Dispersion and Sedimentation of Airborne Particles and Germs in Laminar and Turbulent Airflow

Several studies have shown that the lowest concentrations of contamination in operating theatres are achieved by using fabric covered laminar airflow systems. These systems are distinguished due to the low turbulence intensities in the protective areas. An examination in a special designed test facility was done to get further information about the relation between the turbulence intensity and airborne contaminations. In a first stage the dispersion of airborne contaminations was examined. The measurements showed that because of variations in the airflow airborne contaminations can reach areas cross the main flux far away from their point of emission. The cross diffusion and the area in  which the particles and germs are spread is reduced in a less turbulent flow. In a second stage the sedimentation of germs under the influence of the turbulence intensity was examined. The measurements showed that a reduction of the turbulence intensity of 20% to 1 % (laminar flow) halves the sedimentation rates of the germs. Reducing the turbulence intensity leads to lower contamination of the ambient air at the wound site and lowers the chance of sedimentation. In conclusion the incidence of infection can be reduced.