In a study that is the first of its kind, researchers from the MIT Center for Real Estate Research and Maastricht University have linked increased CO2 concentrations in classrooms to a reduction in standardised test and exam results. 

The study was conducted across 216 classrooms in over 20 schools in the Netherlands. In total, these classes were attended by around 5,500 students during a period of five school terms from 2018 to 2020. 

The conclusion is perhaps not surprising but has finally been proven - exposure to poor indoor air quality before a test lead to significantly lower test results. In this case, a single standard deviation increase in the school-term average daily CO2 peak lead to a 0.11 standard deviation decrease in test results.

This study is particularly important, however, because it also accounted for other environmental factors that impact test scores. For example, particle air pollution, heat exposure, and school closings (interruptions to learning). Even with these factors considered, CO2 has a significant impact on test results.

While it wasn’t discussed in this study, it’s also been found that a higher daily average CO2 concentration in classrooms leads to increased absences over the course of a school term. This is particularly impactful because a higher number of days off per year is associated with lower overall grades too.

With more research discovering and explaining the impacts of carbon dioxide on our minds and bodies, it’s only a matter of time before CO2 monitors are required in more classrooms around the world.