You're stuck with colleagues in a meeting room for two hours, hashing out a plan. As you emerge, you realize it was much, much warmer and stuffier in there than in the rest of the office.
Small rooms can build up heat and carbon dioxide from breath and other substances. A small body of evidence suggests that indoor air could affect the quality of decision making.
At least eight studies in the past seven years have looked at what happens specifically in a room accumulating carbon dioxide, a main ingredient in human exhalations. The results are inconsistent but intriguing.
They suggest that while the kinds of air pollution known to cause cancer and asthma are much more pressing as public health concerns, there could also be pollutants whose most detrimental effects are on the mind, rather than the body.
Can you trust the decisions made in small rooms? How much does the quality of air indoors affect cognitive abilities?
Buildings in the United States have become better sealed in the past 50 years, helping reduce energy used in heating and cooling. That has also made it easier for gasses and particulates released by humans and our belongings to build up inside.
TAKE A DEEP BREATH
Although indoor air quality is not as well monitored as the air outdoors, scientists and ventilation professionals have extensively monitored carbon dioxide indoors.
Higher CO2 levels — say, above 1,200 parts per million (ppm) — often indicate poor ventilation. Worrisome substances emitted by new furniture, office supplies and carpets could be accumulating in the air.
"It's long been thought of as an indicator of how bad the air in a space might be," said Brent Stephens, a professor of architectural engineering at Illinois Institute of Technology.
While other indoor air pollutants can be linked to respiratory problems and cancers, carbon dioxide itself generally has been considered harmless at these levels. But some researchers are re-examining that assumption.
Inhalation of carbon dioxide at high levels — much higher levels than you'd ever expect in a workplace — has been found by biomedical researchers to dilate blood vessels in the brain, reduce neuronal activity and decrease the amount of communication between brain regions.
But how lower amounts like those commonly found indoors might affect the brain has not been studied much.
About 10 years ago, William Fisk, a mechanical engineer at Lawrence Berkeley National Laboratory, and his colleagues put people in rooms where the carbon dioxide levels varied.
They exposed subjects for hours to concentrations as low as 600 ppm, fairly low 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 had their subjects take a problem-solving test that measured productivity and decision-making skills, said Usha Satish, a professor of psychiatry at SUNY Upstate Medical University and a co-author of the research.
The test generates scores for broad attributes such as basic strategy and initiative.
The higher the carbon dioxide, the worse the test-takers did; at 2,500 ppm, their scores were generally much worse than at 1,000 ppm.
"It's a very, very well-conceived study, with a control for everything," said Pawel Wargocki, a professor of civil engineering at Technical University of Denmark.
A team led by Harvard researchers published similar results in 2016. They had office workers come into a mock workplace for six days and take the same kind of problem-solving test while exposed to various concentrations of carbon dioxide and volatile organic compounds common in office buildings.
As levels of carbon dioxide rose from 550 ppm to 945 ppm to 1400 ppm, subjects' scores under most headings declined substantially. Problem solving also seemed to suffer as levels of volatile organic compounds rose.
"What we saw were these striking, really quite dramatic [effects] on decision-making performance, when all we did was make a few minor adjustments to the air quality in the building," said Joseph Allen, a professor at the Harvard T.H. Chan School of Public Health who led the study.
BREATHE OUT
Not every study that sets out to check the relationship of indoor carbon dioxide to cognition finds a clear effect. Several studies using simpler tests of cognitive ability, such as proofreading a text, have not shown such a shift.
Two studies using the same, more complex test on submarine crews and people meant to be representative of the NASA astronaut corps also did not turn up a connection, Wargocki said.
That doesn't mean the studies that documented an effect were flawed. It could be easier to compensate for mental fuzziness on simpler tests.
Or there could be an interaction between higher carbon dioxide levels and the stress of taking a more complex test — in this case a simulation in which subjects must use their judgment and move quickly — that results in lower scores.
So far, studies have not measured subjects' stress levels or taken other readings that could help explain why carbon dioxide only sometimes affects cognition. Submarine crews and astronauts are trained to make decisions under stress and might function normally under conditions that would perturb others.
WHAT YOU CAN DO
The question really is what is causing this effect, and under what circumstances does it appear, Wargocki said.
That some people have difficulty thinking while breathing moderate levels of carbon dioxide suggests it is worth taking a closer look at levels in offices and schools.
"In a study we did of a classroom, we consistently saw elevated levels of CO2 over 1,000 ppm over the course of an hourlong class," said Shelly Miller, a professor of environmental engineering at the University of Colorado at Boulder.
Many studies have found that increasing the ventilation rate in schools can raise children's scores on tests and speed at tasks, and reduce absences.
Without a specialized sensor, you can't realistically know how much carbon dioxide is building up while you hunker down in a small room for a long meeting. Would it hurt to crack open a door (or a window when possible, and when outside air pollution isn't a concern)? Letting some fresh air in might help to keep good ideas flowing and prevent the discussion from growing too stale.
Style on 05/27/2019