Unfortunately electrical shielding can also act as containment and provide additional paths for EM waves to resonate.

I prefer to simply stay away from high-power EM sources like in cities and near radio or cellular towers. Keep your phone on airplane mode, when using cellular locate the phone at least 10' away (or a minimum of an arm's length) and use a bluetooth headset for phone calls, turn off NFC when not using it, only use wifi at home, turn down your wifi router's power level to the minimum necessary, locate your wifi router away from bedrooms, kitchen table and the living room, plant trees and shrubs around your house to absorb EM, when replacing your roof make it steel or aluminum panels and be sure its well grounded with braided copper straps (tin foil hat for your house), avoid metal siding as it can act like a "microwave oven", locate your house in a topographic depression, and move out of the city. EM is only one of many carcinogens and endocrine disruptors that you are exposed to in densely populated areas.