I saw a recent question submitted where the person was seeking answers to particle physics due to the debilatating illness of OCD (obsessive compulsive disorder). I wondered whether somebody could answer this question in relation to airborne particles. In for example an work/office environment are particles passed between humans i.e. people in that office and if so at what sort of volume? Is it the tiniest of specs or are you completed covered? The main areas of concern are for example dust mites and human skin cells and the air people breath out. Are you covered in other peoples breath that they are exhaling?