What happens if there is a real or threatening release of radioactivity in case of a nuclear accident?

If radioactive particles are released to the environment, they can be inhaled or ingested by humans. Furthermore, upon decay, they emit ionising radiation that can destroy or alter body cells. The official civil protection includes damage-limiting measures such as recommendations to

• remain indoors
• evacuate the potentially endangered area
  
• take high-dose iodine tablets in order to avoid intake of radioactive iodine into the thyroid glands of vulnerable population groups

or other measures, like food ban.