At this point, it's been coming out slowly. Of the four homes where contamination was originally found, one family has returned, but the other three have chosen not to move back, Janonis said. Most of the 25 homes that Nicor and its contractor have cleared of mercury have taken anywhere from a day to two weeks to decontaminate, said the EPA's Stimple. Mercury has been found in the living spaces of 15 homes, forcing families to evacuate during the cleanup. Collecting visible mercury is the first step in any cleanup operation.
Workers use a special sealed vacuum to pick up the mercury without spreading it further.
Floors where any mercury is found must be scrubbed three or four times with a sulfur-based cleaner that penetrates into the pores of concrete and binds with the mercury. To detect mercury levels in the air, workers use a handheld device that gives an instant readout. The same device, held near a porous object such as a chair or pillow, can show whether the object is contaminated. This should evaporate and dissipate any remaining mercury the previous steps might have missed. Finally, mercury measurements are taken while the home is heated to 85 degrees for eight hours to simulate a hot day when mercury might be vaporized.