How do I know if I got cement powder in my hair?

This happens everyday and I think it's psychological but my mind thinks every where is a hazard to my hair like any suspisos thing that happens my mind instantly thinks it's cement powder and what happens is today well it was around 11 at night and there was this lady smoking in the nearly lit alley way I was walking through and I idjnt hear her walk behind me but my head thinks she quietly came up behind me and put cement powder on my hair anyways I came back home and took a really quick shower fast wash and my hair doesn't feel weird a little hot but nothing much so back to my question does my hair have cement powder and if so what are the symptoms? thanks Ive been suffering with this mental thing for seven years