Evaluation of ventilation performance and compliance with Belgian covid-19 guidelines in sport infrastructure

During the corona-19 pandemic waves in 2020 and 2021, many cultural and recreational activities inside buildings could no longer take place to prevent virus transmission. In order to allow cultural and recreational sectors to reopen in a safe way by the summer of 2021, a ventilation task force of the corona commissioner's office of the Belgian federal government prepared recommendations for the practical implementation and monitoring of indoor air quality in the context of COVID-19. This implementation plan was conceived as an instrument for building owners or facility managers to evaluate whether existing ventilation facilities, possibly in combination with other technical measures such as opening of windows and doors, or air purification devices, would provide sufficient ventilation to allow a certain number of occupants in a room. 
In preparation of the resumption of indoor sports activities, a research consortium investigated the applicability and consequences of the federal guidelines specifically for sports infrastructures in Flanders, Belgium. To this end, various sports federations organized a number of test events in the first half of June 2021. The test events took place in four different indoor sports facilities, including fitness centres, a climbing gym and a sports hall, for varying group sizes of athletes and public. In preparation of the test events, the mechanical ventilation systems were inspected and installed ventilation flow rates measured. During the test events, CO2 measurements were carried out throughout the sports infrastructures, and the concentrations were permanently logged.  
This paper discusses the main results of the ventilation inspections, CO2 monitoring and subsequent analysis. By applying the recommendations of the implementation plan to the test events in sport, the paper further discusses the feasibility of implementing the plan in practice, what the consequences are for the maximum permissible occupation in sports halls (both for athletes and spectators), and provides guidelines on how the ventilation in existing infrastructure can be improved based on the findings.