How do i know if i have i risked infection?

Risk of infection: Not sure what type of infection you are concerned about but usually we look at inoculum (how many organisms were you exposed to), infectivity (how many organisms does it take to cause an infection); duration of exposure (the longer the exposure the higher the risk); immune status of host (eg: nutrition, presence of co-infection, cancers, medications that suppress the immune system); good/bad luck.