The guidelines for air exchanges is Health Technical Memorandum 2021 Ventilation in Healthcare Premises. Endoscopy procedure rooms require 10 air changes an hour (10ACH).
The Health Technical Memorandum 03-01 – ‘Specialised ventilation in healthcare buildings’ is published in two parts, Part A and Part B
https://www.england.nhs.uk/publication/specialised-ventilation-for-healthcare-buildings/
JAG have recently included a reference to ventilation in the environment guidance to ensure that services are ensuring that ventilation and heating systems are regulated to comply with health building recommendations (specifically in the case of ventilation to HTM 03 – 01) and the supplementary COVID guidance further recommended that services formally assess the ventilation and filtration in each procedure room.