Environment Agency
Details
Before you start make sure you have the information you need to enter into the tool. See the guidance Specified generator: when you need a permit.
If the emissions screen out as low risk you can apply for a simple bespoke permit. You will need to provide a completed copy of this tool with your application to demonstrate you have applied for the correct permit.
If the emissions do not screen out as low risk you will need to apply for a complex bespoke permit. Complex bespoke permits require a site specific air quality modelling assessment. See the guidance on how to do detailed air quality modelling for emissions from specified generators.