... a system in which samples of known but undisclosed content are introduced into a laboratory's routine testing procedure.

All laboratories offering a quality microbiological examination service must implement a quality assurance system. An effective system contributes to cost-effective laboratory management, and eliminates preventable inaccuracy. Health Protection Agency EQA schemes provide laboratories with an independent assessment of the quality of their microbiological services.

The Health Protection Agency is an independent organisation dedicated to protecting people's health. It brings together the expertise formerly found in a number of official organisations and works in partnership with the National Radiological Protection Board.