SafeCar - Detecting the spread of Corona viruses in ambulances and eliminating them swiftly and efficiently

To prevent the spread of SARS-CoV-2, it is essential that infected individuals are isolated rapidly and effectively. However, the ambulance staff and the patients transported after infected cases face an acute risk because the number of special vehicles for transporting highly contagious patients is limited. Standard ambulances, on the other hand, do not have separately ventilated or segregated areas for isolating potentially infectious individuals. But how can the transmission of the virus via contaminated surfaces or infectious droplets (aerosols) be reduced?

The project centers around the rapid and effective elimination of viruses during transport and immediately afterwards. Environment, hygiene and sensor technology experts, as well as air conditioning specialists for airplanes and vehicles, analyzed the spread of viruses in ambulances in different ventilation and driving scenarios. To this end, the Bavarian Red Cross provided the scientists with an ambulance that was not in use at the time.

The studies used model viruses that are harmless to humans and similar in size and structure to the SARS-CoV-2 virus. The spread of the volume flows, model viruses and also of carbon dioxide (CO2) as an exhaled gas inside the ambulance was considered in different ventilation scenarios when the ambulance was stationary and on the move.

Over time, the virus particles introduced (to simulate a “breathing infectious patient”) underwent a change from isolated single viruses to agglomerated droplets. If no ventilation takes place, the concentration of viruses rises very quickly inside the vehicle. By switching on ceiling fans, their numbers drop significantly within a very short time. Air extraction proved to be much more efficient than ventilation because the viruses are extracted from the air immediately above potentially infectious patients. Otherwise, they are advanced into the interior of the ambulance and can also settle on surfaces to a certain extent.

In parallel, scientists at Fraunhofer IVV studied the use of a plasma technology for decontaminating ambulances effectively after an “infectious” trip. The results were combined in a final test campaign, in which possible secondary hazards - such as the formation of ozone - were also considered by Fraunhofer IBP.

• Fraunhofer Institute for Building Physics IBP
• Fraunhofer Institute for Process Engineering and Packaging IVV, Stuttgart
• Bavarian Red Cross