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Is CO Heavier Than Air?

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Is Co Heavier Than Air Infographic. Carbon monoxide safety. Never ignore an alarm.Install CO detectors to protect your family

The majority of the air we breathe consists of 78 percent nitrogen, 21 percent oxygen, 0.93 percent argon, and 0.04 percent carbon dioxide. Among the gases in the air we normally breathe, carbon monoxide is becoming more prevalent due to its relationship with modern-day appliances. This causes many to wonder how carbon monoxide interacts with the air we breath and is CO heavier than air?

Carbon monoxide has a molecular weight which is slightly lighter than air; but despite that fact, it doesn't just rise to the ceiling. The difference in density between air and CO is minimal and because of this difference, it causes the gas to have a neutral effect in any room.

Unlike smoke, which rises, CO diffuses itself around the room and mixes with the air. We are not meant to breathe CO. If we do breathe CO, it can quickly affect our health. Since it mixes so well with the air, carbon monoxide is extremely dangerous and this adds to the necessity of making sure your home is protected from such a deadly gas.

Danger sign with skull and crossbones on a green metal wall.

Why is Carbon Monoxide Dangerous?

Carbon monoxide (CO) is a clear, odorless, and tasteless gas that can kill you. It is created and found in fumes associated with burning fuel found in cars, trucks, buses, engines, and other modes of transportation. It is also found in home appliances like stoves, grills, lanterns, fireplaces, and even furnaces.

Because CO is produced by so many appliances and utilities that are used on a daily basis, it is important to be informed and cautious. If CO builds up indoors, it can poison both people and animals who breathe it.

Carbon monoxide replaces the oxygen in your red blood cells when you breathe it in. This forms a compound in the body called carboxyhemoglobin which is dangerous. When this biological compound forms in the body’s bloodstream, it can lead to serious tissue damage throughout the body.

Often, damage may be irreparable, and can even lead to death. Brain damage can also result from CO poisoning and besides being irreparable, it can have devastating effects on developing children.

Unfortunately, it is not easy to know if you have been exposed to CO. The symptoms are often described as flu-like, which include symptoms such as chest pain, nausea, confusion, dizziness, weakness, and an upset stomach. Breathing in a significant amount of CO can cause you to pass out and can kill you. People who are drunk or sleeping can die from CO poisoning before they experience any symptoms.

Man in a gray shirt with hands over his eyes as if in pain.

The CDC has classified carbon monoxide as immediately dangerous to life. They report that spending just one hour in your home, apartment, or office, where a carbon monoxide concentration is between 1500 to 2000 PPM, can be lethal.

PPM (Parts Per Million) references the concentration of a particle in either air or water. This concentration means that if 0.15-0.20 percent of the air quality consists of CO, it begins to be lethal. Higher concentrations are considered even more dangerous and can produce negative health effects and cause death faster.

Anyone who believes they may have been exposed to dangerous amounts of CO should go to the hospital or a doctor immediately. Because of the dangers associated with CO and the permanent effects it can create, it is always better to err on the side of caution.

Those who have experienced prolonged exposure need to use hyperbaric oxygen therapy to reverse the harmful effects of existing carboxyhemoglobin which had developed in their body. This is not an easy treatment and is an expensive therapy required for a condition that can be prevented from occurring. Keeping yourself and loved ones from experiencing carbon monoxide poisoning will prevent need for this type of therapy.

Skull and crossbones sign inside of a triangle on a yellow sign.

How Heavy Is Air?

Air weighs 14.7 pounds per square inch (at sea level), meaning every square inch of your body is getting pushed on by 14.7 pounds of pressure. Sounds like a lot, doesn't it? Makes you wonder how we can all stand upright and stay alive with that amount of force constantly pressing on us. Thankfully, our bodies counteract that pressure but applying its own pressure outward as we breathe in and out.

When talking about air, weight/heaviness also means "pressure." So when you see the barometric pressure, it means the atmospheric pressure, or weight of the air.

As you can imagine, the weight/pressure in any given area of the world will be different depending on a lot of factors, such as sea level, temperature, etc. You can check your area's current barometric pressure on a weather app. It can change throughout the day and from day to day. Altitude can also affect it. At higher altitudes, the air pressure is typically lower than at sea level.

Measuring Air’s Density

Density of something is how tightly spaced or loosely spaced the molecules are. A metal cube, for example, is much more dense than a marshmellow. When it comes to gases, they have less density than solids or liquids. Even comparing different gasses, they all have different denisties.

Remember that air is made up of several different gases, so the densities of each of those will affect the current total air density. At a constant temperature, pressure and volume, dry air is typically made of 78% nitrogen, 21% oxygen, and one percent argon.

The formula to measure density is density = mass/volume. Air density at sea level is, on average, around 1.225 kg/m3. That will go up or down depending on what all is in the air. If it is humid, for example, the H20 molecules are denser, which will cause the total air density to be slightly higher.

Air pressure/weight and air density are related. Typically when one goes up or down, the other does as well. That's because pressure is a result of gravity, and density is a measure of how close together molecules are. Like air pressure, at higher altitudes, the density is lower than at sea level.

What Types of Gases are Heavier Than Air?

It's important to know what types of gases are heavier than air so you know how they will act. For gasses that are heavier than air, like those listed below, when they are released into the air they sink. In the case of flammable gases, be extremely cautious. Gases heavier than air don't tend to vent safely. Be sure to note the toxic gases.


Butane is a flammable gas used in cigarette lighters and portable stoves, among other things. Weighing in at 2.5436 kg/m³ butane has a little over two times the weight of air. Butane has a low toxicity, so butane poisoning isn't usually a worry unless breathed in high amounts.


Propane is an ingredient in "natural gas." (Compressed natural gas has methane, nitrogen, CO2, propane, and ethane.) Propane is a flammable gas that is used for heating your home, heating your water, cooking food, drying clothes, and more. Propane weighs in at 1.898 kg/m³ so it's 1.55 times the weight of air.

While the vapor that comes off of propane isn't toxic, it is an "asphyxiating" gas, meaning it can displace the oxygen in your lungs, making it hard to breathe and even causing death. Since propane puts off carbon monoxide (CO), it is vital that you have a CO detector in your home to detect leaks right when they start.

Carbon Dioxide

Carbon dioxide (CO2) is an ingredient in "natural gas." (Compressed natural gas has methane, nitrogen, CO2, propane, and ethane.) Carbon dioxide is used in fire extinguishers, in carbonated drinks, and many other things. Carbon dioxide weighs 1.87 kg/m3, so it is 1.5 times the weight of air.

Sulfur Dioxide

Sulfur dioxide is not flammable. It is used for manufacturing food preservatives and paper, among other things. Sulfur dioxide has a weight of 2.927 kg/m3 so it is more than twice the weight of air. Sulfer dioxide is highly toxic and smells like eggs.

What Types of Gases are Lighter Than Air?

Just as it's important to know what types of gases are heavier than air, you should also know which gases are lighter than air. These are gases that vent more easily than heavier gases, since they rise above and dissapate into the air, making it less likely for people to breathe. Still, be extra cautious esepcially with flammable and toxic gases.

Carbon Monoxide

Carbon monoxide (CO) is flammable and poisonous. It is used as a source of energy and a reducing agent, meaning it helps convert metal oxide into pure metal. Carbon monoxide weighs 1.14 kg/m³ so it is slightly less than air and it will dissapate evenly in an upward motion.


Ammonia gas is flammable and corrosive, and in high doses can result in damage to a person's brain, lungs, or even death. It is mostly used as farming fertilizer, among other things. Ammonia weighs 0.73 kg/m³, so it's less than air.

Natural Gas

Compressed natural gas has methane, nitrogen, CO2, propane, and ethane. Natural gas can be flammable and toxic, depending on the dose. Natural gas weighs 0.68 kg/Sm3, so much less than air.


Methan is flammable but is not generally toxic, though in cases of high doses can cause suffocation. It is mostly used as fuel to make heat and light. Methan weighs 0.657 kg/m³, so much less than air.


Helium, as most people know, is used for party balloons. But it's also used research, the medical and manufacturing industries, among others. Helium only weighs 0.166 kg/m 3, which is why it rises in air so easily. It is nontoxic unless consumed in large amounts. It is not flammable.

What is the Difference Between Carbon Monoxide (CO) and Carbon Dioxide (CO2)?

Carbon monoxide and carbon dioxide are often confused, and although both can be dangerous and deadly, it is important to know the distinction.

Carbon dioxide is produced when energy is released from burning fossil fuels, natural gas, and oil. As well, carbon dioxide is emitted as part of both plant and human respiration. Once carbon dioxide is released it quickly mixes into the atmosphere. Despite humanity’s hand in creating more CO2, this is a naturally occurring gas and is part of the environment.

Carbon monoxide is created from incomplete combustion which is a result of limited air supply. When only half as much oxygen is added to carbon, CO is formed. Fuel-burning appliances, including gas furnaces, gas stoves, gas dryers, gas water heaters, fireplaces, and cars are all industrial activities which create CO.

Although both CO and CO2 are dangerous and known to be toxic gases, CO is by far the more deadly. It is known as the silent killer and the CDC reported that yearly 50,000 people are hospitalized for poisoning and 430 people died as a result.

Neither gas is detectable without using a gas detector. Along with using detectors, there are several other things that should be done and avoided to protect your home.

Pipes pumping out Carbon Monoxide in a warehouse of metal and cement

How Can You Protect Your Home?

The first step in protecting your home and family from carbon monoxide is determining the current levels of CO in your home. Maintaing good indoor air quality keeps you and your family healthy and should take priority. Identifying existing sources and potential issues will help you to know where action should be taken.

By checking and identifying the potential sources, such as gas appliances, you can see what improvements can be made and where you are most at risk. Using tools to measure levels of carbon monoxide in enclosed spaces can make sure that CO does not build to unsafe levels in your home.

Knowing where you are at risk and what appliances may expose you to CO in your home will help you know what to monitor to ensure everything is in good repair. You can’t fix something that you don’t know is broken. Poorly constructed or broken exhaust vents can leak carbon monoxide into your home and if not properly repaired, it can be a continuous danger to you and your family.

To ensure that CO producing appliances are in good repair, hire a professional technician to service them each year. Having someone with the proper tools, training, and knowledge check your appliances will help mitigate accidental damages and issues. Poorly repairing or damaging something that emits a deadly gas increases your risk of exposure. All ventilation around your gas appliances, including stoves, water heaters, etc. should be checked and the pipes should be positioned horizontally as they move outdoors.

Cleaning out vents and pipes, chimneys and fireplaces, and woodburning stoves or heaters helps to prevent CO from building up in your home. Cleaning and inspecting fireplace flues makes sure that smoke and CO are properly filtered out of the home rather than accidentally into it.

Along with following the above recommendations, protect your home from the dangers of carbon monoxide and prevent carbon monoxide poisoning by installing CO detectors in your home. A good CO detector will alert you to the presence of CO and can even notify the fire department so that they may respond. A quick response can help repair the cause of exposure so you can safely remain in your home. Install CO detectors within five feet of every gas appliance, in every sleeping area, and on every level of the home.

Charcoal being burned inside of a house giving off carbon monoxide.

Carbon Monoxide Safety Don’ts

Part of using good safety practices is knowing what should not be done. There are a few things which can increase your chances of exposure, all of which are easily avoidable.

You should never burn charcoal inside your home. Red, gray, black, and white charcoal all give off carbon monoxide and homes are not ventilated for this kind of exposure (even with the windows open.) Along with burning charcoal, you shouldn’t use outdoor or portable gas stoves inside.

All appliances such as an oven, gas range, or stove can all emit carbon monoxide and should never be used for heating your home. Chemical heaters should also be used only outside and away from any doors or windows where fumes could filter inside.

Protect Your Family with CO Detectors and Monitoring

By installing carbon monoxide detectors in your home, you will be able to alert yourself and your family in case of an emergency. Cove provides affordable options to make sure that your home is safe. To learn more about CO detectors and how they will help you protect your home, click this link.

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