The science behind the development and performance of reduced ignition propensity cigarettes

Abstract

A burning cigarette is a known cause of fire when mishandled. Studies into cigarette ignition propensity intensified after the US Cigarette Fire Safety Act of 1984. Extensive research has investigated the thermal properties of a smouldering cigarette, mostly away from any object of thermal contact or interference. To understand fire ignition, the thermophysics of cigarette’s burning tip has also been examined with and without a contact substrate. In either free or contact smouldering cases, oxygen diffusion through the cigarette wrapping paper has been found to be an important parameter controlling the rate of burn and the energy released. Research by the US National Institute of Standards and Technology led to a standardized test method to determine cigarette ignition propensity, and eventually regulations enforcing Reduced Ignition Propensity (RIP) cigarettes have been passed in all US states and other countries. Among the physical parameters of a burning cigarette related to its thermal energy release, circumferential bands applied to the cigarette wrapping paper that reduce air permeability or diffusivity during smouldering have become the main approach to produce commercial RIP cigarettes. Studies have been performed to ensure that RIP cigarettes have equivalent or lower mainstream smoke yields and biological activities as compared with their conventional non-RIP equivalents. The effects of the paper band properties (width, gap between the bands, type as well as the amount of the material applied) have been studied systematically to establish a manufacturability window. Studies on human smoking behaviour confirmed that RIP cigarettes matched closely their predecessors. The bands, as intended, alter the combustion temperatures during cigarette smouldering within the band. Further research into the interaction of RIP cigarettes with different types of commercial upholstery fabrics and materials should help to understand its mechanism of action in support of emerging post-implementation fire statistics.