"A few weeks after we had L Seven out to our condo, we called them back because we noticed a fine white powder/residue collecting especially in our babies room. It seemed as though it was in the air so we though maybe it was from the air vents becuase it was everywhere (Curtains, walls, mirrors, artwork). They called back right away and scheduled an appt with us the very next day. Kerry re-checked our ducts, ac/heat unit, as well as the hose in the attic to see if there were any tears in it. He put up filter paper on the vents and said to try that for the next few days to see if that helped. If not call and he would come back. A few days later it was better but still collecting so we called him back. He was back to the house and re-checked everything. We then wondered if this could be coming from the humidifier we had in our babies room. Found out that it did seem like that was what it likely was. I was so impressed with L Seven and Kerry."