Effect of Human Activities and Environmental Conditions on Electrostatic Charging

The generation of electrostatic charge is considered for the cases of standing up from a chair and removing a garment at dew points with temperature and relative humidity (RH) of -13.1 °C (5 °C, RH 25%), -10 °C (27 °C, RH 8%), -8.9 °C (18 °C, RH 15%), -1.7 °C (38 °C, RH 8%), 5 °C (27 °C, RH 25%), 5.6 °C (18 °C, RH 45%), and 13.9 °C (27 °C, RH 45%). Using ESD mitigation shoes/floors rather than non-ESD can reduce the voltages by a factor of ∼2 to 5 for garment removal and ∼2 to 7 for standing up from a chair. For the garment removal, the charge voltage will drop to 100 V within ∼0.5 to 6 s and within ∼1 to 30 min when ESD and non-ESD mitigation shoes/floors are used, respectively. For the standing-up form a chair, the corresponding times are ∼0.5 to 3 s and ∼1 to 4 min, respectively. For the extreme case at 22 °C, RH 5%, the voltage can surpass +/- 20 kV. Finally, it is shown that the voltages a person will charge up to may vary by +/- 30% just because of different capacitances to ground. Residential home settings will lead to the highest voltages (60 pF test person to ground, U.S. wood frame house), while standing on a concrete floor only half of the voltage may be reached (120 pF).