Compliance with LIP regulations or product safety standards is achieved by using a specially designed cigarette paper that includes narrow bands of a natural substance, causing a reduction in air flow in these discrete regions. The bands therefore act like ‘speed-bumps’ and increase the likelihood that a cigarette will extinguish when burning through these zones if left unattended.
LIP paper works by reducing the air permeability/diffusivity of the cigarette paper in discrete banded regions along the cigarette rod in order to decrease the oxygen supply to the burning coal. This results in slower smouldering rates and a higher probability of self-extinguishment when the cigarette is not being puffed on. The bands are generally 5 – 7 mm wide with a spacing of 18 – 20 mm.
The movement of a gas through a membrane due to a concentration gradient only across a membrane. By analogy, this can be compared to the smouldering process, as occurs during LIP testing – schematic below.
Diffusion by gradient
The movement of gas (air) through a membrane as a consequence of a pressure differential being applied across the membrane. This can be compared to what happens when a cigarette is puffed, as occurs during human or machine smoking.
Lower Ignition Propensity (LIP) regulations have so far been introduced in the US,  Canada, Finland and Australia and were introduced in the remainder of the EU as a general product safety standard on 17th November 2011. This standard has been mandated by the EU and applies to all manufactured cigarettes sold within its borders. The standard is intended to increase the chances of cigarettes self-extinguishing under controlled, legislated laboratory conditions. The aim is reduce the chances of accidental fires being caused by burning cigarettes when left unattended. There is some debate however, on how effective this solution will be in a real world environment.
LIP cigarettes are tested under strictly controlled conditions, following the protocols detailed in either the ASTM E2187-09  or ISO 12863:2010  test methods. In these test methods, cigarettes are manually lit using an electronic cigarette lighter in order to establish a uniform burning zone. During this lighting phase, not more than 5mm of the tobacco column is burnt. The lit cigarette is then placed in a cigarette holder within a standardised test chamber with an open chimney vent, until 15mm of the tobacco column has burnt. At this point, the cigarette is placed horizontally (with the cigarette paper seam facing upwards) on a stack of 10 Whatman No. 2 (or equivalent) filter papers, which are also located within the standardised test chamber in a circular holder. The cigarette is held in position by two 17mm (± 1mm) metal pins which protrude from the rim of the filter paper holder.
A cigarette is deemed to pass the test if it self-extinguishes (i.e. ceases to burn) before smouldering down to the filter tipping paper (for filter tipped cigarettes) or before burning down to the metal pins (for non-filter tipped cigarettes). According to all current LIP regulations, a cigarette batch is certified to have passed the test if 75% or greater of the cigarettes (normal sample size = 40) self-extinguish in this manner.
Below is an example of a pass (left) and a fail (right) result using the ASTM E2187-09 protocol.
Prior to testing, the cigarettes and filter papers are conditioned at 23 ± 3 °C, 55 ± 5 % relative humidity for a minimum of 24 hours and 7 days respectively. These are also the conditions under which the cigarette testing must be performed. Each individual testing laboratory verifies the performance of its test equipment and operator(s) using a reference cigarette whose ignition propensity has been established (using either the ASTM E2187-09 or ISO 12863:2010 test methodologies).
The following information relating to LIP may be of interest. The data have been presented at scientific forums and are available to view via the library or the associated link.