Why does white powder spray out of a bush when you brush past it?

Question

I was walking down the sidewalk and happened to brush past not one but THREE bushes; a ploom of white powder came out of each one. Could it possibly be a lot of really small white spores? Or maybe someone poured plaster in the bushes? I'm a little worried since I breathed some of it in...

Answer 1

It was probably just leftover dried out paint, that was left on the brush.

Answer 2

Plaster isnt white. It sounds more like Sarin you breathed in.