Skin resistance level

Note. HCI = human-computer interaction SCR = skin conductance response SRL = skin resistance level SRR = skin resistance response SRT = system response time NS.SCR = nonspecific skin conductance response. 

Current introduced to the body is often held to low values by the electrical resistance of dry skin, between 5,000 and 10,000 ohms (Kantrowitz, 1972). Wet skin will have electrical resistance levels as low as one-tenth of this. Where electrical leads are introduced subcutaneously, resistance falls to 10-50 ohms, and this situation is potentially dangerous. Subcutaneous leads are used for heart pacemakers, artificial hearts, transcutaneous electrical neural stimulation (TENS) to block pain, and subdural leads for the control of Parkinson s disease. 

V. Savchenko, Monitoring of an operator s vigilance level by skin resistance response, Control Engineering Practice, vol. 4, no. 1, pp. 67-72, 1996. 

Sometimes it is important to reduce skin resistance to the lowest possible value, as in EEC recordings, to detect microvolt-level signals. In this case, the skin barrier is punctured by using a pinprick or sometimes drilling with small abrasive tools. The abraded region or puncture fills up with interstitial fluids and immediately forms a low-resistance pathway to the body interior. Although effective for improving bioelectrode performance, it is often not popular (for obvious reasons) with most subjects or patients. 

Pi, J. et al., Low level, long-term inorganic arsenite exposure causes generalized resistance to apoptosis in cultured human keratinocytes Potential role in skin co-carcinogenesis, Int. J. Cancer, 116, 20, 2005. 

Level A protection should be worn when the highest level of respiratory, skin, eye, and mucous membrane protection is needed. This level consists of a fully-encapsulated, vapor-tight, chemical-resistant suit, chemical-resistant boots with steel toe and shank, chemical-resistant inner/outer gloves, coveralls, hard hat, and self-contained (positive pressure) and SCBA. 

Level C protection should be selected when the type of airborne substance(s) is known, concentration is measured, criteria for using air-purifying respirators are met, and skin and eye exposure are unlikely. It involves a full face piece, air-purifying, canister-equipped respirator and chemical-resistant clothing. This level of protection provides the same degree of skin protection as Level B, but a lower level of respiratory protection. 

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