Where can I find an emissions factor for a particular activity?
A comprehensive set of emissions factors applicable to the UK can be found on the UK Emissions Factors Database (UK EFD). Available from here
What is an Emission Factor?
An emission factor is the relationship between the amount of pollution produced and the amount of raw material processed or burned. For road traffic it is the relationship between the amount of pollution produced and the number of vehicle miles travelled. By using the emission factor of a pollutant and specific data regarding quantities of materials used by a given source, it is possible to compute emissions for the source. This approach is often used in preparing an emissions inventory.
What are emission inventories?
An emission inventory is a comprehensive listing by source of air pollutant emissions. They cover a specific geographical area and a specific time period. The UK NAEI estimate national total emissions of a wide range of air pollutants for each year since 1970. For further details please go to the report section of the NAEI website and download the most recent UK Emissions of Air Pollutants report. | 
