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  • Writer's pictureNikki James Zellner

The breakdown: Understanding carbon monoxide sources vs. carbon monoxide spreaders

Updated: May 1, 2021

When you're an advocate, you're an unpaid educator.

So I'm going to put on my teaching hat for a minute here and help my students out.

But first, the science:

Carbon monoxide (CO) gas is produced when fuel burns incompletely because of insufficient oxygen. During incomplete combustion, the carbon and hydrogen in the fuel combine to form carbon dioxide, water, heat, and deadly carbon monoxide.

In properly installed and maintained appliances and equipment, the fuel burns clean and produces little to no carbon monoxide. Therefore, anything that disrupts the burning process burners or results in a shortage of oxygen or burners, can increase carbon monoxide production.

Wood, coal, and charcoal fires usually produce carbon monoxide, as do gasoline engines.

So, back to layman language, there are CO sources and there are CO spreaders.

A source is exactly what it sounds like: the exact piece of equipment, or vehicle, or burning fire that is causing the by-product of incomplete combustion: carbon monoxide.

In a school, CO sources are things like (but not limited to):

• Boilers or furnaces

• Gas-fired kitchen appliances

• Construction equipment like concrete saws

• Welding equipment

• Bunson burners

• Backup generators

• Gas-powered cleaning equipment like floor polishers

• A school bus, delivery vehicle, or parent's car in the car line

• A fire burning nearby

• Propane-fueled equipment like space heaters, grills

CO spreaders are pathways, or in simpler terms, the ways in which deadly gas can get from the place it started to the place it shouldn't be.

In a school, CO spreaders are things like:

• HVAC systems – more specifically, their fans, ducts, vents, exhaust/intake pipes, and access doors; issues, blockages or down-drafts with any of these create the ability for CO, that should be exhausting through a dedicated pathway, to instead "leak" into areas it shouldn't

Improper installation of or deterioration of equipment – this is a prime example of why inspection of equipment should be happening more frequently that once or twice a year, and should inspected by qualified inspectors and maintenance personnel

Unsealed construction or cleaning areas – Barriers such as walls can slow down carbon monoxide pathways, but they can't stop it entirely. Carbon monoxide can seep through drywall and other porous materials. If construction or cleaning is happening on your property, and is using combustion equipment, you should seal off and properly ventilate the area in use.

Side note: An AC unit (such as a rooftop AC) can't CREATE carbon monoxide, but it can be the place the CO is "leaking from" – causing many to misidentify it as "the source" – it is, in fact, the "spreader."

How carbon monoxide moves

The "flow" of any gas is typically based on two primary factors:

• Hot air rises

• Airflow moves toward the point of suction

Carbon monoxide weighs relatively the same as regular air, so it will disperse relatively evenly up or down, unless there's a point of "flow."

Think of a room, or any space that's not outdoors, like a vacuum cleaner. If CO has a place to go – it will. AND, it can seep through drywall ... making it extra tricky.

Where do you want CO to go? OUTSIDE.

To get distributed outdoors.

Away from air intake systems.

Away from vents that take it to other indoor areas of the building.

Away from porous materials or open pathways.

This is why maintenance and frequent inspection of not just equipment, but pathways, are important.

This is why exhaust fans and vents, the filters you use, and the cleaning of them, is so important.

If your intake/exhaust vents are too close together, if a little birdie builds its nest in a vent or duct, or if there's the smallest gap where there shouldn't be one... well, Houston, we've got a problem.


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