Asked April 27, 2015, 3:15 PM EDT

There is a white caustic looking powder that appears on our garage floor mainly in the winter. It appears to be coming from the cinder block back wall of the garage. The garage is situated with ground behind it 6 foot high pressing tight with shrubs and ground cover in it. I have sprayed this white substance with mold and mildew liquid remover. That almost removes the substance. I am concerned that the substance is dangerous to our health. Am I correct or not? What does it come from and is it dangerous? How should I remove it?Plus, is it efflorescence? Please advise me. Jack Beiter '52. PSU. Tel.610-688-6285; e-mail: Jackbeiter@e-finity.com

Chester County Pennsylvania

1 Response

If your concrete is untreated, I would suggest that it is efflorescence. You see it in the winter into spring because there is more moisture in the ground pushing up through the floor.

I would review this website on the topic.


Mold would be an issue if there were sufficient nutrients available. This should not be an issue on a concrete garage floor.