One of the most important chemical reactions is combustion. It requires three things: a fuel, an oxidant and a source of ignition.
For a campfire, the fuel is the wood you are using, the oxidant is the oxygen in the air around us and the source of ignition is usually a match or lighter.
In the case of an automobile engine, the fuel is now gasoline or some equivalent material, the air provides oxygen and the source of ignition is a spark plug.
The chemical reaction is pretty much the same. The combustion of every hydrocarbon compound uses oxygen to produce carbon dioxide and water if everything is in balance. If the balance is out a little bit, then the reaction might have too little oxygen and soot is generated directly. Or the reaction might be tweaked to get reactive hydrogen instead of water.
The average vehicle does produce a number of other byproducts during combustion. Various oxides of nitrogen emerge from the tail pipe. They provide the distinctive purplish colour to smog and account for some spectacular sunsets in the Lower Mainland.
These compounds are also a health hazard. In sufficiently large quantities, they can kill but even at low doses they are potential carcinogens. Fortunately, they are also reactive and water soluble. Generally we don't have to worry about NOx unless we live in a city with excessive smog.
Ozone is another by-product of combustion. It results from the combination of molecular oxygen with a single atom of oxygen making this allotrope. Ozone is also produced while welding and a number of industrial processes.
In water, its oxidizing power allows it to destroy contaminants so it is used as a disinfectant. In the stratosphere, it forms in a protective layer which shields the Earth from ultraviolet radiation. But at ground level, ozone is a respiratory irritant which can lead to headaches and nausea. In high enough concentrations, it, too, is deadly.
Carbon monoxide is another consistent by-product of the internal combustion engine. This gas is deadly as it preferentially binds to hemoglobin blocking oxygen uptake. Too much carbon monoxide results in asphyxiation and death.
Tailpipes are also a source of particulate matter. PM 2.5 and smaller particles are able to bypass the hairs in our lungs intended to sweep away solid material. They settle on the surface of the lung, acting as irritants and leading to a variety ailments including inducing lung cancer. Further, the particles usually host a slew of poly-aromatic hydrocarbon compounds resulting from incomplete combustion. These are known carcinogens.
All of these compounds are found in varying amounts in automotive exhaust. For example, carbon monoxide makes up between one and two per cent of tailpipe emissions, depending upon the engine type and its operating condition. A well-tuned engine generates fewer emissions. It also depends, to some extent, on the time of year and the composition of the gasoline being used.
But it is carbon dioxide we mostly concern ourselves with when considering the effects of emissions from transportation. Every liter of gasoline we burn generates about 2.3 kg of carbon dioxide. For diesel fuel, it is 2.7 kg per liter. Vehicles account for 20 per cent of our carbon dioxide emissions.
At this time of year, though, people tend to idle their cars. It is both unnecessary and wasteful. A car's engine doesn't need to be warmed up for 10 minutes before being driven. Idling in the drive through line is nothing more than a waste of gasoline and a good source of greenhouse gases.
It is hard to find accurate data on just what "per minute" emissions are for an idling engine but Environment Canada estimates if we all idled for three minutes less each day we would reduce carbon dioxide emissions by 1.4 million tonnes per year.
Perhaps more to the point, we would save 630 million litres of gasoline which would directly impact our wallets.
I have heard the arguments against turning a car's engine off - it will cool off, it takes more fuel to start a cold engine, turning an engine on-and-off will burn out the starter motor - but these really don't hold water.
The amount of time it takes to get out of a car, go into a Tim Horton's to get a coffee, and then get back into your car is far less than the time it takes for the engine to cool down. Try it some time.
Idling an automobile contributes to climate change as well as emitting a wide variety of noxious substances. While in a city like Prince George we don't generally generate enough vehicle smog for it to be truly noticeable, the cumulative effects of particulate matter and gases are not healthy either. Especially when they are unnecessary.
After all, idling doesn't get you anywhere.
