Thinking beyond just health — the real effect of air quality on productivity.

From comfort to cognition: how air quality shapes productivity

Productivity is usually discussed in terms of people, processes, and skills. Rarely does the conversation start with the air itself. Yet a growing body of research suggests that what employees breathe each day has a measurable influence on how quickly they think, how accurately they work, and how well they perform.

Indoor air quality and wider indoor environmental quality are no longer just comfort or wellbeing topics. They are increasingly performance variables.

How does CO₂ affect productivity?

Carbon dioxide is not harmful at typical office levels, but it is an excellent indicator of how well a space is ventilated. When CO₂ rises, fresh air is limited, and the cognitive effects begin to appear.

In a year-long multinational study of more than 300 office workers, higher indoor CO₂ levels were linked to slower response times and reduced mental throughput, even though concentrations remained within ranges widely accepted for offices. Participants took longer to complete attention and arithmetic tasks and produced fewer correct answers per minute. In practice, poor ventilation quietly slows thinking long before anyone complains about stale air.

Fine particulates affect both accuracy and reaction speeds

Ventilation is only part of the picture. Fine particulate matter (PM₂.₅) plays an equally important role. The same study found that as PM₂.₅ levels increased, workers showed slower reaction times and lower accuracy, particularly once concentrations rose above 12 µg/m³, a level commonly found in urban indoor environments. Experimental studies reinforce this, showing overall task performance falling by around 1% for every 10 µg/m³ increase in PM₂.₅. These are not dramatic collapses in performance, but subtle degradations that eat away at a worker’s ability to think and work efficiently.

How is productivity actually measured?

What makes this evidence compelling is how performance was tested. Researchers did not rely on perception surveys or self-reported fatigue. Instead, they used established cognitive tools such as the Stroop colour–word test and timed arithmetic tasks. These measure attention control, processing speed, inhibition, and working memory, precisely the mental functions required for decision-making, analysis, and problem-solving in modern offices.

Ventilation and working faster

When ventilation improves, performance improves with it. A large meta-analysis covering 47 experiments and nearly 3,700 participants found that higher ventilation rates consistently produced faster task completion and lower error rates. Arithmetic performance improved by up to 14 % at higher airflow levels, with smaller but still meaningful gains for broader cognitive tasks. The strongest effects appeared in poorly ventilated spaces, suggesting that many buildings still operate below their cognitive optimum.

Why errors matter as much as speed

Productivity is often equated with output volume, but in most workplaces quality matters just as much. Poor air quality slows responses and increases the likelihood of mistakes at the same time. For roles involving design, finance, healthcare, or engineering, small increases in error probability can outweigh any gains in pace, increasing rework, review cycles, and operational risk.

What this means for real buildings

Ventilation rates, filtration efficiency, particulate control, and thermal stability are therefore not merely comfort settings. They are performance levers. Buildings that control CO₂ and PM₂.₅ effectively create conditions where people think faster, make fewer mistakes, and sustain concentration for longer. Over an entire workforce, even modest cognitive gains can translate into significant business value.

The evidence now points in a clear direction. Indoor air quality does more than protect health. It shapes how well people think and how effectively they work. In knowledge-driven organisations, investing in your air is more than just a compliance tick-list now; it can actually improve worker performance and increase both project accuracy and output.