just moved into a townhouse and in the front yard the patio's concrete is just like brushing away ! its already in bad shape and the winds get high around here so we are concerned about the kids and ourselves if the powdery white/grayish substance is bad for you ? u can drop a ball and a puff of powder comes up in the air ! want to cover with rug or something temporary to prevent anymore exposure to it whether its healthy or not ! the pee gravel they use is just falling apart as well . maybe 60 sq ft is affected and as deep as 1"in. the whole surface is affected ! Mexico