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CO2 and Cognition

Satish and Allen's dose-response curves for indoor CO2.

Indoor CO2 above 1000 ppm measurably impairs strategic thinking within an hour of exposure.

Outdoor CO2 sits around 420 ppm. Indoor CO2 rises as humans breathe and falls as ventilation replaces it. Two landmark papers — Satish 2012 and Allen 2016 — showed that above 1000 ppm, cognitive performance on specific tasks (strategic thinking, crisis response, information use) declines measurably. By 2500 ppm, performance on those tasks is cut by 60-80%.

Quick answer

Indoor CO2 above 1000 ppm measurably impairs strategic thinking within an hour of exposure.

What you are trying to do
Satish and Allen's dose-response curves for indoor CO2.
Best next step
CO₂ Cognitive Tax
Limit to remember
Treat this as a practical aid for the task, not a replacement for professional judgment.

Key points

  • ▸ Outdoor baseline: ~420 ppm, rising globally about 2 ppm per year.
  • ▸ Satish 2012: at 1000 ppm, strategic thinking drops 11-23% vs 600 ppm baseline; at 2500 ppm, drops 44-94%.
  • ▸ Allen 2016: replicated under more realistic office conditions with similar magnitude.
  • ▸ ASHRAE target: indoor CO2 below 1000 ppm. Actual measured office CO2 in poorly ventilated buildings: 1200-2500+ ppm.
  • ▸ Effect is reversible within minutes of ventilation — open a window and cognition returns to baseline.

Examples

  • Bedroom at dawn
    Closed door overnight, two occupants. CO2 often 1200-1800 ppm by morning. First-hour cognition is measurably impaired.
  • Meeting room with 6 people · no ventilation
    CO2 climbs from 420 ppm at entry to 1800+ ppm within 45 minutes. Decision-making degrades through the meeting.
  • Home office with door closed
    900-1400 ppm typical. A $50 CO2 monitor reveals this; most people are surprised at the number.

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Frequently asked questions

› Are the Satish/Allen results replicated?

Partially. Some replication studies find smaller effects; others find none under specific task designs. The effect is real but magnitude varies by task type — strategic/complex tasks show decline, simple reaction-time tasks often do not.

› Why does CO2 affect cognition if I am not hypoxic? Troubleshooting

Mechanism is still debated. Leading hypothesis: cerebral vasoconstriction from mild hypercapnia, plus acid-base shift. Not oxygen deprivation — CO2 at 2500 ppm is far below any hypoxic threshold.

› How should I use this guide with a Kefiw tool? How-to

Use the guide as the plan and the linked Kefiw tool as the check. Read the steps first, try the move manually, then use the tool to compare outputs, catch edge cases, and decide whether the result actually fits your task.

› What mistake do tool guides help avoid? Troubleshooting

Tool guides help avoid using a utility mechanically without understanding what you are trying to accomplish. Most word, writing, and text utilities are fast, but speed can hide context mistakes. Know whether you are solving a puzzle, cleaning copy, drafting a line, or checking a rule.

› Can a tool guide help me learn the skill? How-to

A tool guide can help you learn if you pause before accepting the output and ask why it worked. Compare your first guess with the tool result, look for the rule or pattern, and repeat that review. Passive copying solves one task; active review builds the skill.