This report follows an invitation by the Health and Safety Executive to open publication of a particular aspect of general interest in a programme of heavy gas dispersion trials conducted on a commercial basis for and reported separately to the Executive, namely the performance of the environmental instrumentation.

The report describes the types of sensor deployed for the various environmental measurements and meteorological assessments respectively made during and in-between the actual gas release experiments together with the techniques used to monitor their performance. The behaviour of certain transducers for which adequate samples of performance data were obtained have been examined using appropriate statistical analysis, the results of which are presented in the report.

Broad conclusions are drawn concerning the accuracy and reliability of the instruments so that better evaluation of any environmental records produced by them may made by those involved in detailed analysis, interpretation or application of the trials data.