covid-19

The COVID-19 pandemic increased the awareness and importance of infectious pathogens as contaminant in the indoor air, especially for non-residential buildings with a high occupational density like schools. During the COVID-19 pandemic air cleaning is often proposed as mitigation strategy for infectious risk in these types of buildings. However, indoor air quality (IAQ) in general comprises of a large range of possible contaminants and factors that can equally impact the health, comfort and well-being of occupants.

Coughing is one of the most important respiratory activities for air transmitted pathogens. It is essential to understand the dispersion of exhaled particles when coughing to improve the prevention measure and reduce the cross-infection risk. However, cough flow structure is complex and influenced by many parameters. Simplifications are often made to the initial flow condition when simulating the transport of particles expelled during coughing in laboratory or numerical studies .

Sufficient ventilation in clinics is critical for diluting virus concentrations and lowering subsequent doses inhaled by the occupants. Several advanced simulation methods and tools for building physics and indoor air fluid dynamics are currently available in research and industry. However, in naturally ventilated buildings, indoor air distribution depends strongly on local and dynamically changing conditions, e.g., opening sizes and time, exhaust shaft location, and climatic and weather conditions.

The University of Colorado Boulder (CU Boulder) is in Boulder, Colorado USA at 5280 feet above sea level. The campus has approximately 12 million square feet of infrastructure spanning over 100 years of building infrastructure evolution. In response to the COVID-19 pandemic, the University employed a science-based approach with campus researchers including aerosol scientists and campus epidemiologist and industry standards to inform a layered risk management strategy for an on-campus learning experience during the pandemic.

The ongoing covid-19 pandemic has drawn the attention on the importance of providing adequate fresh air to the occupants of the built environment, in particular in educational buildings. Higher ventilation rates and personal protection devices like facial masks are among the strategies and procedures to reduce the infection risk, allowing the fruition of school spaces despite the epidemic progression. Nevertheless, the problem of airborne transmission has been usually dealt with considering each environment alone and assuming steady state conditions.

The COVID-19 pandemic has prompted huge efforts to further the scientific knowledge of indoor ventilation and its relationship to airborne infection risk. Exhaled infectious aerosols are spread and inhaled as a result of room airflow characteristics. Many calculation methods and assertions on relative airborne infection risk assume ‘well-mixed’ flow conditions.

Schools had covered special attention in the last year, due to their importance to organize daily work as well as since most of the children were still not vaccinated. Under this circumstance, the importance of air renewal to reduce the probability of COVID-19 contagion inside buildings was highlighted. 

The Airborne Infection Reduction through Building Operation and Design for SARS-CoV-2 (AIRBODS ) project aim is to deliver guidance on the ventilation operation and future design of non-domestic buildings and to quantify the risk of, and reduce the transmission of SARS-CoV-2 in buildings. It is doing this through experimentation, computer simulation and fieldwork supporting the guidance and tools.

There is large amount of research on COVID-19 infections including the spread and removal mechanisms of the virus in indoor spaces. Ventilation, air cleaning and air disinfection are the main engineering measures to control the virus spread in buildings. Wells Riley model allows to calculate the infection risk probability for any airborne virus aerosol-based transmission, but this calculation is overcomplicated in the ventilation design because of large amount of input data needed that is not easy to understand to ventilation designers.