online in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.

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Air pollution from diesel engines may worsen allergy-induced lung impairment more when tiny particles are filtered from the exhaust than when they are not, according to new research published online in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.

This surprising result may be due to the fact that some particle-depletion technologies, including the one used by the researchers, increase the amount of nitrogen dioxide (NO2) in the exhaust. NO2, which is subject to national air quality standards, has been shown to reduce lung function and may be a cause of asthma in children.

In "Particle Depletion Does Not Remediate Acute Effects of Traffic-Related Air Pollution and Allergen," Denise J. Wooding, MSc, and co-authors report on a randomized, controlled study of 14 non-smoking adults who were sensitive to at least one of three common allergens.

"We previously demonstrated that diesel exhaust augmented allergic responses as well as airflow declines in those genetically susceptible, but we wondered if removing particles from the exhaust would lessen these effects," said senior study author Chris Carlsten, MD, MPH, professor, head of respiratory medicine and Canada Research Chair in Occupational and Environmental Lung Disease at the University of British Columbia.

In this cross-over study, all 14 participants at various times were exposed in a laboratory to air with just the allergen, the allergen plus diesel exhaust and the allergen plus filtered diesel exhaust. They all also breathed air with no diesel exhaust or allergen, which served as the control.

After each exposure, the participants underwent a commonly used test called methacholine challenge to determine how a patient responds to an inhaled allergen. Neither they nor those conducting the study were aware of which exposure they had undergone before being tested.

The researchers also measured numbers of white blood cells, which marshal the body's immune response but can "overreact" to allergens, causing breathing problems.

The study found:

"The take-home message," said Dr. Carlsten, "is that technologies that remove particulate matter from diesel exhaust cannot be simply assumed to be beneficial to health, especially in susceptible populations."

Learn More from American Thoracic Society