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CARBON DIOXIDE EXPOSURE EFFECTS – FACT SHEET
Studies by NIOSH in 1976 dispelled the myth that carbon dioxide is an asphyxiant gas and only causes
adverse health effects when it displaces oxygen.
Symptoms of overexposure by inhalation include dizziness, headache, nausea, rapid breathing, shortness of
breath, deeper breathing, increased heart rate (tachycardia), eye and extremity twitching, cardiac
arrhythmia, memory disturbances, lack of concentration, visual and hearing disturbances (including
photophobia, blurred vision, transient blindness, hearing loss and ringing in the ears), sweating, restlessness,
vomiting, shaking, confusion, flushed skin, panic, parathesis (a sensation of numbness in the extremities),
disorientation, convulsions, unconsciousness, coma, and death.
CO2
Concentration
Duration Physiological Impact/Health Effect
1,000 ppm Less than
2½ hrs.
Impairs judgment, decision-making ability, and thinking skills on a
short-term basis, even for healthy individuals.
2,500 ppm Less than
2½ hrs.
Many individuals are rendered cognitively marginal or
dysfunctional.
5,000 ppm with
20.9% Oxygen
Headache, lethargy, mental slowness, emotional irritation, and
sleep disruption.
6% 1-2 mins. Hearing and visual disturbances
7% (70,000 ppm)
with 20.9%
Oxygen
5 mins. death
10% to 15% Dizziness, drowsiness, severe muscle twitching, unconsciousness and
death within a few minutes.
17% to 30%
Within 1
min.
Loss of controlled and purposeful activity, unconsciousness, coma,
convulsions, and death
30% carbon
dioxide, with 70%
oxygen
30 secs. Unconsciousness, with some subjects having seizures that were
characterized as decerebrate (no cerebral functioning).
Even though oxygen is necessary to carry out cell functions, it is not the lack of oxygen that stimulates
breathing. Breathing is stimulated by an excess of CO2. If an individual breathes too slowly (bradypnea),
does not breathe deeply enough, (dyspnea), or is exposed to excessive CO2 levels, too much CO2 can build
up. This causes increased breathing and the other physiological responses discussed above.
Concentrated CO2 conditions impact most living organisms. Plant roots can actually be suffocated, which stops
the uptake of nutrients and kills the plants.
