Table 3.

Detailing the effects of concentration and exposure time of CO₂ on human health Taken from occupational health and safety website in Canada [54].

CO2 Concentration and Exposure time	Effect on Health (symptoms)
0.035%	Approximate atmospheric concentration, no noticeable effect.
3.3–5.4% for 15 mins	Increased depth of breathing
7.5% for 15 mins	Feeling of an inability to breathe, increased pulse rate, headache, dizziness, sweating, restlessness, disorientation, and visual distortion.
3%, for over 15 hours	Decreased night vision, colour sensitivity
10%, 1.5 mins	Eye flickering, increased muscle activity, twitching
10+%	Difficulty in breathing, impaired hearing, nausea, vomiting, a strangling sensation, sweating, after 15 minutes a loss of consciousness.
30%	Unconsciousness, convulsions. Several deaths attributed to CO2 at concentrations of more than 20%