On 29th June- 1st July 2022, Mr. Tomita who is graduate student 2nd grade presented his reserach results entitled "Ignition Characteristics of Propane/Air Mixture by Arc Discharges Generated at Gap of Electric Contact- Influences of Current and Rated Consumption Power to Ignitability-" at the Symposium on Safety Engineering 2022 via online. This is the experimental research to evaluate ignitability of propane/air mixture by arc discharges generated by usual handling of general appliances assuming that propane is used as the refrigerant of a room air conditioner and it is leaked into the living space. This is very complex phenomena which is influence by various factors like electrical elements, heat transfer, reaction,  and so on, thus, to understand whether ignition occurs or not is very difficult. However, we are finding a certain trend based on steady and polite experiment. We aim to develop the evaluation method for ignition considering advices received in Q&A in this meeting and a series of experments and numerical simulations which are going to be conducted in the future.