You are locked up with coworkers in a boardroom for two hours, making a plan. Risks are weighed, decisions are made. Then, as you emerge, you realize that it was much, much hotter and stuffy in there than in the rest of the office.
Small rooms can build up heat and carbon dioxide from our breath, along with other substances, to a point that you might be surprised by. And in this case, a small body of evidence suggests that when it comes to making decisions, indoor air may matter more than we thought.
At least eight studies over the past seven years have looked at what specifically happens in a room that accumulates carbon dioxide, a main ingredient in our exhalations. While the results are inconsistent, they are also intriguing.
They suggest that while the types of air pollution known to cause cancer and asthma remain much more urgent as public health concerns, there may also be pollutants whose most damaging effects are on the body. mind rather than body.
So, can you trust the decisions made in small rooms? How does indoor air quality affect your cognitive abilities? And as our knowledge of the effects of indoor air increases, do we need to rethink the way we design and use our buildings?
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It’s hot in here ?
In the United States, buildings have become increasingly airtight over the past 50 years, resulting in reduced energy consumption for heating and cooling. It also facilitated the build-up of gases and other substances released by humans and our property inside.
Although indoor air quality is not as well monitored as outdoor air, scientists and ventilation professionals have widely monitored carbon dioxide inside.
Higher CO2 levels – say, greater than 1,200 parts per million (ppm) – often indicate poor ventilation. Worrying substances emitted by new furniture, office supplies and rugs could build up in the air.
“This has long been considered an indicator of the quality of the air in a space,” said Brent Stephens, professor of architectural engineering at the Illinois Institute of Technology.
While other indoor air pollutants can be linked to respiratory problems and cancer, carbon dioxide itself is generally considered harmless at these levels. But researchers have started to reexamine this hypothesis.
Biomedical researchers have found that inhaling carbon dioxide at levels much higher than one might imagine in a workplace dilates blood vessels in the brain, reduces neural activity, and decreases communication between people. regions of the brain.
But how much smaller amounts, like those commonly found inside, could affect the brain has not been much studied.
About ten years ago, William Fisk, a mechanical engineer at Lawrence Berkeley National Laboratory, and his colleagues placed people in rooms where carbon dioxide levels varied.
They exposed subjects for hours to concentrations as low as 600 ppm, low enough for indoors and as high as 2,500 ppm – a high but not astronomical amount that is probably not uncommon in crowded spaces. Carbon dioxide levels in some classrooms can be twice as high, Fisk noted. in a later article.
The scientists took their subjects a problem-solving test measuring productivity and decision-making skills in the real world, said Usha Satish, professor of psychiatry at SUNY Upstate Medical University and co-author of the research.
The test generates scores for large attributes as the basic strategy and initiative. The team found a strong relationship between seven of the nine rubrics they looked at and carbon dioxide levels.
The higher the carbon dioxide, the worse the people tested; at 2,500 ppm, their scores were generally much worse than 1,000 ppm.
“It’s a very, very well designed study, with control for everything,” said Pawel Wargocki, professor of civil engineering at the Technical University of Denmark. “They were very, very careful with the details of the design.”
Other scientists who read the study were interested in the subject. A team led by Harvard researchers published similar results in 2016.
They had office workers come to a fictitious workplace for six days and take the same type of problem-solving test while being exposed to various concentrations of carbon dioxide and volatile organic compounds commonly found in apartment buildings. offices.
As carbon dioxide levels fell from 550 ppm to 945 ppm to 1400 ppm, subjects’ scores under most headings dropped significantly. (Problem-solving ability also seemed to suffer as VOC levels increased.)
“What we saw were these striking and really quite dramatic impacts on decision-making performance, when all we did was make some minor adjustments to the air quality in the building,” said Joseph Allen, a professor at the Harvard TH Chan School of Public Health who led the study.
“It is important to note that this was not a study of unique and exotic conditions,” he added. “It was a study of the conditions that could be achieved in most, if not all, buildings.”
Not all studies aimed at verifying the relationship between indoor carbon dioxide and cognition find a clear effect. Several studies using simpler tests of cognitive ability, such as proofreading a text, have not shown such a change.
Two studies using the same more complex test on submarine crews and people believed to be representative of NASA’s astronaut corps also did not reveal a link, Dr Wargocki said.
This does not mean that the studies that documented an effect were wrong. It might be easier to compensate for mental blurring on the simpler tests.
Or there may be an interaction between the stress of taking the more complex test – which takes the form of a simulation in which subjects have to use judgment and move quickly – and higher carbon dioxide levels that result in lower scores.
So far, studies haven’t measured subjects’ stress levels or taken other readings that might help explain why carbon dioxide only sometimes affects cognition. Submarine crews and astronauts are trained to make decisions under stress and can function normally under conditions that would disturb others.
What you can do
The question really is, what causes this effect and under what circumstances Dr Wargocki appears.
The fact that some people have difficulty thinking while breathing moderate levels of carbon dioxide suggests that it may be useful to take a closer look at the levels in offices and schools.
“In a study we did in a classroom, we consistently found high levels of CO2 over 1000 ppm over the course of an hour,” said Shelly Miller, professor of environmental engineering at the University of Colorado Boulder.
Numerous studies have also shown that increasing the ventilation rate in schools can increase children’s test scores and task speed, and reduce absences.
What the researchers found in the classrooms might be instructive for small conference rooms at work where we exchange ideas and plans. None of these studies specifically examined such spaces.
But variations in performance at different ventilation levels suggest that a generally recommended minimum airflow for a conference room, which is 6 cubic feet per minute per person, may not be optimal, Dr Allen said.
Without a specialized sensor, you can’t realistically know how much carbon dioxide is building up as you settle into a small room for a long meeting. It may generally be advisable to open a door (or a window when possible, and when outdoor air pollution is not a major concern). Letting in some fresh air can even help get some good ideas flowing throughout your meeting and keep the discussion from getting too stale.