• Project number: F 2527
• Institution: Federal Institute for Occupational Safety and Health (BAuA)
• Status: Completed Project

Description:

During the Corona pandemic, the spread of virus-contaminated aerosols also gained importance in workplaces outside the medical-biological field. For multi-occupied rooms, knowledge of possible situation-related hazards was needed in order to be able to derive indications of suitable protective measures for operational practice. In this cooperation with the TU Dresden, program systems and models for the numerical simulation of indoor air flow, indoor air technology and particle dispersion were used for this purpose. By integrating existing approaches to the probability of infection by aersosol-bound SARS-CoV-2, reliable findings were obtained on the quantitative classification of exposure scenarios typical for practice and on the effectiveness of common ventilation and air purification methods.

Particularly for larger rooms, it was shown that possible virus contamination of indoor air can be kept to a minimum by sufficient air exchange in accordance with the Technical Rules. The natural thermal buoyancy on the human body supports the upward removal of aerosols from the head area. Aerosols released during breathing and speaking are removed most effectively if uncontaminated air flows in at low velocity and lower temperature in the floor area and contaminated air is extracted in the ceiling area. Displacement ventilation systems are ideal for this purpose. So far, they have been used primarily in large event rooms and lecture halls.

Mobile air purifiers work on a different principle: they usually draw in the room air in the floor area and are only of limited use. If the room is ventilated adequately, additional air cleaners do not have any relevant positive effect. If the air is blown out in an unfavorable direction, they may even promote the transmission of aerosols to other people. In the case of limited ventilation possibilities, properly used air purifiers with a sufficiently high air flow rate can reduce the aerosol load of the room air to a similar level as ventilation, but with somewhat greater local differences and without removing CO₂. For rooms with high occupancy/carbon dioxide release, air purifiers are therefore not an adequate substitute for sufficient ventilation.