Key ideas
Core concepts
- Small controlled studies report lower scores on some decision-making measures at elevated CO₂ levels. This does not establish a universal classroom impairment threshold.
- Proper ventilation and air quality monitoring keep CO₂ within acceptable limits for learning.
Carbon dioxide (CO₂) is one indicator of indoor ventilation. Research links ventilation conditions with some cognitive and school outcomes, but mechanisms and effects vary across settings.
Connected to
Cognitive Load Theory | Attention | Temperature | Sleep
Research evidence
Satish et al. (2012) exposed 22 participants to 600, 1,000 and 2,500 ppm CO₂ under controlled conditions and found reductions on several decision-making scales. Allen et al. (2016) studied office workers. These experiments do not directly establish the effects on pupils’ mathematics learning or a universal threshold at 1,000 ppm.
Physiological mechanism
The cited studies do not establish oxygen deprivation as the mechanism at ordinary classroom CO₂ concentrations. CO₂ may also indicate inadequate ventilation and the accumulation of other indoor pollutants; separate these possibilities when interpreting an association.
Ventilation studies in schools report associations and intervention findings relevant to pupil performance (Haverinen-Shaughnessy et al., 2011, 2015; Bakó-Biró et al., 2012). They differ in design and do not establish identical effects in every classroom. Monitoring can inform building ventilation decisions (Wargocki & Wyon, 2017).
References
Satish, U., Mendell, M. J., Shekhar, K., Hotchi, T., Sullivan, D., Streufert, S., & Fisk, W. J. (2012). Is CO₂ an indoor pollutant? Direct effects of low-to-moderate CO₂ concentrations on human decision-making performance. Environmental Health Perspectives, 120(12), 1671-1677. https://doi.org/10.1289/ehp.1104789
Allen, J. G., MacNaughton, P., Satish, U., Santanam, S., Vallarino, J., & Spengler, J. D. (2016). Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: A controlled exposure study of green and conventional office environments. Environmental Health Perspectives, 124(6), 805-812. https://doi.org/10.1289/ehp.1510037
Wargocki, P., & Wyon, D. P. (2017). Ten questions concerning thermal and indoor air quality effects on the performance of office work and schoolwork. Building and Environment, 112, 359-366. https://doi.org/10.1016/j.buildenv.2016.11.020
Haverinen-Shaughnessy, U., Moschandreas, D. J., & Shaughnessy, R. J. (2011). Association between substandard classroom ventilation rates and students’ academic achievement. Indoor Air, 21(2), 121-131. https://doi.org/10.1111/j.1600-0668.2010.00686.x
Haverinen-Shaughnessy, U., & Shaughnessy, R. J. (2015). Effects of classroom ventilation rate and temperature on students’ test scores. PLoS ONE, 10(8), e0136165. https://doi.org/10.1371/journal.pone.0136165
Bakó-Biró, Z., Clements-Croome, D. J., Kochhar, N., Awbi, H. B., & Williams, M. J. (2012). Ventilation rates in schools and pupils’ performance. Building and Environment, 48, 215-223. https://doi.org/10.1016/j.buildenv.2011.08.018