Mechanical ignition sources are important under the ATEX Directive, but little is known of the risk associated with them. Characteristics of sparks and hot spots produced by impact, friction and grinding are to be measured. Simulated ignition sources with the same characteristics will be used to measure the sensitivity of explosive environments to ignition and this sensitivity will be characterized in relation to standard measurements of the ignitability of the explosive substances. The results of the two parts of the experimental programme will be combined to categorize equipment intended for use in potentially explosive environments on the basis of the type of mechanical ignition sources likely to arise from a specific design and method of operation and the environments likely to be ignited by these sources. A proposal for a methodology for inclusion in European Standards on preparing Ignition Hazard Assessments will be produced.