Carbon Dioxide Comfort Levels

CO2 acceptance and comfort levels

Indoor air quality includes

  • temperature
  • odor
  • high or low levels of gases

Since CO2 is exhaled by people at predictable levels the content of Carbon Dioxide - CO2 - in air may be a significant indication of air quality.

A measure of CO2 indicates the amount of fresh air supply:

  • 15 cfm ventilation rate per occupant corresponds to 1000 ppm CO2
  • 20 cfm ventilation rate per occupant corresponds to 800 ppm CO2

Normal CO2 Levels

The effects of increased CO2 levels on adults at good health can be summarized:

  •  normal outdoor level: 350 - 450 ppm
  • acceptable levels: < 600 ppm
  • complaints of stiffness and odors: 600 - 1000 ppm
  • ASHRAE and OSHA standards: 1000 ppm
  • general drowsiness: 1000 - 2500 ppm
  • adverse health effects expected: 2500 - 5000 ppm
  • maximum allowed concentration within a 8 hour working period: 5000 ppm  

The levels above are quite normal and maximum levels may occasionally happen from time to time.

Extreme and Dangerous CO2 Levels

  • slightly intoxicating, breathing and pulse rate increase, nausea: 30,000 ppm
  • above plus headaches and sight impairment: 50,000 ppm
  • unconscious, further exposure death: 100,000 ppm

Carbon Dioxide Standard Levels

The recommendation in ASHRAE standard 62-1989 are

  • classrooms and conference rooms 15 cfm per occupant
  • office space and restaurants 20 cfm per occupant
  • hospitals 25 cfm per occupant

Related Topics

  • Physiology - Human physiology, air quality and comfort temperatures, activity and metabolic rates, health effects of carbon monoxide and more

Related Documents

Key Words

  • en: CO2 comfort levels parts per million ppm
  • es: Niveles de confort CO2 partes por mill√≥n ppm
  • de: CO2 Komfortstufen ppm parts per million

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