Do Air Conditioners Create Carbon Monoxide Or Carbon Dioxide? 

Air conditioners are used in almost 90% of American households and are a prime contributor to global warming. The use of refrigerants, chimney effect, and high energy consumption produce significant amounts of greenhouse gases by AC units. However, does the greenhouse effect involve CO₂ or CO emission?  

Air conditioners are electrical appliances. Since their working mechanism does not involve combustion, they do not create CO₂ and CO. However, AC units have a significant carbon footprint due to high energy consumption.  

In this article, we dig into the working mechanism of air conditioners and how it relates to the production of carbon dioxide and carbon monoxide. We talk about the harmful implications of the two gases on health and the environment, explaining why it is crucial to reduce the carbon footprint of air conditioners.  

Carbon Dioxide 

Constituting 0.04% of air, carbon dioxide or CO₂ is a colorless gas with an acidic odor. It is primarily produced as a product of combustion (a process in which fuel like natural gas, coal, etc., reacts with oxygen to give off energy).  

When carbon from fossil fuel combines with oxygen, it creates CO₂ as a by-product. 

While cigarette smoke, fire, decomposition of materials, natural decay, and weathering of rocks are the primary sources of CO₂, the gas is also emitted from many energy-consuming domestic appliances. On average, US households produce 7.5 tons of CO₂ annually.  

Today, CO₂ is an integral part of the food, oil, and chemical industries and is commercially produced on a large scale.  

Toxicity 

High CO₂ concentration in the air naturally implies inhalation of more than average levels of CO₂. Since lungs have a specific capacity, i.e., 6 L of air, high CO₂ results in low oxygen levels in the body.  

Oxygen is essential for energy synthesis and ultimately carries out vital functions. Upon oxygen deprivation, the body is left with inadequate energy, which leads to impairment and eventual dysfunction of the nervous system, heart, and other organs.  

Side Effects 

The common side effects of CO₂ toxicity are as follows: 

• Headache  
• Chest pain 
• Shortness of breath and hyperventilation 
• Flushing (redness of the skin) 
• Disorientation  

More than 40,000 ppm of CO₂ results in instant death.  

Carbon Monoxide 

Carbon monoxide or CO is a colorless and odorless gas, commonly known as a silent killer. Almost 100 ppb (0.1 ppm) of CO naturally exists in Earth’s atmosphere. 

It is produced from incomplete thermal combustion. Exhaust fumes from vehicles, fireplaces, construction materials, and heating appliances (like furnaces) are a common source of CO exposure in homes. 

Toxicity 

Oxygen binds to a red blood cell protein called hemoglobin (Hb) for transportation across the body. However, Hb has a 250 times higher affinity for CO than oxygen; therefore, upon inhalation, CO quickly displaces oxygen in the body.  

The low oxygen levels immediately end in severe energy deprivation, damaging our vital organs. 

Side Effects 

Here are the common side effects of CO: 

• Nausea 
• Fatigue  
• Disorientation  
• Miscarriage  
• Anorexic brain injury (due to severed oxygen supply) 
• Ischemia (reduced blood flow to the heart) and eventual heart failure 
• Memory loss 
• Difficulty concentrating  
• Hallucinations  

These symptoms (also known as CO poisoning) start showing at the exposure of 70 ppm or more of CO. Whereas beyond 150 to 200 ppm of the gas can lead to death.  

How Do Air Conditioners Work? 

To understand the by-products emitted through the air conditioning process, it is crucial to understand how ACs work. 

Air conditioners typically consist of two fans, an evaporator coil, refrigerant, compressor, and vent.  

The first fan rotates to draw warm air inside the unit via return air ducts. If the system has a pre-installed filter, the airborne contaminants are removed from the incoming air stream.  

The type of pollutants extracted depends on the type of filter. While a generic filter is only able to catch dust and large particles, a True HEPA filter can capture microscopic infiltrates, even pathogens. Electrostatic fiberglass and pleated media filters also remove sediments and particulate matter. In contrast, the activated charcoal filters prevent the gases and VOCs from going forward with the air stream. 

The filtered air encounters a cold evaporator coil with a refrigerant sealed inside. Heat and humidity is tranferred from the air to the refrigerant, and as a result, the air temperature drops. A blowing fan then propels cold air out of the AC. 

On the other hand, the now gaseous refrigerant passes into the compressor. Here, pressure is applied to the chemical, forcing it to expel heat outside through the vent. The refrigerant then returns to the evaporator coil to continue the cycle. 

A thermostat regulates this entire process. It monitors room temperature and temporarily stops the cycle once the preset temperature is attained.  

Do Air Conditioners Create Carbon Monoxide and Carbon Dioxide?

We know that CO is created from incomplete combustion. Carbon is not completely oxidized when oxygen is in deficit, resulting in CO production.  

Similarly, CO₂ is a product of combustion.  

Appliances that emit CO₂ actively employ heating processes. For example, furnaces burn fuel to heat air and blow it through ducts.  

These heating units also create CO in case of internal faults. For example, a dirty furnace filter blocks the airflow, decreasing the incoming oxygen. Inadequate oxygen levels lead to the creation of CO in the heating chamber. Obstruction in any part of the furnace, oversizing ducts, etc., can have the same effect.   

However, since air conditioning is electrical and does not directly involve burning fuels in the home, AC units do not emit CO₂ and CO (in case of low oxygen supply). 

However, in hindsight, air conditioners are responsible for more than 10% of global CO₂ emissions. They have high energy consumption, implying that tons of fossil fuels are burned to run a single AC unit.  

Data suggests that air conditioners use about 6% of electricity produced in the USA. As a result, 117 million metric tons of CO₂ are released into the air annually.   

Can Air Conditioners Draw Carbon Dioxide and Carbon Monoxide From Outside? 

Air conditioners are not supplied with fresh air; instead, they recirculate the indoor air for each air conditioning cycle. Therefore, they do not draw CO₂ or CO from outside. 

However, running an AC for a long time can indirectly lead to a rise in CO₂ concentration in the room. Closing all the windows and doors shut is essential to ensure maximum cooling efficiency from air conditioners.  

Due to the consequent poor ventilation, the CO₂ that we naturally exhale keeps building up in the room. This is associated with ‘sick building syndrome. 

Sick building syndrome or SBS is a set of acute health effects, you experience after being confined in close spaces for long hours. The common signs include: 

• Headache 
• Dizziness  
• Fatigue  
• Difficulty concentrating 
• Hoarseness of voice 
• Allergies  
• Increase in asthma attacks 

Do Air Conditioners Produce Any Toxic By-Products? 

While air conditioners do not create CO₂ and CO, they produce greenhouse gases. This is because they use refrigerants like Freon, HCFC, and HFC that have high GWP (global warming potential).  

While refrigerant is sealed inside the evaporator coil, some of it can leak outside the system. Other than increasing the planet’s temperature to a dangerous level, these chlorine-containing chemicals also play a massive role in ozone depletion. 

The chimney effect, whereby AC units keep releasing heat outside the house, has a drastic impact on the environment. 

Can I Get Carbon Monoxide Poisoning From My Air Conditioner? 

Air conditioners do not produce carbon monoxide, even when faulty. Therefore, AC units are not a potential source of CO poisoning.  

How Do You Know If Your Air Conditioner Is Leaking Carbon Monoxide? 

Air conditioners do not create CO. However, the recycled air used in AC units may contain the gas. This is detectable by soot stains, a distinct smell of exhaust gases, as well as initial signs of CO poisoning (headache, shortness of breath, wheezing, and nausea). 

Furnaces, heaters, fireplaces, stoves, pressure cookers, etc., can all emit CO. Even if an air conditioner has an activated charcoal filter, CO molecules are likely to escape the comparatively larger filter pores; thus, if CO enters along with the original warm air stream, it is emitted out of the AC unit into the room. 

Here are three ways you can detect rising CO concentration in the room: 

i) CO Monitors  

Carbon monoxide monitors are devices that detect CO concentration in a room with the help of an electrically charged sensor. They are highly sensitive to even slight changes in CO levels and, therefore, ring an alarm when CO is too high.  

In case of 50 ppm or less concentration, the alarm takes a few hours to go off. However, if the exposure is to a higher level, you will be alerted within a few minutes.  

CO poisoning claims more than 400 American lives each year. Since it is a silent killer, it is essential to have a CO monitor installed at every home.  

If you consider buying a device, we recommend Google Nest Protect.

It is a smoke and CO detector that not only sets off an alarm to alert in case of a CO leak but also indicates the original source /area of the gas leak via the Split Spectrum Sensor. 

Additionally, for the user’s convenience, it also has a night light, battery indicator, and versatile controls. 

Moreover, it is compatible with Google, which enables you to control the device remotely through your smart devices.  

ii) Soot Stains 

Incomplete combustion results in the formation of yellow or back powder stains around the appliance. These are called soot stains. If anything in your room is producing CO, you will find stains around the area or on the nearby furniture.  

iii) Smell Of Exhaust Gases 

CO leak is accompanied by the emission of various exhaust gases (produced during combustion). Even though CO is odorless, the smell of other gases is pungent and distinct. 

iv) CO Poisoning 

The symptoms of CO poisoning are progressive. While severe respiratory distress, cognitive failure, and heart problems may have a late onset, the initial signs of wheezing, difficulty breathing, and general discomfort manifest as soon as you’re exposed to high levels of CO. 

If everyone around the house starts experiencing these symptoms simultaneously, you should suspect a possible CO leak.  

Can The Air Conditioning Set Off A Carbon Monoxide Monitor? 

Air conditioners cannot produce carbon monoxide and, therefore, do not set off a CO monitor.