The Dust Explosion Committee of the Association of Powder Process Industry and Engineering (APPIE) of Japan has acted to establish the standard for the member of the Association. Two testing methods have been authorized by the Association. The methods are established to evaluate sensitivity and severity for dust explosion. The ignition sensitivity is evaluated by the minimum explosive dust cloud concentration. Tapping sieve equipment and a strictly-specified Hartmann-type explosion tube have been selected as the testing apparatus. The tapping sieve equipment is applied to measure the minimum explosive concentration by forming a dust cloud supplied from a sieve on the top of the explosion chamber. The Hartmann-type tube is used to investigate roughly whether the test powder is explosive or not. A lot of explosion tests had been carried out to standardize the equipment and evaluate the sensitivity. This APPIE standard is being revised. Along with the ISO standard for explosion severity, Research Institute of Industrial Safety, the Ministry of Labour published a Guide to Test Method for Explosion Pressure and Rate of Pressure Rise for Combustible Dusts in 1994. Based on this Guide. The APPIE Committee has made the draft for the member. These standards and drafts are aimed to be the Japanese Industrial Standard (JIS). No other similar standard exists in Japan. In the present paper, technical data and explosion statistics which are the background of the APPIE standard for the ignition sensitivity are to be described. (C) 2000 Elsevier Science Ltd. All rights reserved.