How to see the invisible virus?

Did you know that in the global scale the biggest air pollution problems are caused by the particles? Many atmospheric gases (carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide) and solid and liquid particles (particulate matter, PM) are classified as hazardous air pollutants. They are invisible, yet we constantly breath them into our lungs. Air pollution kills around seven million people every year.

A simulation by Finnish Meteorological Institute (FMI). A modeling from a restaurant. The picture visualizes the aerosol concentration after 4 minutes of staying in the room. The darkest color corresponds to a 100 higher concentration than the lightest color. Those smaller than that are not shown at all. Picture: Mikko Auvinen

The aerosols we breath

During the last couple of years, we have all become unpleasantly aware of these invisible and dangerous particles (let’s call them aerosols) around us. We have heard that virus may be transmitted along with these aerosols, hiding among them. This imminent danger has motivated us to seek for protection.

We have been introduced with the use of personalized aerosol filters (face masks), safety distances, improved air ventilation, and other means to minimize our exposure to aerosols, basing on our understanding that they could potentially contain virus. The focus has been on one particular virus (let’s call it SARS-CoV-2) but at the same time we have learned to be cautious about aerosols, in general.

This coughing robot head is simulating the aerosols that human's produce while coughing. Read more about it here. Photo: Nea Alanen

The answers before the questions

It is not easy to imagine the presence of millions of invisible aerosols around us but there is also no reason for panic. The good news is that the scientists do not need to imagine the aerosols: we have been measuring them for decades already!

With the advancing technologies, nowadays, we can detect the existence of each individual aerosol particle. We have models that forecast their movements with the air. These tools were not developed to respond to the pandemic, but to better understand the role of aerosols for air quality and climate (which are still very relevant concerns, by the way). This is typical in science: develop solutions before knowing all the questions.

Invisible to visible

It is only quite recently that the broader scientific community has truly started to understand the important role that aerosols have in spreading the viruses. In E3 project the most advanced techniques to measure the (virus-)aerosols are taken in practice and further developed.

The movement of the aerosols is accurately measured and visualized with computer simulations. The experiments are taken in real world environments to seek for practical solutions to our everyday life. The previously invisible aerosols are now more visible than ever.

Eija Asmi & Hilkka Timonen

Researchers from the Finnish Meteorological Institute (FMI)

FMI simulation picture is related to this article.

More about the coughing head here.