Carbon Monoxide Alarm Closeup

“Incomplete combustion” is happening all across Canada and around the world in homes and workplaces every single day.

The world as we know it relies on combustion to keep going. In this post, learn what you need to know to make sure the combustion happening in your home or workspace is safe (complete) and non-toxic.

What Is Incomplete Combustion?

At its simplest, combustion is what happens when we burn a fuel.

Complete combustion is often called “clean combustion.” Incomplete combustion is often called “dirty combustion.”

To generate combustion, there must be a heat source, a fuel type and an oxidant (oxygen). When a heat source plus oxygen and fuel interact, the result is also heat, along with trace amounts of carbon dioxide and water.

Common fuel types include wax, wood, oil, gas, kerosene, propane and coal. Tobacco is another common fuel type.

Combustion is pretty great when we want to heat our homes or offices, cook something or drive our car.

But it isn’t so great when it doesn’t work properly and produces toxic airborne waste.

What Does Incomplete Combustion Produce?

Complete combustion fully oxidizes the fuel and produces the maximum possible amount of heat energy.

Incomplete combustion, on the other hand, produces both heat energy and other byproducts that are both unhealthy and unsafe.

Incomplete combustion happens for one of two reasons: there isn’t enough oxygen to fully oxidize the fuel or the initial heat source isn’t hot enough to fully consume the fuel.

When this occurs, both gaseous compounds and particulate matter are produced, which are unsafe and unhealthy. Some of them can be fatal.

Most Common Byproducts of Incomplete Combustion

These are the most concerning byproducts that are produced when combustion is not complete.

Carbon dioxide

Carbon dioxide, or CO2, is the least concerning of these byproducts. Carbon dioxide at high levels can cause fatigue, headaches, dizziness and similar health symptoms.

When air is described as “stale,” this often means there is a high ratio of carbon dioxide to oxygen present.

Carbon monoxide

CO, or carbon monoxide, is the most concerning of these byproducts. Nicknamed the “silent killer,” carbon monoxide is odourless and colourless – impossible to detect without a carbon monoxide alarm system.

At low levels, CO can cause fatigue, headaches, dizziness, nausea, mental confusion, vision problems and symptoms similar to the flu. At high levels, carbon monoxide can be fatal.

Nitrogen dioxide

Nitrogen dioxide, or NO2, is a byproduct that is particularly concerning if you have chronic respiratory or breathing issues, such as asthma. Symptoms include irritation and inflammation in the eyes, nose, throat and lungs, and shortness of breath.


Particulate matter (PM), or soot, is composed of small floating particles that readily enter your eyes, nose and mouth, causing irritation and inflammation down into the lungs and the heart. Some PMs can cause cancer.

How to Correct Incomplete Combustion

All kinds of issues can contribute to incomplete combustion in household or workplace appliances.

All too often, the reason an appliance begins to operate inefficiently is due to neglected preventative maintenance. Over time, buildup of dirt, debris, scale, soot, rust and other residue can impact the interaction between the heat source and the oxidant.

Blocked vents, flues, shutters or registers can prevent adequate oxygen from reaching the fuel source.

Malfunctioning pilot lights or ignition switches, compromised electrical wiring or heat exchangers and improper gas pressure can each contribute temperature troubles with the heat source.

Preventative maintenance service includes a safety inspection and basic cleaning that can address combustion issues ranging from dirt and debris to blockages and leaks, quickly correcting the combustion process so it once again works as designed.

NOTE: Our sister company, Shipton’s Heating & Cooling, specializes in correcting combustion issues in a wide range of residential and commercial appliances.

How to Clean Your Indoor Air After Incomplete Combustion

While an annual safety inspection and preventative maintenance service can restore combustion processes to their normal function, this service alone cannot address the byproducts now residing in your indoor air supply.

The Environmental Protection Agency recently released a concerning report stating that our indoor air is now up to five times more toxic than the air outside.

One major reason for this increase in indoor air toxicity is airtight construction. Without any natural leaks or cracks for indoor air toxins to escape, airborne toxins stay put and slowly build up inside our homes and workplaces.

This is why Ontario now requires new construction in the GTA to include the installation of a heat recovery ventilator to provide ventilation using mechanical processes.

Heat recovery ventilators are fantastic in airtight spaces – they can refresh and oxygenate your indoor air and help with seasonal humidity balancing. But they still can’t clean out toxins from your air supply.

For this, you need a specialized air cleaner. The two most popular indoor air cleaners are the ultraviolet air purifier and the HEPA filter.

An ultraviolet air purifier works to change the chemical composition of airborne toxins so they cannot harm you. UV air purifiers are especially effective against gaseous particles.

A HEPA (high-efficiency particulate air) filter works to trap airborne particulates and soot and remove them permanently from your indoor air supply. HEPA filters can remove particulates as small as 1/100th the size of a single human hair.

We always recommend scheduling a professional air duct cleaning service as a part of comprehensive indoor air cleaning to remove particulates trapped in your ducts.

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Contact us online or give us a call at 905-544-2470.

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