Carbon monoxide poisoning symptoms

Carbon monoxide poisoning symptoms

Carbon monoxide poisoning symptoms: Carbon monoxide, whose chemical formula is CO, is an odourless, colourless, flammable (LEL-12%, UEL- 75%, NFPA flammability – 4) and highly toxic gas (NFPA health hazards – 3. It is a very toxic gas for people and animals. It enters the body through the lungs and from there it passes into the blood, taking the place of oxygen. It reduces the oxygen-carrying capacity of the blood and makes cells unable to use the oxygen that reaches them.

Lack of oxygen mainly affects the brain and heart. It can cause serious poisoning, even death. It is called the silent killer because:

  • It does not smell
  • It does not have colour
  • It does not have a flavour
  • Does not irritate the eyes or nose

Carbon monoxide poisoning symptoms are more frequent in cold times because the use of all types of heaters increases and because doors and windows are often closed, preventing the entry of fresh air, and also the exit of toxic gases that accumulate the inside the houses. Any appliance that uses combustible material (gas, oil, coal, kerosene, naphtha, wood, plastics) can produce carbon monoxide when burned incompletely:

  • Heaters, hot water tanks, boilers
  • Kitchens stoves, heaters, wood or charcoal grills, gas or wood ovens
  • Combustion engines (vehicles, chainsaws, electric generators, etc.).

Carbon monoxide (CO) is generated during the incomplete combustion of natural gas (also butane or propane cylinders) in defective burners (mainly in boilers or gas heaters) or in poorly ventilated spaces. It is also a product of the combustion of coal, coke or kerosene in furnaces (and wood in chimneys) with faulty flues. It is also found in smoke from fires (along with other gases: cyanides, sulfur oxides and nitrogen oxides).

Carbon monoxide poisoning symptoms
Carbon monoxide poisoning symptoms

When you breathe it in, it causes a change in the blood cells that prevents them from carrying oxygen. The lethal dose depends on the concentration of CO in the inspired air, duration of exposure, and respiratory activity (amount of toxin received). A concentration of 1000 ppm (0.1%) is life-threatening. A concentration of 1500 ppm (0.15%) is fatal in a short space of time.

Each year, more than 400 Americans die from carbon monoxide poisoning not associated with fire, more than 20,000 people visit emergency rooms, and more than 4,000 are hospitalized. Unless suspected, CO poisoning can be difficult to diagnose because the symptoms are similar to other medical conditions like the flu.

What are the carbon monoxide poisoning symptoms?

CO poisoning can occur any time someone is exposed to a toxic level of carbon monoxide. Due to the use of gas-fired heating appliances and generators, more carbon monoxide poisonings occur during the winter than during the rest of the year.

If several people in the household have Carbon monoxide poisoning symptoms at the same time, consider CO poisoning. Children, the elderly, and those with medical conditions are usually affected first.

For most people, the first Carbon monoxide poisoning symptoms of low concentrations of CO include mild headaches and shortness of breath with moderate exercise. Continued exposure may cause flu symptoms, including increased headaches, dizziness, tiredness, nausea, confusion, irritability and fuzzy thinking, and poor memory and coordination.

CO is called “the silent killer” because if one does not pay attention to these early signs, the person may lose consciousness and the ability to get out of danger.

The person may have no Carbon monoxide poisoning symptoms and still be exposed to dangerous levels of CO. Breathing low concentrations of CO may not result in obvious symptoms of CO poisoning, but this low exposure can still cause long-term health damage, even after the CO source has been removed.

These effects include long-term neurological damage, such as difficulty learning and retaining memory, emotional and personality effects, and sensory disturbances. the Carbon monoxide poisoning symptoms are:

  • Headache
  • Confusion
  • Weakness
  • Dizziness or Fainting
  • Nausea and vomiting
  • Drowsiness
  • Fatigue
  • Loss of consciousness and/or seizures
  • palpitations
  • Chest pain
  • Cardiorespiratory arrest
  • High CO levels can cause death

Effects of carbon monoxide on human health

Headache (more frequently) and dizziness, nausea, vomiting, balance and orientation disorders, weakness, fatigue, tachycardia, arrhythmias, drop in blood pressure, consciousness disorders (including coma), seizures; symptoms of myocardial ischemia (even in people without the coronary disease); Generally pale and cyanotic skin (a deep red colour is observed only after death or in the most severe poisoning).

Carbon monoxide poisoning symptoms
Carbon monoxide poisoning symptoms

Extremely high exposure to carbon monoxide can cause the formation of carboxyhemoglobin, which reduces the blood’s ability to carry oxygen and can cause a bright red colour to the skin and mucous membranes, respiratory distress, collapse, seizures, coma, and death.

Smoking increases your exposure to carbon monoxide, as it can cause heart disease, as well as lung cancer, emphysema, and other respiratory problems, and can aggravate respiratory conditions caused by chemical exposure. Even if you have been smoking for a long time if you quit today your risk of health problems will be reduced.

Causes damage to the blood if inhaled. Causes damage to the blood and the central nervous system through prolonged or repeated exposure if inhaled.

Effects of short-term exposure

The substance may affect the blood. This can lead to carboxyhaemoglobinemia and cardiac disturbances. Exposure to high concentrations could cause death. Medical surveillance is recommended.

Effects of prolonged or repeated exposure

The substance may have effects on the cardiovascular system and the central nervous system. It can cause alterations in human development or reproduction.

Carbon monoxide exposure


30ppmDaily exposure at this concentration is equivalent to smoking 20 cigarettes a day.
35ppmPeople who have heart disease should not be exposed to levels above this concentration.
200-400ppmAfter 5-6 hours you can see a slight headache, nausea, dizziness and mental symptoms
400-700 ppmAfter 4-5 hours a severe headache, muscle incoordination, weakness, vomiting and collapse can be observed.
700-1100 ppmAfter 3-5 hours a severe headache, weakness, vomiting and collapse can be observed
1100-1600 ppmAfter 1.5-3 hours coma can be observed. (breathing is still pretty good unless the poisoning has been prolonged)
1600-2000 ppmAfter 1-1.5 hours there is a possibility of death
5000-10000 ppmDeath can occur after 2-15 minutes

Preventive measures for carbon monoxide poisoning

There are several steps you should take to prevent carbon monoxide poisoning. Use the following checklist to ensure that you are doing everything possible to prevent Carbon monoxide poisoning symptoms.

Carbon monoxide poisoning symptoms
Carbon monoxide poisoning symptoms
  • Check your heating, boiler, and any other gas, oil, or open flame device every year.
  • Make sure your gas appliances have adequate ventilation
  • Check/clean chimneys every year. Chimneys clogged with debris can cause carbon monoxide buildup in your home.
  • Never use charcoal grills inside the home. Coal produces CO when it is lit/used.
  • Never use a generator inside the home or garage, even if you have the door or windows open.
  • If you use a generator outside the home, make sure it is more than 15 feet away from any door or window.
  • Never keep your car running inside the garage attached to the home, even if the door is open.
  • Always open a garage door away from home if you have your car running.

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Carbon monoxide exposure limits chart


: TWA of 35 ppm (40 mg/m 3) C of 200 ppm (229 mg/m 3)


: 50 ppm TWA (55 mg/m 3)

CO exposure limit

STANDARDTWA (8 Hours)STEL (15 Minutes)IDLH
NIOSH (REL)35 PPM200 PPM1200 ppm

Prevent unsafe exposure to CO in the workplace

The permissible exposure limit prohibits worker exposure to more than 50 parts per million parts of air averaged over 8 hours. Exposure to concentrations greater than 100 parts per million is a serious violation, and any exposure greater than 500 parts per million is considered an imminent danger.

Carbon monoxide poisoning symptoms
Carbon monoxide poisoning symptoms

The National Institute for Occupational Safety and Health has recommended that the standard be changed to less than 40 parts per million and that any exposure beyond 200 parts per million is strictly prohibited. To reduce the chances of CO poisoning in the workplace, it is recommended to take the following precautionary measures:

  • Maintain equipment and appliances (e.g. water heaters, space heaters, stoves) well to reduce CO formation.
  • Consider switching from gasoline-powered equipment to equipment that runs on electricity, batteries, or compressed air.
  • Install CO monitors with audible alarms. Provides personal CO monitors with audible alarms if possible CO exposure exists.
  • Test the air regularly in areas where CO may be present, especially in confined spaces.
  • Use a certified full-facepiece pressure-demand self-contained breathing apparatus, or a combination full-facepiece pressure-demand supplied-air respirator with an auxiliary self-contained auxiliary air supply in areas with high CO concentrations.
  • Use respirators with appropriate canisters for short periods under certain circumstances where CO levels are not excessively high.
  • Educates workers about the sources and conditions that can lead to CO poisoning, as well as the symptoms and control of CO exposure.
  • Make sure workers test for oxygen sufficiency before entering confined spaces.

Carbon monoxide safety data sheet

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