I was cycling this past weekend and while stopped at a light I noticed a pea sized spot of what appeared to be dried blood on my arm. I immediately grabbed my water bottle and rinsed it off and then continued my ride. Upon reaching home I checked the area an noticed no cut or wound anywhere near the area and when I cleaned the area with rubbing alcohol it did not sting which leads me to believe the blood was not my own. I live in an urban area (downtown Dallas) and pass many people on the streets and trails as I ride, some of whom are homeless. The winds were high that day so the blood could have been blown from someone nearby onto me as I passed by them. If the blood was from someone who is HIV positive, would I be at risk for transmission given the fact the random blood landed and dried on intact skin? In terms of duration of exposure I have no idea how long it was there, I had been riding for quite a while at that point. Thanks for any help you can provide!