4.1.1.1 Temperature 4.1.1.2 Relative Humidity 4.1.1.3 Air Velocity 4.1.1.4 Dust Composition 4.1.1.5 Dust Concentrations 4.1.1.6 Orientation 4.1.1.7 Duration 4.1.1.8 Operation During Test 4.1.1.9 Removal of Dust Accumulations