Over the past few years, the impacts of carbon dioxide on our bodies - and especially our brains - have seen a lot of attention through a range of studies. However, a 2013 study has taken a different approach by looking at the cost-benefit of schools that provide adequate ventilation.

The study was carried out in elementary schools in California, with a total of 28 schools across three school districts (South Coast, Bay Area and Central Valley) being studied. Across these 28 schools, 162 3rd-5th grade classrooms were used for data to compare ventilation rates and illness absence.

The relationship between these rates - ventilation and illness absence - was estimated using real-time carbon dioxide measurements taken within each classroom. While carbon dioxide itself may not have caused all of the absences, it’s an excellent way to measure ventilation and also acts as a proxy for other airborne sicknesses, which may lead to absence.

All of the classrooms studied had ventilation rates below the California standard of 7.1 litres per second per person. Considering that each litre per second of increased ventilation led to 1.0 - 1.6% illness absence, the importance of adequate ventilation in classrooms is clearly highlighted in this study.

With this data, if classrooms were to increase ventilation rates to the state standard (7.1 l/s per person), illness absence would decrease by 3.4%. In turn, this could increase school attendance-linked funding by $33 million annually. While the study doesn’t go further, it mentions that further increasing ventilation rates could carry further benefits. 

Studies such as this continue to highlight the importance of indoor ventilation. Although this study was published before COVID-19, increasing ventilation levels can likely further decrease illness absence nowadays as carbon dioxide concentrations can act as a proxy for COVID-19 transmission chance.

If you would like to read the complete study, please refer to this link.