Goethe University Frankfurt

In September 2020, two archaeologists, Rupert Gebhard from the Bavarian State Archaeological Collection in Munich, and Rüdiger Krause from the Goethe University Frankfurt/Main, expressed doubts that the world-famous Nebra sky disk, part of the UNESCO Memory of the world register, which is assumed to be the oldest concrete depiction of the cosmos, really is 3.600 years old, as stated by the state archeologist of Saxony-Anhalt.

Gebhard and Krause claim, that the sky disk is about a thousand years younger and thus from the Iron Age, not the Bronze Age. A research group, consisting of thirteen scientists, now has found more evidence, that the original dating was correct and therefore the doubts are unsubstantial.

An experimental study found that installing four commercial air purifiers in a classroom reduces aerosol concentrations by 90%. The team around Joachim Curtius of the Experimental Atmospheric Research Group of the Goethe University Frankfurt used one H13 filter in each of the devices, which can filter particles in a size of 0.1 particles in a size of 0.1 µm to 0.3 µm from the air.

Respiratory viruses such as SARS-CoV2 are transmitted by droplet infection, touch and aerosols. Air filters can serve as a protective measure against aerosols that are incompletely retained by masks.