As TM21 largely contains general guidance, rather that strict rules, it is expected that the designer or services engineer would be familiar with the requirements within TM21 and be able to determine which sections are relevant for the development in question.
The main areas to consider in relation to TM21 are:
• Provision of filtration
• Positioning inlets to minimise impacts of traffic pollution
• Positioning inlets to minimise impacts of other local sources of pollution
• Positioning inlets to minimise recirculation from ventilation exhausts
Confirmation is required that each of these items (and anything else the designer/engineer deems relevant) has been considered in determining the location of air intakes. Suitable evidence may for example be in the form of a short report with diagrams indicating the proposed location of intakes, with respect to sources of pollution and with reference to the relevant parts of TM21.