Accidental ignition of plant material deposits – case study

Fire safety in storage of plant and agricultural materials is a major concern worldwide, with significant economic implications and potential risk to human lives. These materials, such as hay, straw, cereals, wood or compost, are organic fuels with a porous structure, which facilitates heat retention and a certain intrinsic reactivity to oxidation. Therefore, they are susceptible to two distinct but equally dangerous phenomena: self-ignition and ignition initiated by external sources. Autoignition (or spontaneous combustion) is a complex process resulting from the internal accumulation of heat generated by exothermic reactions at low temperatures, below the classical flash point, and is highly dependent on the amount of material stored. In addition to autoignition, deposits of plant materials are also extremely vulnerable to accidental initiation from external ignition sources. Due to their fibrous nature and high specific surface area, these materials exhibit a relatively low minimum ignition energy and an increased tendency for rapid flame propagation once initiated. The most common sources of accidental ignition include sparks (from machinery, electrical short circuits, electrostatic discharges), hot surfaces, atmospheric discharges (lightning) and, in particular, incandescent objects such as lit cigarettes, matches or hot ashes. The high temperature of a cigarette tip (which can reach 500-800°C during inhalation and 400-600°C when at rest), combined with prolonged contact and the potential for natural convection through fibrous materials, can initiate a smoldering fire that can slowly but surely develop into a full-blown fire. In this paper, an experiment was conducted to identify the initiation capacity of a lit cigarette from a plant material deposit (dried leaves).