Vehicle Emissions fall into five main categories:
Carbon Dioxide (CO2), which is an inevitable product of burning a fuel which contains carbon (as all petroleum products do). CO2 does not pollute the air we breathe, but it is a main contributor to Global Warming and therefore has to be reduced. This means either using fuels containing less (or no) carbon (see the section on Alternative Fuels), or making vehicles and their engines more efficient – or both.
Carbon Monoxide (CO), which is produced when a carbon-based fuel is burnt incompletely. In high concentrations it is poisonous and has to be controlled. It can be reduced by more efficient combustion in the engine (so that CO2 is produced instead of CO) and further reduced by oxidising after combustion, in a Catalytic Converter. [2xCO + O2 = 2xCO2]
Hydrocarbons (HC), also known as “Volatile Organic Compounds (VOC) are really unburned fuel. They can be a problem to people with breathing difficulties and are a contributor to “Photochemical Smog” in certain climatic conditions. They can be reduced by more efficient combustion in the engine and further reduced by oxidising after combustion, in a Catalytic Converter. . [4HxCy + (x+4y)O2 = 2xH2O + 4yCO2]
Oxides of Nitrogen (NOx) are produced when air (which is mainly a mixture of Nitrogen and Oxygen) is heated as it is in an engine. NOx is a contributor to both Photochemical Smog and Acid Rain and can be an irritant to the lungs. Unlike CO and HC is cannot be removed by oxidation. The opposite process – the removal of Oxygen, known as “Reduction” is necessary to convert it back to Nitrogen and Oxygen.
Particulate Matter (PM) is very small particles, mostly of unburnt Carbon.
Car Emissions Testing Facts: everything you need to know about emissions testing
The new CarEmissionsTestingFacts.eu website provides a fact-based overview on everything related to the test of car emissions in Europe.
Through various infographics, this online Platform provides clear answers to the most common questions about emissions testing, with each explanation complemented by in-depth background information. Questions include: what emissions are, how they are measured (NEDC, WLTP and RDE) and the progress that has been made reducing them.
Based on facts, this website also aims to inform the reader correctly and address common misconceptions about the car industry and emissions.