Shortening the time of exposure, increasing distance from a radiation source and shielding are the basic countermeasures (or protective measures) to reduce doses from external exposure.
||The less time that people are exposed to a radiation source, the less the absorbed dose.
||The farther away that people are from a radiation source, the less the absorbed dose.
||Barriers of lead, concrete or water can stop radiation or reduce radiation intensity.
To reduce doses from intake of radioactive substances, the following basic countermeasures can be considered:
shortening time of exposure to contaminants;
preventing surface contamination;
preventing inhalation of radioactive materials in air; and
preventing ingestion of contaminated foodstuffs and drinking water.