Although we already knew that particles dispersed in the atmosphere, with sizes of a few microns, can be harmful to health, a recent combination of analytical methods to determine their composition have shown that they can be even more dangerous than previously thought.
Air quality is related to suspended particles in the atmosphere. Image credit: pixabay.com.
A group of researchers from the Paul Scherrer PSI Institute have succeeded in observing for the first time the reactions that occur in these tiny particles floating in the air, and in doing so, they discovered that through photochemical processes oxygen radicals are produced that can be harmful to health. The results of this research were recently published in the journal Nature Communications.
We are aware that particles in the air pose a danger to human health; those that are only a few microns in size can penetrate and accumulate in lung tissue, and also contain radicals that can damage cells. These particles get into the air due to smoke from factories and vehicular traffic. But until now, from previous research it was known that these particles when absorbed in the respiratory tract form oxygen radicals, as they exchange oxygen with other molecules forming more reactive compounds such as hydroxyl radicals or methyl radicals produced from particles produced by combustion sources; these compounds cause oxidative stress in other molecules, to which medical experts attribute respiratory diseases such as asthma and pneumonia.
Looking inside the particles
But in previous studies these particles have been examined by mass spectrophotometry to know what they are composed of, and this technique does not provide information about the individual structure of the particles and the processes occurring inside them.
But in this study, thanks to the bright light of X-rays, it was possible to observe these particles individually with a resolution of less than one micrometer, using a triad of photochemical experiments to observe cycles of chemical reactions at the nanoscale inside the particles. These experiments included a combination of high-resolution X-ray microscopy techniques in addition to a single-particle electrodynamic balance.
Suspended particulates are due to both natural sources and emissions from combustion sources. Image credit: pixabay.com.
The researchers analyzed particles from natural sources such as desert dust and volcanic ash, as well as those from industrial emissions and traffic, finding that in the atmosphere the components of these particles combine to form iron complexes that then form dangerous radicals under the action of sunlight, which in turn form reactive oxygen species.
This information is very important because it allows scientists to better understand how airborne particles affect people's respiratory health, but it also makes it necessary to reformulate the models and control parameters regarding air quality, having to include a new factor that helps protect people from critical levels of certain airborne particles that induce the development of respiratory diseases.
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