CO toxicity mimics a wide range of conditions: the symptoms of acute exposure are well-known, and include headache, nausea and drowsiness.
Chronic exposure to low levels also damages the heart, brain and other tissues. Its effects can be even more wide-ranging, and include -
fatigue
low or unstable mood
cognitive decline
loss of vision
loss of hearing
other neurological disorders, such as tremor
impaired cardiac performance
Children and the unborn are especially vulnerable to CO poisoning, which can also lead to -
stillbirth
low birth weight
developmental delay
behavioural disorders