Filtered diesel exhaust gases from its tiny particles can aggravate an allergic-induced lung failure

According to a new study published online by the American Thoracic Society, air pollution by diesel engines could worsen allergy-related lung disorders, especially when tiny particles are filtered out in the air. exhaust gas. American Journal of Respiratory and Critical Care Medicine.

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

In "Particle depletion does not correct the acute effects of air pollution and traffic-related allergens," Denise J. Wooding, MSc, and his coauthors present a randomized, controlled study of 14 non-smoking adults sensitive to at least one of three common allergens.

"We had previously demonstrated that diesel exhaust gases increased allergic reactions and decreased airflow in genetically predisposed individuals, but we wondered whether the elimination of particulate gases from Exhaust would mitigate these effects, "said Chris Carlsten, lead author of the study, Canada Research Chair in Respiratory Diseases of Occupational and Environmental Origin at the University of British Columbia. British.

In this crossover study, the 14 participants at different times were exposed in an air lab with only allergen, exhaust gas + allergen + diesel and exhaust gases. allergen more filtered. They also breathed air without exhaust gas or allergen, which served as a control.

After each exposure, participants were subjected to a commonly used test called methacholine challenge to determine how a patient was responding to an inhaled allergen. Neither they nor those who conducted the study knew what exposure they had undergone before being tested.

The researchers also measured the number of white blood cells, which gathers the body's immune response, but can "exaggerate" the allergens, thus causing respiratory problems.

The study revealed:

• Particulate depleted diesel exhaust gases produced by HEPA filtration and electrostatic precipitation generated higher NO2 levels than unfiltered diesel exhaust gases.
• Exposure to filtered diesel exhaust and allergens reduced the amount of air that participants could forcibly exhale in one second (FEV 1) more than allergens alone and more than the gases in the air. 39, unfiltered diesel exhaust and allergens.
• Increasing levels of white blood cells have been badociated with decreased FEV1 scores, suggesting that white blood cells "play a significant role in reducing lung function in the context of these exposures".
• The effects of filtered diesel exhaust gases on pulmonary function and white blood cells were more pronounced in participants genetically predisposed to oxidative stress, which occurs when there is an imbalance of free radicals and antioxidants in the body. body.

"The message to remember," said Dr. Carlsten, "is that technologies that remove particulate exhaust gases from diesel engines can not simply be considered beneficial to health, especially in vulnerable populations . "

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