My car is in a (well ventilated) underground car park. Since the penultimate week was practically continuous around the -10 degrees and it was all at once about 20 degrees last Sunday, large drops of condensed water formed on the concrete ceiling of the garage, which of course also dripped onto the car. Meanwhile, the ceiling has dried up to a large extent again. After that, there were large white spots everywhere on the paint. I was in an SB box yesterday morning and sprayed the car. Last night I drove through the wash road and the stains were still to be seen. Only after the use of detailers they disappeared. My question is: Are these harmless residues from the concrete water, or can this become a serious problem for the paint? Who knows about it?