DE (dirty electricity) is the low frequency (1 Hz to 60 kHz) electrical noise in the wiring of a house that radiates throughout the house.
DE has been found to have health impacts on people exposed to it and there are devices that some purchase to decrease this damage.
Smart Meters and other modern devices create DE when they change the high voltage to lower voltage. Great technology but it has a very sinister downside.
Here is an interesting article published in 2011 that details the problems of DE from Smart Meters. It even suggests that California, as well as all other jurisdictions will suffer huge financial troubles in the near future with falling real-estate prices and huge law suits.
See this fantastic article at http://eon3emfblog.net/?p=2180
Also see http://www.electrosmogprevention.org/public-health-alert/smart-meters-switching-mode-power-supply-dirty-electricity/