Both carbon monoxide (CO) and carbon dioxide (CO2) are both colorless, odorless gases that are combinations of carbon and oxygen, which is why they have similar names, but they are created through different chemical reactions.
Carbon monoxide is one part carbon and one part oxygen, and carbon dioxide is one part carbon and two parts oxygen.
Carbon monoxide is created through an incomplete combustion of coal, natural gas, and oil. CO may occur through natural events such as forest fires or volcanic activity, but it can also be produced artificially by fuel-burning appliances such as motor vehicles, gas-powered generators, and propane stoves.
CO poisoning is much more common and dangerous than CO2 poisoning because the CO binds to the parts of the blood that carry oxygen molecules, and chemically blocks the body and organs from getting the oxygen it needs. Carbon monoxide poisoning is often called “the silent killer” because it is odorless, colorless, tasteless, and non-irritating so early signs of poisoning are harder to detect.
Carbon dioxide occurs naturally in the atmosphere as a byproduct of human and animal respiration, fermentation, combustion of wood or fossil fuels, and other sources, though it can be toxic in highly concentrated amounts. Excess CO2 takes up space in the air instead of oxygen, which creates an environment in which a person can suffocate (asphyxiate) and causes a condition called hypercapnia (or hypercarbia). CO2 poisoning is rare.
What Are Symptoms of Carbon Monoxide and Carbon Dioxide Poisoning?
Symptoms of carbon monoxide (CO) poisoning include:
- Headache
- Dizziness
- Weakness
- Tiredness
- Upset stomach
- Vomiting
- Chest pain
- Confusion
- “Flu-like” symptoms without fever
- Fainting
- Seizures
- Death
Symptoms of carbon dioxide (CO2) poisoning include:
- Headache
- Dizziness
- Nausea
- Vomiting
- Rapid breathing and heart rate
- Flushing
- Confusion, convulsions, and loss of consciousness (in severe cases)
What Causes Carbon Monoxide and Carbon Dioxide Poisoning?
Carbon monoxide (CO) is produced by fumes from burning fuel in motor vehicles, small engines, stoves, grills, gas ranges, lanterns, fireplaces, or furnaces. When there is inadequate ventilation or faulty equipment CO can build up indoors and poison people and animals who breathe it.
There are a number of causes of carbon dioxide (CO2) poisoning, including conditions that affect gas exchange in the body, such as:
- Chronic obstructive pulmonary disease (COPD)
- Sedative overdose (e.g., narcotics or benzodiazepines)
- Encephalitis
- Major stroke
- Central and obstructive sleep apnea
- Primary and central alveolar hypoventilation syndromes
- Brainstem disease
- Metabolic alkalosis
- Hypothyroidism
- Hypothermia
- Smoking or sedentary lifestyle
- Overweight/obesity
- Cervical spine injury (above C3) with diaphragmatic paresis/paralysis
- Amyotrophic lateral sclerosis (ALS)
- Poliomyelitis
- Guillain-barré syndrome
- Phrenic nerve injury or neuropathy
- Myopathy due to hypo- and hyperthyroidism
- Myasthenia gravis
- Critical illness polymyoneuropathy
- Muscular dystrophy
- Polymyositis
CO2 poisoning also can occur in divers, particularly if they dive quickly and deeply, forget to breathe, hyperventilate, or have malfunctioning equipment.
How Is Carbon Monoxide and Carbon Dioxide Poisoning Diagnosed?
In addition to a patient history and physical examination, bit carbon monoxide and carbon dioxide poisoning are diagnosed with a blood test.
The severity of CO poisoning may be confirmed by measuring a patient’s carboxyhemoglobin (COHgb) level either in whole blood or with a blood gas test.
What Is the Treatment for Carbon Monoxide and Carbon Dioxide Poisoning?
Carbon monoxide (CO) poisoning is treated in the hospital with oxygen, usually administered for 4 to 5 hours. Hyperbaric oxygen therapy (HBO) may be used in some cases when CO poisoning is more severe, the patient has other underlying medical conditions, or is pregnant (even if the CO poisoning is less severe).
Carbon dioxide (CO2) poisoning can sometimes be treated just by having patients breathe in normal air. In more severe cases, oxygen may need to be administered and hyperbaric oxygen therapy may be used.
How Do You Prevent Carbon Monoxide and Carbon Dioxide Poisoning?
To reduce the chances of carbon monoxide (CO) poisoning:
- Install a CO detector in your home
- Have one on each floor
- If it is battery-operated, make sure to change the batteries every 6 months
- Ensure all fuel-burning appliances (such as gas water heaters, gas stoves, gas clothes dryers) in the home are working correctly
- Make sure all vents in the heating system are working correctly
- Have fireplaces and wood-burning stoves checked professionally as recommended by the manufacturer, and make sure the flue is open when in use
- Never leave a motor vehicle running in a garage, even if the garage door is open
- Only operate a generator outside, at least 20 feet from the house
- Never run a generator inside the home or garage or just outside a window, door, or vent that goes into the house
- Never use a charcoal grill or portable propane grill indoors, or in poorly ventilated spaces such as garages, campers, or tents
From 
Healthy Resources
https://www.cdc.gov/co/faqs.htm
https://www.cdc.gov/disasters/co_guidance.html
https://www.uptodate.com/contents/carbon-monoxide-co-poisoning-the-basics?search=Carbon%20Monoxide%20poisoning&source=search_result&selectedTitle=1~89&usage_type=default&display_rank=1
https://www.uptodate.com/contents/mechanisms-causes-and-effects-of-hypercapnia?search=Mechanisms,%20causes,%20and%20effects%20of%20hypercapnia&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
https://www.healthychildren.org/English/safety-prevention/all-around/Pages/How-to-Prevent-Carbon-Monoxide-Poisoning.aspx