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Poor Air Quality Affects Cognitive Performance in the Office, Study Finds

drawing of people working in an office with poor air quality

Verywell / Madelyn Goodnight

Key Takeaways

  • Harvard researchers carried out cognitive tests on 302 office workers across six countries.
  • They found that poor air quality had critical consequences for employees' cognitive performance, such as response times and the ability to focus.
  • Employers need to make improving indoor office air quality a priority, say experts.


There’s plenty of research highlighting the dangers of exposure to outdoor pollution, but what about indoor life? A small number of studies on indoor settings have examined things like thermal comfort and satisfaction, but new research by Harvard scientists took a different approach.

Their study, published in Environmental Research Letters, found that the air quality inside an office can have critical consequences for employees’ cognitive function, such as the ability to focus and response times.

The Study in Detail

Lead author Jose Guillermo Cedeño Laurent, ScD, and his Harvard colleagues studied 302 office workers across six countries (China, India, Mexico, Thailand, the United States, and the United Kingdom), from March 2019 until the COVID-19 pandemic put much of the world under lockdown.

All employees were between 18 and 65 years and worked at least three days per week in an office building. They each had a permanent workstation, which was fitted with an environmental sensor as part of the study. This monitored real time concentrations of fine particulate matter 2.5 micrometers and smaller (PM2.5), plus carbon dioxide, temperature, and relative humidity.

The participants carried out cognitive tests on custom-designed smartphone apps, at prescheduled times or when the sensors detected PM2.5 and CO2 levels that fell below or rose above specific thresholds.

Huma Sheikh, MD

It intuitively makes sense that poor air quality would have an impact on the human body. This would make most sense for our lungs and breathing, but seeing that it can also then influence our thinking and focus is very important.

— Huma Sheikh, MD


The first cognitive test involved correctly identifying the color of displayed words that spelled out a different color. The purpose of this was to determine cognitive speed and the ability to focus on relevant stimuli when irrelevant stimuli was provided.

The second test required basic addition and subtraction with two-digit-long numbers, to judge cognitive speed and working memory.

Each interquartile (IQR) increase of PM2.5 was associated with a 0.82% increase in response time and a 6.18% increase in interference time. And in terms of C02, each IQR increase was associated with a 0.85% increase in response time and a 7.88% increase in interference time.

Improving Indoor Air Quality

“It intuitively makes sense that poor air quality would have an impact on the human body,” says neurologist and Verywell Mind review board member Huma Sheikh, MD. “This would make most sense for our lungs and breathing, but seeing that it can also then influence our thinking and focus is very important.”

So with COVID-19 restrictions easing around the world and millions of people are returning to in-person office work, how can employers improve indoor air quality?

Shaheen Lakhan, MD, PhD

Serious investment is needed in commercial buildings to improve ventilation, naturally through windows and doors, and mechanically through HVAC systems.

— Shaheen Lakhan, MD, PhD


“Serious investment is needed in commercial buildings to improve ventilation, naturally through windows and doors, and mechanically through HVAC systems,” says Shaheen Lakhan, MD, PhD, FAAN, neurologist and Verywell Mind review board member. He adds that surfaces should be cleaned using safe products, smoking banned, and HEPA filters operational covering the working area.

“It is important to have air quality measurements in the office taken regularly as well as make sure there is natural air circulation,” says Dr. Sheikh. “Poor air circulation has also been linked to headaches and other physical symptoms, so it’s important to not dismiss these issues if employees are noticing that they are having certain symptoms at work, and not during weekends or times when they are not in the office.”

What This Means For You

To maintain and improve cognitive health, start with the basics: diet, exercise, and maintaining close, healthy social relationships.

Keep the brain stimulated with challenging tasks and games like puzzles and Sudoku, and sustain cognitive health with good sleep habits. To reduce high stress levels, which can impact cognitive function, make healthy coping mechanisms like meditation and spending time in nature a priority.

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  1. Cedeño Laurent JG, MacNaughton P, Jones E, et al. Associations between acute exposures to PM2.5 and carbon dioxide indoors and cognitive function in office workers: a multicountry longitudinal prospective observational study. Environ Res Lett. Published online September 9, 2021. doi: 10.1088/1748-9326/ac1bd8