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Filtered diesel exhaust could be even worse for some people than the unfiltered one

Diesel engines are getting a lot of heat in recent years. The problem is that their exhaust gasses are really toxic and can potentially cause cancer. The solution would be to filter them, but does that really work? Scientists from the University of British Columbia say that filtered air pollution from diesel engines could make allergy-induced lung impairment even worse.

Filtered diesel exhaust is enriched with NO2, which contributes to allergy-induced lung impairment and can even cause asthma in children. Image credit: Ruben de Rijcke via Wikimedia (CC BY-SA 3.0)

This is some weird information to take in, but, apparently, it is correct – filtered diesel exhaust is even worse for allergy-induced lung impairment than the unfiltered one. But how can this be? Scientists say that some particle-depletion technologies increase the amount of nitrogen dioxide in the exhaust. And NO2 is no joke – it is proven to be damaging to people and can even cause asthma in children. So-called NOx emissions are actually the reason why diesel engines are getting banned from certain cities in Europe. Filtering, apparently, is not a great solution either.

Scientists conducted a randomized, controlled study of 14 non-smoking adults. Researchers selected those individuals who were sensitive to at least one of three common allergens. In a laboratory each participant was exposed to the allergen, allergen with diesel exhaust or the allergen plus filtered diesel exhaust. People in control group were just breathing air. Participants underwent a commonly used test after each exposure. It determined how they responded to the exposure and helped researchers to determine what kind of effect diesel exhaust actually has. As mentioned before, diesel exhaust produced by HEPA filtration and electrostatic precipitation actually worsened the allergic reaction.

Researchers determined that the problem is that the filtered, particle-depleted diesel exhaust is enriched with NO2. Those participants, who were genetically susceptible to oxidative stress, suffered the most, but all of them could forcibly exhale less air in one second after breathing allergens with filtered exhaust gas. Interestingly, scientists also observed an increased level of white blood cells, which suggests that play a meaningful role in eliciting a reduction in lung function. This could be worth revisiting in the future studies. But the question about the implications of this study remains to be answered.

So what do we do? People who suffer from lung-impairing allergies should probably avoid diesel cars. But we cannot stop filtering diesel exhaust. This probably means that our perceived solutions to diesel pollution are not that great and an outright reduction of diesel cars and trucks is a better way to go.

 

Source: University of British Columbia


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