An in-depth US-commissioned study has found that the air quality in an office can have a significant impact on the cognitive ability of the people who work there.
The year-long research by scientists at the Harvard TH Chan School of Public Health, Boston, examined 300 office workers in six countries including the UK, in fields such as engineering, property investment, architecture and technology.
It revealed that higher concentrations of fine particulate matter in the air and lower ventilation rates were linked with slower response times and reduced accuracy in cognitive tests.
The study investigated a type of pollution known as PM2.5, which consists of particles less than 2.5 micrometres long and is thought to be particularly damaging to health. It also looked at levels of carbon dioxide, which increase in poorly ventilated spaces.
Jose Guillermo Cedeño Laurent, a research fellow in the Department of Environmental Health and lead author of the study, said the impact on cognitive function of the pollution was serious. “Our study adds to the emerging evidence that air pollution has an impact on our brain. The findings show that increases in PM2.5 levels were associated with acute reductions in cognitive function. It’s the first time we’ve seen these short-term effects among younger adults,” he said.
Carbon dioxide was also responsible for slow mental response times.
Tests based on colour recognition showed that responses were slower and accuracy fell as PM2.5 and carbon dioxide levels increased. Arithmetic-based tests were also used. These found that increases in carbon dioxide but not PM2.5 were associated with slower response times. As concentrations of both pollutants increased, however, participants completed fewer questions correctly in the allotted test time.
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Researchers studied more than 300 office workers in cities across the US, China, India, Mexico, Thailand and the UK. Participants were aged 18 to 65 and worked at least three days a week in an office building.
Each participant’s workspace was fitted with an environmental sensor that monitored real-time concentrations of PM2.5 and carbon dioxide. Each person had a custom-designed app on their phones through which the cognitive tests and surveys were administered.
In the arithmetic test, response times increased by about 2% for every 500 parts per million rise in carbon dioxide levels. For the colour test, a rise in PM2.5 levels of 10 micrograms per cubic metre led to a 2% decrease in accuracy.
Cedeño Laurent said: “The study also confirmed how low ventilation rates negatively impact cognitive function. Overall, the study suggests that poor indoor air quality affects health and productivity significantly more than we understood.”
The findings chime with research carried out in academic settings by London School of Economics and others which found in 2019 that exam performance fell when air pollution rose. Israeli studies have shown similar results and in the US it was found that high levels of air filtration led to better academic performance.
Joseph Allen, senior author of the Harvard study said productivity and cognitive function were at stake unless buildigns were made healthier. “The world is rightly focused on Covid-19, and strategies like better ventilation and filtration are key to slowing infectious disease transmission indoors.
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“Our research consistently finds that the value proposition of these strategies extends to cognitive function and productivity of workers, making healthy buildings foundational to public health and business strategy moving forward.”
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