The tiniest are the nastiest: ultrafine particles and asthma

We cannot see, taste or smell ultrafine nanoparticles but their presence play a big role in our health, especially for those who suffer from asthma. This is according to a recent report from researchers at the University of California at Los Angeles (UCLA).

Asthma is a chronic inflammatory disease of the small airways in the lung. Asthma episodes are characterized by tightening of the airways that results in difficulty of breathing and wheezing. In the US alone, about million people are suffering from asthma and a large fraction of these are children.

Previous studies have shown that bigger particles can trigger asthma attacks but less is known about the effect of smaller traffic-generated particles. This is the first study to investigate fine particles.

So far, the smallest air pollutants measured have the diameter of 180 nanometers – about one-thousandth the size of a human hair. Thee minute particles are generated by traffic emissions with the highest concentrations measured along freeways and motorways.

Using a real-time testing method, the researchers tested the effect of these particles on the immune response in the lungs of lab animals. Their results indicate that nanoparticle exposure even for just a short while plays a major role in asthma flare-ups.

“The immune processes involved in asthma, and current treatments, are traditionally thought to be dominated by a specific initial immune response, but our study shows that ultrafine pollution particles may play an important role in triggering additional pathways of inflammation that heighten the disease.”

In fact, ultrafine particles may actually be more damaging than bigger particles. So what makes these minute particles so harmful?

“Pollution particles emitted by vehicles and other combustion sources are coated with a layer of organic chemicals that can be released into the lungs. These chemicals generate free oxygen radicals, which excite the immune system in the lung through a cell- and tissue-damaging process known as oxidation. Oxidation contributes to allergic inflammation in the lungs of people with asthma… Because of their size and large surface area, ultrafine particles have the capacity to carry and deposit a rich load of active organic chemicals deep in the lung. The chemicals coming off the particles in the small airways in the lung promote oxidative stress at those sites.”

The study results highlight the adverse effects of traffic pollution, especially on residents of urban areas and in the vicinity of freeways.