A stuffy meeting room can hurt your thinking

15 Sept 2026 · 1 min

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1:04

In this short monologue, the speaker explains that indoor carbon dioxide (CO₂) concentrations in closed conference rooms can rise dramatically when people are packed together, reaching 1,000–2,500 ppm—far above the typical outdoor level of 300–400 ppm. Citing research from Lawrence Berkeley National Laboratory, the speaker describes an experiment where participants spent 2.5 hours in a room set to different CO₂ levels and then completed decision‑making tests. At 1,000 ppm, performance fell by 11–23 %; at 2,500 ppm, scores dropped by 44–94 %. The author of the study called the effect “astonishing.” The speaker concludes that the mental fog felt during long meetings is likely due to poor air quality, not boredom, and recommends shorter meetings, fewer attendees, and periodic breaks outdoors to preserve cognitive function.

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A long meeting in a stuffy conference room literally makes you dumber. Not metaphorically, chemically. Outdoor air has carbon dioxide levels around 300 to 400 parts per million. But pack people into a closed meeting room, everyone exhaling, and CO2 can hit 1,000 or even 2,500 parts per million. Researchers at Lawrence Berkeley National Laboratory put subjects in a room for 2.5 hours at different CO2 levels and tested their decision-making. At 1,000 parts per million, performance on most tests dropped 11 to 23%. At 2,500 parts per million, decision-making scores fell 44 to 94%. One of the study authors called the effects so astonishing it was almost hard to believe. So that foggy feeling in 2-hour meetings isn't boredom. It's probably the air. So shorter meetings, fewer invitees, take some breaks outside, because the big decision you saved for the end of that 2-hour meeting is being made by the dumbest version of everybody in the room.