Hotel Milano Scala has recently installed a new Mitsubishi Electric filtration system. Fresh air entering the interior spaces is treated in four air handling units — three rated at 5,000 m³/h plus one at 10,000 m³/h for a total air treatment capacity of 25,000 m³/h — composed of a class G4 pre-filter and a class F9 final filter (the same ones used in hospitals to prevent contamination).