Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, whether there are limits on (a) individual pollutants and (b) emissions from appliances that can be granted exemptions under the Clean Air Act 1993.

Testing appliances for exemption focuses on smoke emissions when different fuels are burnt. Exempt appliances are accompanied by a list of suitable fuels for use. For each fuel, the appliance must not exceed emissions of 5 grams of smoke per hour (5g/h).

The British Standard PD6434:1969 is used to assess whether appliances can be granted an exemption under the Clean Air Act 1993. This standard sets the protocols and methods for the testing for assessment of smoke emission.