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Benjamin Franklin once professed, “I am persuaded that no common air from without is so unwholesome as the air within a close room that has been often breathed and not changed.” 250 years on and modern science is successfully proving that founding father’s idea. A recent pair of harvard studies has given further credence to the theory that clean air makes us more productive.

Joseph Allen, assistant professor and director of Harvard’s Healthy Buildings program, along with his colleagues Jack Spengler and Piers MacNaughton, and collaborators Suresh Santanam at Syracuse University and Usha Satish at SUNY Upstate Medical, investigated this long held theory. For the first phase of their study, they enrolled 24 “knowledge workers,” that is managers, architects, and designers, to spend six days, over a two-week period, in a highly controlled work environment at the Syracuse Center of Excellence.

Each day they requested participants go about their normal work routine from 9am to 5pm. The researchers then changed the air quality conditions of their workspaces from a conventional environment, which hit the minimally acceptable standards, to an optimized one, which doubled those minimum ventilation rates. They also changed the level of volatile organic compounds by controlling the materials in the space and tested three levels of carbon dioxide, a key issue in the air quality – productivity debate.

“Typical outdoor CO2 concentrations hover around 380 parts per million (ppm), but studies have discovered that CO2 concentrations within offices are often as high as several thousand ppm,” states the extensive Environmental Controls section of our recent Future Workplace report. While “classrooms concentrations of CO2 have shown to consistently exceed 1000ppm and occasionally exceed 3000ppm, surely having a significant impact on the education of future generations,” we reported in an article on the topic.

By using the controlled environment to keep all other variables constant the researchers working on the Harvard study were able to isolate these specific factors. Then, at the end of each day, they tested the workers’ decision-making performance using a standardized cognitive function test that researchers have used for decades. Their results were clearer than they might have expected.

“We found that breathing better air led to significantly better decision-making performance among our participants. We saw higher test scores across nine cognitive function domains when workers were exposed to increased ventilation rates, lower levels of chemicals, and lower carbon dioxide,” said Joseph Allen, the principal investigator of the CogFx Study.

“The results showed the biggest improvements in areas that tested how workers used information to make strategic decisions and how they plan, stay prepared, and strategize during crises. These are exactly the skills needed to be productive in the knowledge economy,” Allen continued, underlining the importance of this research.

To limit the potential for bias, the team ran the experiments as a double-blind study. Both the participants and the researchers were unaware of the conditions in the space at any given time. In addition, they controlled for differences among the participants and measured each individual’s performance against their own baseline. “We didn’t care if one person was smarter than another; we were interested in how people compared against themselves,” Allen said. “Our results were consistent, indicating that there were no learning effects and that the blinding was effective.”

In the second phase of the study, the team moved out the lab and into the real world, so they could better test for additional ‘real world’ factors. This time they recruited more than 100 knowledge workers in 10 buildings located in varying climates across the US. They measured the indoor air quality in each of these buildings, six of which had held ‘green certification,’ and tested workers’ cognitive function again.

Controlling for factors such as salary, type of work, building owner/tenant, and geographic location, the researchers found that workers in buildings that were green certified scored higher on the tests. Beyond air quality, they also saw that temperature had a significant impact on productivity. When working under a standard comfortable temperature and humidity range, participants performed better on the tests of decision making, independent of which building they were in.

“Traditional building regulations have led to well-insulated office spaces, reducing temperature fluctuations but also reducing fresh air circulation,” we explained in our recent comprehensive report on The Future Workplace. The report deeply explores smart environmental controls and other modern concepts that are demonstrating clear advantages to health and productivity at the workplace.

So what should leaders and building managers take away from the findings of this and similar studies on the topic of indoor air quality? “The short answer is that better air quality in your office can facilitate better cognitive performance among your employees,” stated Allen. “While cost may be a concern, it turns out that the cost of improving air quality through higher ventilation rates are far lower than is widely believed,” he added.

By modelling the costs of four different types of ventilation system within different climate zones and from varying energy sources, Allen and his team estimate that the cost of doubling ventilation rates would be less than $40 per person per year. “In most cities, it’s even lower. When energy-efficient ventilation systems are used, the cost would be $1–$10 per person per year,” he said.

They also estimated that the productivity gains from doubling the ventilation rates would add up to $6,500 per person per year. A figure that does not include the other potential health benefits, such as reduced “sick building syndrome” and absenteeism. An older study, by Milton DK. et al., compared employee absenteeism in offices with varying air quality conditions. They found that short term sick leave was found to be 35% lower in offices ventilated by an outdoor air supply rate of 24 l/s compared to buildings with rates of 12 l/s.

“We’ve all struggled to concentrate in a conference room that is stuffy and warm. When a window or door is opened and fresh air comes in, it breathes life into the room. Businesses would benefit from recognizing this and taking action to optimize their air quality for employees’ health and productivity,” Allen concluded.

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  • Hermione Crease

    This looks like a pretty robust bit of research. Is there a direct link?

    We’ve been generating and analysing environmental data for a number of customers which confirms that CO2 levels in average commercial buildings can get surprisingly high. They are also quite transient and can concentrate in small spaces, meaning it’s useful to understand the interaction between staff occupation and ventilation rates. Might explain the old rule of thumb about the more people in a meeting, the less productive it is!