Vehicles Emissions

Air quality pollutant emissions
These are emissions such as particulate emissions and NOXemissions that can be harmful to the environment and to human health. These emissions are regulated by the European Union (EU) so vehicles must meet specific, stringent standards known as the 'Euro' standards before they can be sold in the UK or Europe.

CO ₂ emissions
Carbon dioxide (CO ₂ ) is a greenhouse gas and is produced by cars as they burn fuel. The more fuel burned the more CO ₂ is produced which contributes to climate change. CO ₂ emissions are not currently regulated by the EU but under voluntary agreements vehicle manufacturers in the EU aim to reduce CO ₂ emissions from the cars they produce.

Particulates or Particulate Matter (PM)
These are the elements of a car's tailpipe emissions that are either solid or liquid droplets. Most particulate matter is solid carbon particles and most is too fine to be detected by the naked eye. Particulates can be harmful to respiratory and cardiac functions.

NOX emissions
NOX is a generic term for nitric oxide (NO) and nitrogen dioxide (NO ₂ ) which are formed when nitrogen and oxygen react with each other at high temperatures in a car engine. It is a mixture that can be harmful to respiratory and cardiac functions as well as having damaging effects on crops. NOX emissions are regulated by the EU so vehicles must meet specific standards.

Tailpipe emissions
These are emissions that come out of a car's exhaust pipe and are measured when a new car is tested to ensure that it meets the necessary standards needed for sale in the UK or Europe. These emissions are also known as tank-to-wheel emissions.

Well-to-wheel emissions
As well as measuring the emissions that come out of a car's exhaust pipe, it is also possible to measure the total emissions that are generated from the production of the fuel through to the burning of the fuel in the car's engine. This is particularly relevant for biofuels because, although biofuels don't produce less CO ₂ emissions when they burn, their 'lifecycle' is greener because the crops themselves remove CO ₂ from the atmosphere when they're growing.

Diesel Particulate Filter (DPF)
This is a fine filter positioned in the exhaust system of a diesel engine in order to remove particulate matter.

Emissions testing
A process that involves the testing of a vehicle in laboratory controlled conditions to assess the emissions they produce in order to achieve European Type Approval.

European Type Approval
The approval of a vehicle for sale in the European Union following testing of a small, representative sample of that model to ensure conformity with the regulations governing emissions, safety, and other relevant issues.

Euro standards
Euro standards are the air quality pollutant emission standards that all new cars have to reach before they can be sold in Europe. These standards have been in place since 1970 but have become more stringent over time. The first Euro standard for cars required petrol engines to be fitted with catalysts and was known as Euro 1. This was followed by Euro 2 then Euro 3. The current Euro standard for cars is now Euro 4. Euro 5 will become compulsory for new cars from 1 January 2011.