Bio-based aviation fuel reduces the number of ultrafine particles that are emitted from the aircraft engines, thereby improving air quality. This is one of the conclusions drawn from a large-scale international study using a SAS aircraft at Copenhagen Airport. Researchers measured an aircraft with 34 percent bio-based fuel (known as Sustainable Aviation Fuel, SAF), in the tank while it was taxiing between the runway and the gate at the airport. Ground measurements show a reduction in the emission of ultrafine particles by about 30 percent. (....)