Generally speaking, the settling velocity (the number of microorganisms that settle on a petri dish in a given time) of aerosols can vary greatly and depends on the particle type. The greater the settling velocity, the lower the risk of exposure to the operator. This is because the bigger the particle, the greater is the settling velocity and vice versa.
This means bioaerosols can potentially expose personnel in two different ways. To understand this, consider this: The human respiratory tract is as big as a tennis court. With every breath, millions of particles come into contact with our respiratory tract.
Some of the particles, especially the ones smaller than four micrometers, will gain access to lung tissue. And some can even reach our bloodstream. Ingestion and dermal contact is also possible with larger droplets that contaminate the surface of laboratory equipment and other surfaces in the lab.Very common laboratory activities produce aerosols, and we only mention a few of them in this text. Often, lab activities are carried out without even thinking about aerosols, but around the world there are many documented cases of laboratory-acquired infections resulting from the production and inhalation of infectious aerosols. In your daily laboratory work, centrifugation is just one source of aerosols, and you must take adequate precautions when working with infectious or harmful substances.
During centrifugation, aerosols can escape during the high-speed spin process, for example, if microorganisms are not adequately contained within the centrifuge. This may occur if you spin uncapped samples or if a tube leaks or breaks. In the following, we will provide some advice on minimizing aerosol production while centrifuging.
As a first step, make sure to choose the right centrifuge vessel and consider what precautions to take. The rotor plays an important role in preventing formation of aerosols outside the centrifuge. For this reason, you should know how to clean and disinfect the centrifuge and its accessories after a run and should there be leakage.