What are the main health hazards associated with breathing in carbon dioxide gas?
Carbon dioxide (CO2) is naturally present in the atmosphere at levels of approximately 0.035%. Short-term exposure to CO2 at levels below 2% (20,000 parts per million or ppm) has not been reported to cause harmful effects. Higher concentrations can affect respiratory function and cause excitation followed by depression of the central nervous system. High concentrations of CO2 can displace oxygen in the air, resulting in lower oxygen concentrations for breathing. Therefore, effects of oxygen deficiency may be combined with effects of CO2 toxicity. Volunteers exposed to 3.3% or 5.4% CO2 for 15 minutes experienced increased depth of breathing. At 7.5%, a feeling of an inability to breathe (dyspnea), increased pulse rate, headache, dizziness, sweating, restlessness, disorientation, and visual distortion developed. Twenty-minute exposures to 6.5 or 7.5% decreased mental performance. Irritability and discomfort were reported with exposure to 6.5% for approximately 70 minutes. Exposure to 6%
