November 9, 2015

Link between “green” office environments and cognitive function

At a Glance

  • Office workers scored higher on performance measures when working in “green” environments with low indoor pollutants and low carbon dioxide levels.
  • The findings suggest that improving indoor air quality in office environments may increase the performance of office workers. 
Office workers walking in front of large windows with a view of outdoor gardens. Research suggests that improving indoor air quality can affect the job performance of office workers. hxdbzxy/iStock/Thinkstock

Most people typically spend about 90% of their time indoors. The quality of the indoor environment may affect both health and productivity.

In the 1970s, office buildings in the U.S. were constructed to be airtight and energy efficient due to the increased cost of energy. This resulted in decreased outdoor air ventilation, which can increase levels of indoor pollutants. Conventional buildings are now designed to be even more energy-efficient, raising the potential risk of building-related illnesses. More recent “green” standards are designed to be energy efficient but also improve indoor environmental quality by improving ventilation, filtration, and lighting, and by controlling indoor pollutant and chemical sources.

A team led by Dr. Joseph Allen at the Harvard T.H. Chan School of Public Health examined the impact of ventilation, chemicals, and carbon dioxide on cognitive function, an objective measure of productivity. The study was funded in part by NIH’s National Institute of Environmental Health Sciences (NIEHS). Results appeared online on October 26, 2015, in Environmental Health Perspectives.

The researchers recruited 24 participants—including architects, programmers, engineers, and managers—to work in cubicles in an office setting located in an environmental laboratory at Syracuse University. The scientists altered air quality to create 5 conditions: simulated conventional office building (with high levels of volatile organic compounds, or VOCs), simulated green office building (low VOC levels), simulated green-plus building (with a higher outdoor air ventilation rate), and 2 artificially elevated levels of carbon dioxide independent of ventilation.

The professionals performed their normal work activities from 9 a.m. to 5 p.m. for 6 days over 2 weeks (Tuesday through Thursday). The participants were “blinded” to the environmental conditions. At the end of each day, they completed a cognitive assessment, which measured their ability to process complex information and make decisions. The analysts were also blinded to the environmental conditions.

The researchers found that participants scored more than 60% and 100% higher on the days they were exposed to the green and green-plus conditions, respectively, compared to the conventional building condition. They also found declines in cognitive function when carbon dioxide concentrations were increased to levels that are common in indoor spaces.

“These results suggest that even modest improvements to indoor environmental quality may have a profound impact on the decision-making performance of workers,” Allen says.

Assessments in actual office environments will be important to confirm these findings. The results suggest that exposures in other indoor environments, such as homes, schools, and airplanes, may also merit investigation.

—by Carol Torgan, Ph.D.

Related Links

References: 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. Allen JG, MacNaughton P, Satish U, Santanam S, Vallarino J, Spengler JD. Environ Health Perspect 2015 Oct 26. [Epub ahead of print]. PMID: 26502459.

Funding: NIH’s National Institute of Environmental Health Sciences (NIEHS) and United Technologies.