TR/19 update--key concerns addressed.

With trade association for the heating, ventilating, air-conditioning, and refrigeration sectors, the Building and Engineering Services Association (B&ES), having recently updated its 'TR/19' guidance document--dealing with the internal cleanliness of ventilation systems--Health Estate Journal (HEJ) asks Richard Norman (RN), chairman of the Association's Ventilation Hygiene Group Branch, and MD of specialist ventilation cleaning services provider, Indepth Hygiene, about the changes, and why the revisions were needed.