What Pollutants Are Measured in the Air? - Carbon Monoxide

Carbon monoxide (CO) is among the most common air pollutants found worldwide. The gas is completely odourless, colourless and tasteless – but it can be deadly to both humans and animals if exposure occurs over a prolonged period. As such, monitoring concentrations of CO is absolutely essential in preventing accident or injury, especially in confined settings like homes and vehicles.

Although there are many natural processes which produce carbon monoxide as a by-product, the biggest contributors to its presence in the modern age are anthropogenic. As well as the exhaust pipes of passenger vehicles and the flue chimneys of power plants and other industrial sites, carbon monoxide is also produced when carbonaceous materials are improperly or incompletely combusted.

Where does carbon monoxide come from?

It’s estimated that some 60% of the CO emissions on Earth are as a direct result of human activities. The leading source is tailpipe emissions from cars, lorries and other road traffic, though rail and air travel also contribute a smaller share. Elsewhere, coal-fired power plants are linked to high levels of CO emissions, as are waste incinerators and certain types of industrial facility.

Other anthropogenic sources of CO emissions include land clearing and stubble burning in agriculture, as well as human-caused forest fires and other combustion of organic matter. 40% of CO emissions are caused by natural processes, such as those involving the ocean, forests and oxidation of hydrocarbons. Nonetheless, manmade sources of CO are the priority concern for environmentalists and climate scientists alike.

How does exposure to CO affect humans?

There is significant evidence demonstrating that CO has a detrimental and potentially deadly effect on the human body. When inhaled, carbon monoxide reacts with haemoglobin in the bloodstream to create carboxyhaemoglobin (COHb). When levels of COHb reach 10% in the body, the individual may begin to experience severe headaches, while dizziness, nausea and vomiting can follow.

However, if concentrations of COHb are allowed to reach 40%, the affected person may collapse or fall into a coma, while anything above 50% has the potential to kill. In fact, exposure to high levels of CO is one of the most common causes of atmospheric poisoning, which is why having a CO detector is now a legal requirement for landlords in the UK.

How does CO affect the environment?

Unlike other greenhouse gases like methane and carbon dioxide (CO2), CO does not directly contribute to global warming or climate change. Nonetheless, it is a precursor contaminant which, when exposed to sunlight, can create tropospheric ozone. Unlike its stratospheric counterpart – which is commonly referred to as the ozone layer – ground-level ozone is a damaging contaminant in its own right.

For that reason, atmospheric carbon monoxide levels are carefully monitored by air quality authorities such as NASA and the Environmental Protection Agency (EPA) in the US and the National Air Pollution Control Programme (NAPCP) in the UK. Anyone who is interested in learning more about how CO emissions (and indeed emissions of many other contaminants) are regulated should virtually attend the upcoming CEM conference next year, which promises to delve into the subject in far greater detail.