asked Her Majesty's Government:

Further to the Written Answer by the Minister for the Environment, Mr Phil Woolas, on 5 February (Official Report, Commons, 983W), why data on sulphur dioxide emissions take two years to process, verify and enter onto the National Atmospheric Emissions Inventory. [HL3012]

Defra published the 2006 results from the National Atmospheric Emissions Inventory (NAEI) for UK air pollutants on 13 March 2008. Therefore, the time lag between the end of 2006 and publication of the results was a little over 14 months.

There is a vast amount of data that needs to be collected and compiled in order for the NAEI to be produced, and unfortunately this takes time. A number of important datasets are required, such as the Environment Agency's pollution inventory. This provides emissions from around 2,000 major point sources in England and Wales and, therefore, extensive compilation is required following the deadline of the end of April 2007 for operators to supply data. The NAEI also relies heavily on the Department of Business, Enterprise and Regulatory Reform's digest of UK energy statistics, which is normally only made available at the end of July. The digest contains a comprehensive picture of energy production and use over the past five years and, therefore, this dataset takes a significant time to compile. There are also many other datasets required, some of which are not available until the autumn. The aim is to have all the input data available by the end of September at the latest, so that compilation can commence.

It then takes approximately three months to compile the emissions inventory, as it is a complex task. The NAEI provides estimates of emissions to the atmosphere for 44 pollutant species and, in addition to the latest set of data being added to the inventory, the full-time series is updated to take account of improved data and any advances in methodology used to estimate the emissions.