If there has been an actual or suspected exposure to a chemical or radiological agent, local government officials will set up screening and decontamination locations. This is a place where you will be screened for any agent you may have been exposed to.
If contamination is determined, you will be escorted through a decontamination process. You will then be given some form of identifier that indicated you are now free of contamination. Do not return to a contaminated area until it is determined safe by authorities, because you may have to go through the decontamination process again.
If you have further questions about decontamination procedures, please contact your local emergency management agency or local fire department.