
New research has revealed that carbon dioxide, the gas we exhale in every breath, may significantly impair cognitive functioning when accumulated in indoor environments and the levels that prove dangerous may be much less than they had previously thought safe.
Researchers from Lawrence Berkeley National Laboratory in California tested 22 healthy young adults and found that performance on nearly 70% of the tests declined notably when indoor carbon dioxide levels were pushed to 1,000 parts per million (considered safe) from 600 ppm (considered very good). On all tests, performance fell when the levels were raised to 2,500 ppm. This is significant because 1,000 ppm of CO2, the level used in the study, used to be considered a benchmark of good ventilation.
Outdoor carbon dioxide levels are typically 350-400 ppm while indoor values of 600 ppm are considered “very good” but researchers noted that “there are plenty of buildings where you could easily see 2,500 ppm of CO2 — or close to it — even with ventilation designs that are fully compliant with current standards”.
Researchers explained that they never expected elevated CO2 levels as the culprit:
“We’ve seen higher CO2 levels associated with increased student absences and poorer performances on school-type tasks but we never thought CO2 was actually responsible. We assumed it was a proxy for other pollutants.”
The researchers said they had little doubt that given the current standards, there are likely plenty of school districts with CO2 levels of 2,500 ppm – far greater than the 1,000 ppm that triggered the limited cognitive functioning in their study.