When a nuclear accident involves a large amount of radioactive aerosols, the subsequent fallout may contaminate the soil and water of affected areas. In this case, public authorities should implement specific protective mea­sures, to protect the public in accordance with international standards, from contamination through foodstuff and water consumption and inhalation of airborne aerosols deposited in soil. It is likely that these actions would have to be continued for a long period. Management of these situations is usually beyond the scope of the nuclear emergency plans, because they could involve the intervention of a wide range of government institutions and require special political and economic decisions.

Lessons learned from the aftermath of the Chernobyl accident show that a relevant fraction of the total dose produced by a large nuclear accident arises from chronic exposure. Chronic exposure is mainly produced by direct exposure to soil contamination, contaminated food consumption and inhalation of radioactive airborne materials. Reducing long-term exposure could require implementation of hard countermeasures such as the long­term health care of victims, modification of agricultural practices and strict control of foodstuffs, and relocation of the population living in affected areas. Putting these countermeasures into practice requires spending large amounts of resources and can produce significant social and psychological effects on the affected population. Recent studies carried out in the region affected by the Chernobyl accident show that training the population to live with enhanced levels of radioactivity can help them to reduce the social and physiological effects and contribute decisively to normalizing the situ­ation. The aftermath of the Chernobyl accident shows also that the efficient implementation of adequate countermeasures in the early emergency phase can reduce some long-term health effects such as thyroid cancer produced by inhalation and ingestion through milk of radioactive iodine.