All councils in England have to assess air pollution in their area and decide whether it meets government standards.
Some industries must be authorised by either the Environment Agency or the local council, who authorise the amount of pollution that can be
emitted from the site.
The government sets four basic levels or bands for defining air pollution: Low, Medium, High, and Very High.
Results from Kirklees monitoring are given to the Press Association each day and normally are in the Low category.
A review and assessment of air pollution levels was completed in January 2001.