Tolerance Limits:Oxygen & Blood carbon dioxide concentration

• Human tolerance limit for blood CO2 concentration is 5 - 6%
• CO2 is not toxic at normal levels and is necessary to stimulate and control the rate and depth of breathing
• If the levels rise it can cause the pH to drop resulting in acidosis
• If the levels drop it can cause the pH to increase resulting in alkalosis
• Carbon dioxide is required to stimulate and control the rate and depth of breathing