FAQ: Can humans ever smell carbon monoxide? Can dogs smell carbon monoxide?

Short answer: The byproducts of incomplete combustion, which is what creates carbon monoxide can be smelled, even though the CO itself has no odor. Dogs will smell unburned fuel well before humans will.

Can dogs smell carbon monoxide? Shown here is Hannah the Hero, a dog who saved her families life because she could smell the subtle smoke that accompanies high levels of CO poisoning from gas fired appliances.

Gordon Johnson: Can you ever smell carbon monoxide.

Griff Winthrop: You can’t smell carbon monoxide. But you can sometimes if it’s high enough concentrations in the ambient air, you oftentimes will be able to smell the hydrocarbons that are being unburned by the appliance that is kicking out the carbon monoxide.

Gordon Johnson: Can dogs smell carbon monoxide?

Griff Winthrop: I think dogs can smell carbon monoxide.

Gordon Johnson:  I think what’s happening is at any time you have carbon monoxide, you have some smoke. All right. Natural gas, propane burn very cleanly. So with normal combustion, you don’t have any visible smoke. And very, very little that can be smelled even by animals.

But as soon as you start to create carbon monoxide in any significant level in the exhaust, there is going to be more and more smoke, even in natural gas appliances. S dog smell is thousands of times more sensitive than humans. And because it’s so sensitive, they probably ignore a fair amount of things that we might think would be concern.

But at some point, probably 10% of what we can start to smell it, the dogs will start to realize that there’s a risk at 4000 to 5000 parts per million. The human nose can probably detect it. So perhaps 40 or 50 parts per million that dog starts to be wondering, and if the dog is whining and you don’t feel good, you’re all likelihood is going to be carbon monoxide.

Now, dogs may die sooner. They may. We’ve seen cases where the dog died. We’ve seen cases where the dog survived. So I don’t know they don’t necessarily die sooner. That would largely have to do probably with their size and how fast they’re breathing. But if you smell something, it may not be a gas leak, which is typically a natural gas leak. It may, in fact be the exhaust that goes with carbon monoxide.