atomic number materials are recommended. Also, using a material with a high neutron activation cross section to shield neutrons will result in the shielding material itself becoming radioactive and hence more dangerous than if it were not present. Personal Protective Equipment (PPE)—Radiation Personal Protection Equipment (PPE) includes all clothing and accessories which can be worn to prevent severe illness and injury as a result of exposure to radioactive material. These include an SR100 (protection for 1hr), SR200 (protection for 2 hours). Because radiation can affect humans through internal and external contamination, various protection strategies have been developed to protect humans from the harmful effects of radiation exposure from a spectrum of sources. A few of these strategies developed to shield from internal, external, and high energy radiation are outlined below. Internal Contamination Protective Equipment Internal contamination protection equipment protects against the inhalation and ingestion of radioactive material. Internal deposition of radioactive material result in direct exposure of radiation to organs and tissues inside the body. The respiratory protective equipment described below are designed to minimize the possibility of such material being inhaled or ingested as emergency workers are exposed to potentially radioactive environments. Reusable Air Purifying Respirators (APR) Elastic face piece worn over the mouth and nose Contains filters, cartridges, and canisters to provide increased protection and better filtration Powered Air-Purifying Respirator (PAPR) Battery powered blower forces contamination through air purifying filters Purified air delivered under positive pressure to face piece Supplied-Air Respirator (SAR) Compressed air delivered from a stationary source to the face piece Auxiliary Escape Respirator Protects wearer from breathing harmful gases, vapours, fumes, and dust Can be designed as an air-purifying escape respirator (APER) or a self-contained breathing apparatus (SCBA) type respirator SCBA type escape respirators have an attached source of breathing air and a hood that provides a barrier against contaminated outside air Self Contained Breathing Apparatus (SCBA) Provides very pure, dry compressed air to full facepiece mask via a hose Air is exhaled to environment Worn when entering environments immediately dangerous to life and health (IDLH) or when information is inadequate to rule out IDLH atmosphere External Contamination Protective Equipment External contamination protection equipment provides a barrier to shield radioactive material from being deposited externally on the body or clothes. The dermal protective equipment described below acts as a barrier to block radioactive material from physically touching the skin, but does not protect against externally