Dust explosions are recognised as very major industrial hazards. A meticulous attention should be engaged towards their analysis, prevention and control. A number of causes can trigger a dust explosion. Static electricity is one of the ignition sources. The current safety standards for determining electrostatic ignition hazards of dusts, such as electrical resistivity and charge decay time, are currently used in the process industries. Nevertheless, the standardisation of the proposed protocols suffers mainly from the looseness of a clearly definite description concerning the experimental conditions. The content of the paper is focused on the influences of the time, the voltage, the temperature, the relative humidity and the compaction of the dust on the two precedent parameters. The obtained results clearly show the necessity to improve the current standards. A proposition to complete the conditions of the normalised protocols is suggested. (c) 2007 Elsevier Ltd. All rights reserved.