Radiation Emergency Preparedness and Response


Radiation emergencies pose hazards for all workers in an impacted area. Workers whose job sites are at or near the site of a radiation emergency are likely to need to shelter in place or evacuate to safety. Emergency response workers—particularly law enforcement officers, firefighters, medical and rescue workers, and other first responders—may be at particularly high risk for exposure to radiation and other hazards when in or around affected areas. Employers of workers in both categories (emergency response workers and workers near the radiation source) should be prepared to respond appropriately in the minutes, hours, and days following a radiation emergency or other emergency situation.

This page provides information specifically for emergency response workers and employers. Workers and employers without emergency response or related support functions should consult the General Businesses page for information on protective actions during and following radiation emergencies.

On this page… for emergency response workers and employers:

Health and Safety Hazards during Radiation Emergencies

During and after radiation emergencies, including during response operations and evacuation or sheltering-in-place periods, workers and employers should be aware of the hazards associated with such events. Ionizing radiation may be the primary hazard. High doses of radiation, even for short durations, can cause short- and long-term health impacts. The health effects of radiation are discussed on the Background page. Other hazards to which workers may be exposed include:

  • Hazardous substances, including releases of chemical and biological agents resulting from the initial explosion, subsequent structural damage/collapse, and fires and within waste and debris.
  • Entry into confined spaces, including those requiring a permit system for entry.
  • Heavy equipment and vehicular traffic, including trucks, bulldozers, cranes, fork trucks, and other equipment that will be needed to clear roads and move rubble to enable rescue operations and to control fires.
  • Hazardous energy, including electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other energy that may be hazardous if it is unexpectedly released or discharged, or if worker contact occurs.
  • Slips, trips, and falls on uneven, unstable, weakened, broken, or collapsing/collapsed walking and working surfaces and falls from heights.
  • Fires and explosions, resulting from a nuclear blast or secondary ignition of fuel sources, such as damaged containers, pipes, or utility lines.
  • Hazards associated with response tasks, including welding/cutting, trenching, and excavation.
  • Noise exposure, including from a nuclear blast, heavy equipment, and other sources.

Employers are always required to protect workers from exposure to these and other recognized health and safety hazards. The Additional Resources page provides information from other agencies about the hazards associated with radiation emergencies and ways to protect workers from associated occupational injury and illness.

Basic Protective Actions for Radiation
Three images (from left to right) Less time spent near source: less radiation received. Greater distance from source: less radiation received. Gehind sheilding from source: less radiation received. | Photo Credit: U.S. Environmental Protection Agency
U.S. Environmental Protection Agency

Radiation doses should be kept to a level that is As Low As Reasonably Achievable (ALARA). Minimizing doses consistent with the ALARA concept can be done by:

  • Minimizing time spent in areas where radiation exposure may occur.
    • Example: Plan emergency response missions efficiently so that first responders enter and leave areas where they may be exposed or become contaminated as few times as possible, and so that they spend as little time as possible in those areas.
  • Maximizing distance between a worker and a source of radiation exposure.
    • Example: Focus response operations in areas farther from the source of radiation. This is particularly important in situations involving nuclear detonations where dangerous fallout and heavy damage may limit the number of survivable victims in areas closest to the blast zone. In general, radiation intensity decreases rapidly with distance; intensity is inversely proportional to the square of the distance from the source.
  • Using proper hazard controls, including shielding workers from a radiation source and contamination. Shielding may include the use of personal protective equipment (PPE).
    • Example: Shield your body from radiation by staying on the opposite side of a cinder block wall from a radiation source.
Dose Limits for Emergency Response Situations

Employers must comply with all applicable OSHA requirements, including worker dose limits (i.e., occupational exposure limits) for ionizing radiation during emergency response operations. OSHA's Ionizing Radiation standards set or, in some instances, incorporate by reference the requirements for protecting workers from over-exposure.

Even during emergency response operations, OSHA standards always apply. OSHA protections cover most private sector and civilian federal employees in all U.S. states and territories. Public-sector employees, including emergency responders, in states that operate their own OSHA-approved occupational safety and health programs (State Plans) are covered by state OSHA requirements.

OSHA has consistently interpreted the Ionizing Radiation standards as applying to all workplaces covered by the Occupational Safety and Health (OSH) Act of 1970, except in agriculture or workplaces exempted from OSHA jurisdiction by section 4(b)(1) of the OSH Act.

Employers should note that, during the initial emergency response to a radiation emergency, OSHA will likely operate in a technical assistance and support mode, pursuant to the National Response Framework, rather than issuing citations for workplace violations. However, OSHA retains its enforcement authority under the OSH Act. The guidance on this webpage assumes that hazards associated with a radiation emergency, including ionizing radiation, are likely to be extreme compared to those associated with non-emergency conditions. Employers may not be able to control extreme hazards to the degree ordinarily required by the OSH Act and OSHA standards.

For workers engaged in response operations covered by OSHA's ionizing radiation standards for general industry (29 CFR 1910.1096)—including in shipyard employment, marine terminals, and longshoring where the general industry standard applies—and construction (29 CFR 1926.53), dose limits, including to certain parts of the body from external exposures, are described by Table G-18 of the general industry standard:

  Rem per calendar quarter
Whole body: Head and trunk; active blood-forming organs; lens of eyes; or gonads 1 1/4
Hands and forearms; feet and ankles 18 3/4
Skin of whole body 7 1/2

The Ionizing Radiation standards generally limit whole-body occupational ionizing radiation dose to 1.25 rem per calendar quarter. Responders generally must not exceed a 5-rem (0.05 Sv) annual whole-body dose of ionizing radiation.1 However, this webpage does not provide a maximum exposure dose (i.e., turnback level). It is not possible to predict for extreme events all of the factors that would be necessary to establish a single maximum dose that could apply to all responders for all missions. The 5, 10, and 25 rem (0.05, 0.1, and 0.25 Sv) guidelines described in the table below should be viewed as flexible limits applicable to the range of early phase emergency response actions. They should serve as decision points for planning for the protection of responders during response to a nuclear detonation. Incident Commanders need to understand and consider the risks associated with various doses of ionizing radiation, and establish protocols as part of the planning process for determining when to stop, or not initiate, actions.

In any situation where responders may be exposed to ionizing radiation, employers or incident commanders must take all reasonable actions to minimize dose and provide appropriate protection to responders. The Incident Commander or employer must ensure that responders are adequately informed of and have an adequate understanding of the risks associated with the actions to be taken and are appropriately trained on those actions. The National Council on Radiation Protection and Measurements (NCRP) Commentary 19 – Key Elements of Preparing Emergency Responders for Nuclear and Radiological Terrorism, Appendix A*, provides guidance on essential training competencies for varying levels of emergency responders responding to nuclear emergencies. NCRP also provides an overview of this commentary.

Since there is assumed to be no risk-free radiation dose (i.e., a threshold below which there is not an associated risk), responders who are reasonably expected to receive more than 25 percent of the occupational dose limit should be appropriately trained and monitored. See the Ionizing Radiation standards.

The table below provides recommended guidelines for emergency worker exposure during the early phase of a response to a catastrophic radiation emergency, such as a nuclear detonation. It is important to note that these limits are only considered for use during the early phase of a response and that stricter controls are established during the longer-term intermediate and late phases associated with recovery. In these later phases, standard worker protections, including the 1.25-rem/quarter (0.0125-Sv) occupational dose limit, normally apply. In all cases, reasonably achievable actions should be taken to minimize doses (i.e., maintain doses ALARA). If workers may receive doses higher than 5 rem during the course of the response, there are several conditions that should be met, as outlined in the table, below:

Emergency worker guidelines in the early phase of a catastrophic radiation emergency response

Note that the table is intended to provide information for use during a catastrophic radiation emergency, such as a nuclear detonation. Employers and incident commanders should not allow workers to receive such high doses in more controlled response operations, such as those involving smaller radiological sources.

Activity Total Effective Dose Equivalent (TEDE)a Guideline Conditions
For all exposures, responders must be fully informed of the risks of exposure they may experience and must be trained on protective actions to be taken. Each responder should make an informed decision as to how much radiation risk he/she is willing to accept to save lives.
Annual limit for all occupational exposures, including for radiation workersb 5 rem
(0.05 Sv)
  • All reasonably achievable actions must be taken to minimize dose.
Infrastructure protection and restoration necessary for public welfare (e.g., a power plant), in lower-hazard areas such as the Light Damage zone and fallout areas around a nuclear detonation site, excluding the Dangerous Fallout zone and elevated radiation areas 10 rem
(0.10 Sv)
  • All appropriate actions and controls must be implemented; however, exceeding 5 rem (0.05 Sv) is unavoidable.
  • Appropriate respiratory protection and other personal protection is provided and used.
  • Monitoring available to project or measure dose.
Life-saving, medical response, infrastructure restoration, or protection of populations in medium-hazard areas, such as the Moderate Damage zone around a nuclear detonation site, and fallout areas excluding the Dangerous Fallout zone 25 rem
(0.25 Sv)
  • All appropriate actions and controls must be implemented; however, exceeding 5 rem (0.05 Sv) is unavoidable.
  • Appropriate respiratory protection and other personal protection is provided and used.
  • Monitoring available to project or measure dose.
Life-saving and critical infrastructure missions (i.e., missions that directly protect significant populations from substantial risks of injury, illness, or death) in high-hazard zones, including the Dangerous Fallout zone, to include missions that critically enable the larger response effort, such as fire suppression and critical infrastructure engineering missions Greater than 25 remc
(> 0.25 Sv)
  • All appropriate actions and controls must be implemented; however, exceeding 5 rem (0.05 Sv) is unavoidable.
  • If lifesaving emergency responder doses approach or exceed 50 rem (0.5 Sv) emergency responders must be made fully aware of both the acute and the chronic (cancer) risks of such exposure.
  • Appropriate respiratory protection and other personal protection is provided and used.
  • Monitoring available to project or measure dose.
  • Life-saving and critical infrastructure engineering missions are least likely to be successful in the Severe Damage zone; and may subject responders to lethal doses of radiation.
  • All missions are evaluated and justified by the Incident Commander, including assessment of hazards, value of the mission, and likelihood of success.

Adapted from "Health and Safety Planning Guide for Planners, Safety Officers and Supervisors for Protecting Responders Following a Nuclear Detonation" (Interagency document, 2016).

  1. The sum of the effective dose equivalent from external radiation exposure and committed effective dose equivalent from internal radiation exposure.
  2. Includes workers in Department of Energy and Nuclear Regulatory Commission-licensed facilities.
  3. The 2008 DHS Guidance and 2013 PAG Manual provide radiation emergency worker guidance, stating, “The emergency intervention needed to prevent further destruction and loss of life may result in increased exposure. Exceeding the Response Worker Guidelines … may be unavoidable in responding to such events.” Additionally the 2013 PAG Manual states, “The 25 rem (0.25 Sv) lifesaving response worker guidelines provide assurance that exposures will not result in detrimental deterministic health effects (i.e., prompt or acute effects). However, it could increase the risk of stochastic (chronic) effects, such as the risk of cancer.”

Note that dose limit guidelines in the table represent Total Effective Dose Equivalent (TEDE), the projected, total, whole-body dose from both external radiation exposure and internal radiation exposure following ingestion, inhalation, or uptake through the skin or a wound. In technical terms, TEDE is defined as the projected sum of the effective dose equivalent from external radiation exposure and Committed Effective Dose Equivalent (CEDE) from internal radiation exposure.

OSHA's Ionizing Radiation standards do not use effective dose, which, in a situation in which multiple body parts are simultaneously exposed, allows for an accounting of the separate contributions to the total risk from each exposed body part. See the definition of "dose" in paragraph (a)(5) of the general industry standard (29 CFR 1910.1096), which reflects the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the body. Issued in 1971, OSHA's standards are based on the International Commission on Radiological Protection (ICRP) Publication No. 2 – Permissible Dose for Internal Radiation. The OSHA standards set maximum allowable doses by limiting the dose to the most critically exposed body part, including the whole body, skin of the whole body, hands and forearms, and feet and ankles. They use maximum permissible concentrations (MPCs) of radionuclides, the limits for which are specified in the 1969 version of Table II of appendix B to 10 CFR part 20. Case law supports the interpretation that the original version of a referenced federal regulation is the enforceable regulation. Therefore, the 1969 version of Appendix B to 10 CFR part 20 that was referenced in the original OSHA ionizing radiation standard is enforceable.

OSHA standards and the agency's dose limits are often compared to more updated requirements of the U.S. Department of Energy (DOE) (10 CFR part 835), for workers in its facilities, and the U.S. Nuclear Regulation Commission (NRC) (10 CFR part 20), for workers in the facilities it or its agreement states license. DOE standards are based on ICRP Publication 60. Current NRC regulations are based on ICRP Publication 26 and Publication 30. Many requirements of the current NRC regulation provide as much or more protection than the OSHA standard for workers exposed to airborne radioactive materials. OSHA has issued a letter of interpretation explaining that it would be considered a de minimis condition if an employer complied with the more current regulation at 10 CFR Part 20 because the more current standard generally is considered as protective as or more protective than the older OSHA standard. There may be an unusual exposure scenario, however, in which NRC's derived airborne concentration (DAC)-based limit is less restrictive than OSHA's older MPC-based limit, such as for I-134 (S).2 OSHA determines a de minimis condition on a case-by-case basis.

Employers should also note that OSHA's dose limits are not different for pregnant workers compared to other workers. However, NCRP, ICRP, and the Conference of Radiation Control Program Directors (CRCPD) have each recommended lower doses for the fetus of workers exposed to radiation:

  • NCRP: Recommends a limit of radiation exposure for the fetus of an occupationally exposed individual of 50 millirems (mrem) (0.5 mSv) per month during the gestation period. (Report No. 116*.)
  • ICRP: Recommends a limit of radiation exposure to a member of the general public as 100 mrem (1 mSv) per year and the limit for the fetus of an occupationally exposed individual to 200 mrem (2 mSv) during the gestation period. (Publication 60.)
  • CRCPD: Suggests that the limit on exposure to the fetus of an occupationally exposed worker be kept below 500 mrem (5 mSv) during the gestation period. (Part D.)

Additionally, the NRC requires licensees to maintain exposure to the fetus of an occupationally exposed individual to 500 mrem (5 mSv) or less during the gestation period. The Pregnant Workers page of OSHA's Ionizing Radiation Safety and Health Topics page provides more information.

Emergency response workers who are pregnant may wish to discuss any possible radiation exposure resulting from their work tasks with their employer or Incident Commander and request re-assignment to a position without radiation exposure. Employers should consider reassigning workers known to be pregnant (i.e., declared pregnant workers) to job duties that minimize the radiation exposure to the worker and fetus or providing the worker with additional dose monitoring to help protect the fetus. The Centers for Disease Control and Prevention (CDC) identifies a practical threshold for birth defects in the human embryo or fetus between 10 and 20 rads (0.10–0.20 Gy). Discussing risks of radiation exposure during pregnancy with a healthcare provider in advance and having a plan in place before an incident happens (e.g., for the duration of the pregnancy) may allow the greatest flexibility in reducing worker and fetal dose.

During emergency response operations, it may not be feasible to establish controls to keep all workers' doses below the OSHA limit. Several interagency resources offer employers and other decision-makers guidance on dose limits based on extraordinary response activities:

Occupational dose limits during radiation emergencies should also reflect the stage of the response. The early phase (or emergency phase) is the period of a few hours to a few days at the beginning of the incident when immediate decisions for effective protective actions are required. Priority missions include lifesaving and first aid actions. Generally, early phase protective actions should be taken very quickly, and the protective action decisions can be modified later as more information becomes available about the type and level of radiation exposure hazards workers may face. EPA's Protective Action Guides (PAG) and Planning Guidance for Radiological Incidents (2017 PAG Manual) provides more information and recommendations at the various stages of emergency response activities.

Dose Monitoring

It is important to conduct a hazard assessment for workers conducting emergency response operations, and monitor workers' radiation doses. Detecting a radiation dose rate (radiation dose received over some amount of time) of 10 milliroentgens (mR) per hour (mR/h, or approximately 0.0001 Gy/h) may help employers and workers identify the boundaries of areas with radiation levels of concern.3


In areas where there is radiation (i.e., above background), response workers should be equipped with appropriate radiation monitoring equipment. If possible, use equipment that provides unambiguous alarms based on predefined levels (i.e., turn-back doses set by an Incident Commander, ideally well below OSHA dose limits and that indicate when workers should leave an area where they are exposed to certain levels of radiation). Workers should be trained on the specific actions to take during an instrument alarm.

Although there are several types of dosimeters, only alarming electronic dosimeters meet the above criteria.

Since it is assumed that there is no radiation dose threshold below which there is no associated risk from radiation, responders who are reasonably expected to receive more than 25 percent of the occupational dose limit should be appropriately trained and monitored. See paragraph (d) of the Ionizing Radiation standard for general industry (29 CFR 1910.1096).

Personal Protective Equipment

PPE is equipment worn to minimize exposure to hazards that other workplace controls, including engineering controls, administrative controls, and safe work practices, cannot control. During a radiation emergency, PPE will not protect workers against most types of direct, external radiation exposure. However, correctly using proper PPE will help prevent or minimize any internal exposures by preventing ingestion, inhalation, or skin absorption of radioactive materials. Radiation doses discussed in the Dose Limits for Emergency Response section, above, would then be made up mostly of direct, external radiation exposure—in the way that an X-ray causes radiation exposure. Direct external exposure can be a persistent hazard during radiation emergencies. Typically, the type of PPE required and guidelines for use are based on contamination levels.

Depending on the nature of the response operations that a particular worker is performing, the worker may need different types of PPE to protect against hazards other than radiation contamination. OSHA requires employers to select and provide appropriate PPE for their workers and ensure its proper use. Where workers provide their own protective equipment, employers are still responsible for ensuring its adequacy, proper maintenance, and decontamination.

The Preparedness page and the Getting Started – PPE for Emergency Response and Recovery Workers page discuss PPE selection, use, fit-testing, and training in detail.

Removing outer clothing and showering or, at a minimum, washing the face, hands, and any other exposed skin are essential decontamination steps.
U.S. Department of Health and Human Services (HHS), Centers for Disease Control and Prevention (CDC)

Getting radioactive material off the body as soon as possible can lower a worker's radiation dose from external contamination. Removing outer clothing and showering or, at a minimum, washing the face, hands, and any other exposed skin are essential decontamination steps. Incident commanders may also implement worker decontamination (or “decon”) procedures that include decon lines for responders exiting contaminated areas.

Decontamination of emergency response workers, their clothing, and any equipment, including PPE they may be using, is essential to limit radiation dose and prevent the spread of radioactive contamination outside of the response area. Employers whose workers may be contaminated should establish procedures for radiological monitoring or surveying workers to identify which, if any, are contaminated, and, if possible, to what extent.

If workers need to be decontaminated, employers should establish on-scene decontamination facilities with the ability to:

  • Provide an area for workers to remove contaminated clothing.
  • Provide showers for each contaminated worker to shampoo hair, wash skin, and put on clean clothes.
  • Store contaminated waste (including worker clothing and equipment) at a safe distance from people and animals.

Employers should refer to interagency resources that provide guidance on decontamination procedures, including:

The CDC provides guidance on self-decontamination after a radiation emergency that may be useful to response workers. Employers are ultimately responsible for ensuring that proper, safe decontamination practices are implemented for emergency response workers.

Medical Surveillance

OSHA's Hazardous Waste Operations and Emergency Response (HAZWOPER) standards require that employers make medical exams available to covered workers (i.e., emergency response workers) at a reasonable time and place prior to employment, periodically (at least once every 12 months), and at the termination of employment or reassignment to a non-covered position. Workers covered by this provision include:

  • Workers who are or may be exposed to hazardous substances or health hazards at or above the established permissible exposure limit, above the published exposure levels for these substances, without regard to the use of respirators, for 30 days or more a year.
  • All employees who wear a respirator for 30 days or more a year or as required by OSHA's Respiratory Protection standards.
  • All employees who are injured, become ill, or develop signs or symptoms due to possible over-exposure involving hazardous substances or health hazards from an emergency response or hazardous waste operation.
  • Members of HAZMAT teams.

The table below provides more details about specific medical surveillance provisions for workers covered by the HAZWOPER standard for general industry (29 CFR 1910.120). Employers may also be required to comply with medical surveillance provisions of the HAZWOPER standard for construction (29 CFR 1926.65) or of other OSHA standards. Employers and workers may refer to the OSHA resources tab of this web page for links to more relevant standards, standard interpretations and enforcement directives.

Medical surveillance provisions in HAZWOPER Standard (29 CFR 1910.120(f))

Note: This table does not preempt the regulatory text of 29 CFR 1910.120(f) and is provided as guidance only.

Provision Required?
Pre-placement exam Yes
Periodic exam Yes – annually or at physician's discretion
Emergency/exposure examination and tests Yes
Termination exam Yes – if no exam within 6 months of termination/reassignment
Examination includes special emphasis on these body systems Determined by physician; see standard, Appendix D, reference 10 for guidelines
Work and medical history Yes – with emphasis on symptoms related to handling hazardous substances and health hazards, fitness for duty, and ability to wear PPE
Chest x-ray No – unless determined by physician
Pulmonary function test (PFT) No – unless determined by physician
Other required tests No – unless determined by physician
Evaluation of ability to wear a respirator Yes
Additional tests as deemed necessary Yes
Written medical opinion Yes – physician to employer; employer to employee
Employee counseling regarding exam results, conditions of increased risk Yes – by physician
Medical removal plan No

Adapted from "Screening and Surveillance: A guide to OSHA Standards" (U.S. Department of Labor (DOL), Occupational Safety and Health Administration (OSHA), Publication No. OSHA-3162-12R, 2009).

Medical Management of Radiation Emergency Victims

This section provides basic information on medical management of radiation emergency victims, including emergency response workers who may become victims following radiation exposure or as a result of other hazards. This section is not meant to be a comprehensive guide for medical management of radiation victims, as it does not cover a number of important elements of this topic (e.g., bioassay, whole body counting, dose reconstruction, cytogenetic biodosimetry, dose ranges for effective countermeasures, doses of countermeasures to be administered, etc.). Other tools provide comprehensive guidance, including:

  • The U.S. Department of Health and Human Services (HHS), National Library of Medicine (NLM) Radiation Emergency Medical Management (REMM) website, which includes an interactive tool for healthcare providers to assess the clinical severity of each sub syndrome, and offers suggested treatments as well as a Response Category (RC) pertaining to guidelines for ambulatory monitoring, routine hospital care on a medical/surgical floor or care in a hospital critical care unit.
  • The U.S. Department of Energy (DOE) Oak Ridge Institute for Science and Education guidance for radiation incident management. The guidelines offer healthcare providers specific guidance on initial diagnosis (based on exposure history, symptoms, and clinical laboratory tests) and treatment of radiation exposures.

Treatment of deterministic health effects from exposure to radiation and other hazards associated with radiation emergencies should be provided by trained healthcare professionals. However, it may be dangerous or impossible to seek or reach medical care in the immediate time period following a radiation emergency event. It is therefore essential to treat non-radiation related cuts, bruises, or injuries with first aid. Unless there is a life-threatening situation, people should not leave their building or place of shelter until emergency response officials say it is safe to do so.

In the immediate minutes, hours, and days following exposure to radiation, healthcare providers should monitor victims for signs and symptoms of acute radiation syndrome or sickness (ARS). Emergency response workers and employers should watch for signs and symptoms of ARS, as described below, in themselves and others. Report any indications of ARS to their team leader, supervisor, or other appropriate personnel.

As described in the Health Effects of Radiation Exposure section of the Background page, ARS is characterized by four distinct phases:

  • A prodromal period during which victims may experience loss of appetite, nausea, vomiting, fatigue, and diarrhea; after extremely high doses, additional symptoms such as fever, prostration (laying down), respiratory distress, and hyper-excitability can occur. In cases where the dose is not sufficient to cause rapid death, these symptoms usually disappear within 1-2 days.
  • A symptom-free, latent period follows. It can vary in length depending upon the effective radiation dose.
  • Following the latent period, a period of overt illness manifests as infection (due to immune cell death and system vulnerability), electrolyte imbalance, diarrhea, bleeding, cardiovascular collapse, and, sometimes, short periods of unconsciousness. The specific symptoms will vary depending on the actual dose of radiation received (see subsyndromes).
  • Death or a period of recovery follows the period of overt illness.

ARS is also associated with four subsyndromes manifesting over a period of hours to weeks:

  • Hematopoietic subsyndrome is characterized by deficiencies of white blood cells and platelets, immune system impairment, infectious complications, bleeding, anemia, and impaired wound healing.
  • Cutaneous subsyndrome is characterized by progressively worsening skin reactions, depending on radiation dose. Skin symptoms include redness, itching, swelling, blistering, radiation burns, ulcers, and hair loss.
  • Gastrointestinal subsyndrome is characterized by loss of cells lining the gastrointestinal tract that can lead to vomiting, diarrhea, fluid loss, abdominal pain, bleeding, and infections (death of part of the intestine when its blood supply is cut off).
  • Neurovascular subsyndrome is also characterized by vomiting and diarrhea, which can occur within minutes of exposure. Other symptoms include confusion, disorientation, cerebral edema (brain swelling), drop in blood pressure, and elevated body temperature. Death may quickly follow.

Although radiation can cause local injury (e.g., to the hands and arms), whole body exposure is more likely in the event of an incident involving a nuclear detonation or improvised nuclear device (IND), radiological dispersal device(RDD),radiation exposure device (RED), or other emergency described on this page. While ARS typically would be expected at absorbed doses around 70 rad (0.7 Gy), mild symptoms may be observed with doses as low as 30 rad (0.3 Gy).4 Doses ≥100 rad (≥1 Gy) are also the doses at which elevated risk of acute death becomes a concern. At these and lower doses, signs and symptoms of ARS may be non-specific and difficult to differentiate from other illnesses and injuries, particularly in situations where there is a delay in the discovery of radiation exposure.

The table below also describes effects of whole-body irradiation, including those consistent with ARS.

Effects of Whole-Body Irradiation From External Radiation or Internal Absorption

Phase Symptom Whole-body absorbed dose, in rad (Gy)
100-200 rad (1–2 Gy) 200-600 rad
(2–6 Gy)
600-800 rad
(6–8 Gy)
800-3,000 rad
(8–30 Gy)
>3,000 rad
(>30 Gy)


Nausea and vomiting 5–50% 50–100% 75–100% 90–100% 100%
Time of onset 2–6 h 1–2 h 10–60 min < 10 min Minutes
Duration < 24 h 24–48 h < 48 h < 48 h N/A (patients die in < 48 h)
Diarrhea None None to mild (< 10%) Heavy (> 10%) Heavy (> 95%) Heavy (100%)
Time of onset 3–8 h 1–3 h < 1 h < 1 h
Headache Slight Mild to moderate (50%) Moderate (80%) Severe (80–90%) Severe (100%)
Time of onset 4–24 h 3–4 h 1–2 h < 1 h
Fever None Moderate increase (10-100%) Moderate to severe (100%) Severe (100%) Severe (100%)
Time of onset 1–3 h < 1 h < 1 h < 1 h
Central nervous system function No impairment Cognitive impairment 6–20 h Cognitive impairment > 24 h Rapid incapacitation Seizures, tremor, ataxia, lethargy
Latent period   28–31 days 7–28 days < 7 days none none
Illness   Mild to moderate leukopenia,
Moderate to severe leukopenia,
epilation (hair loss) after 300 rad (3 Gy)
Severe leukopenia,
high fever, diarrhea, vomiting, dizziness and disorientation,
Hypotension, electrolyte disturbance
Nausea, vomiting, severe diarrhea, high fever, electrolyte disturbance, shock N/A (patients die in < 48h)
Mortality Without care 0–5% 5–100% 95–100% 100% 100%
With care 0–5% 5–50% 50–100% 100% 100%
Death 6–8 weeks 4–6 weeks 2–4 weeks 2 days–2 weeks 1–2 days

Adapted from "Radiation Exposure and Contamination" (Merck Manuals, Merck & Co.).

There are no reliable antidotes once exposure to radiation has occurred or radioactive material has been inhaled or ingested. However, there are some chemicals that help cleanse the body of specific radioactive materials or block uptake of radionuclides within the body. Prussian blue has been proven effective for cesium-137 ingestion. Potassium iodide (KI) tablets are sometimes recommended for exposure to iodine-131 (I-131), a short-lived radioactive element produced by certain types of nuclear reactions. Chelation and sodium bicarbonate may also be used for certain radionuclides. For example, it was used following the Fukushima-Daiichi nuclear power plant release in Japan. Healthcare providers will determine how to treat symptoms and whether or not medical countermeasures (MCM) are appropriate for each patient.

Long-term health effects, if they occur, will likely develop decades after exposure.

More resources on MCM and medical management for workers exposed to radiation and other hazards are available on the Additional Resources tab of this web page.

Treatment of Injured/Ill Response Workers

Emergency response workers who sustain injuries or become ill (e.g., due to radiation exposure) should be monitored for contamination and decontaminated, if needed, in a safe manner before transportation to medical facilities. When a worker needs to be transported to a medical facility, the employer should inform the receiving facility of the worker's known or potential contamination with radioactive material.

Treatment of injured or ill (e.g., due to radiation exposure) response workers should be prioritized over decontamination of the worker if decontamination procedures (such as removal of clothing, showering, etc.) would aggravate the worker's condition. Removal of outer clothing and shoes can greatly reduce levels of external contamination. Workers whose clothing cannot be removed or whose bodies cannot be properly decontaminated can be covered with a blanket during transport to minimize the spread of radioactive material.

More resources on medical countermeasures (MCM) and medical management for workers exposed to radiation and other hazards are available on the Additional Resources tab of this web page.

OSHA Recordkeeping Requirements

As of January 1, 2015, all employers must report:

  • All work-related fatalities within 8 hours
  • All work-related inpatient hospitalizations, all amputations, and all losses of an eye within 24 hours.

Under the OSHA Recordkeeping requirements (29 CFR 1904), covered employers must prepare and maintain records of serious occupational injuries and illnesses using the OSHA 300 Log. This information is important for employers, workers, and OSHA in evaluating the safety of a workplace, understanding industry hazards, and implementing worker protections to reduce and eliminate hazards.

Employers are required to comply with all applicable recordkeeping requirements in other OSHA standards as well, including the agency's substance/hazard-specific standards, HAZWOPER standard (29 CFR 1910.120), and other programmatic standards. Some OSHA standards require employers to keep records of worker training, respirator fit tests, exposure monitoring, medical records (e.g., from medical examinations), and occupational injuries/illnesses.

Employers must also record any injuries incurred during the emergency response operations, as well as the results of onsite medical treatment or monitoring (e.g., for radiation exposure, heat stress, or other hazards).

Accurate and readily available records will enable an incident commander to assign workers to response and recovery activities based on their level of training, medical clearance for use of respiratory protection devices, and other factors.

Other Information

OSHA recommends these resources for more detailed information about protecting the safety and health of workers during radiation emergency response and recovery operations:

The OSHA Instruction CPL 02-00-094 – OSHA Response to Significant Events of Potentially Catastrophic Consequence describes the agency's policy for responding as quickly as possible to significant events that may affect the health or safety of employees.

More resources are available on the OSHA Resources and Additional Resources tabs of this web page.

OSHA's Role in Emergency Response and Recovery

During the response to and recovery from emergencies or disasters, OSHA helps protect the safety and health of emergency response workers. In addition to OSHA's enforcement and compliance assistance activities, OSHA can provide technical assistance and support to federal, state, local, tribal, territorial, and insular area agencies under the National Response Framework Worker Safety and Health Support Annex. The Getting Started – OSHA's Role in Emergency Response page provides additional information on this topic.

* Document or other resource available for a fee through the National Council on Radiation Protection and Measurements (NCRP), which was chartered by the U.S. Congress in 1964 to "collect, analyze, develop and disseminate in the public interest information and recommendations about protection against radiation."

1 The OSHA Ionizing Radiation standards (specifically 29 CFR 1910.1096 in general industry and, to the extent it applies, shipyard employment, marine terminals, and longshoring; and 29 CFR 1926.53 in construction) permit whole-body exposure up to 1.25 rem (0.0125 Sv) per calendar quarter, which is often applied in practice as 5 rem (0.05 Sv) per year. In circumstances where exposure above this level would not cause a worker's accumulated occupational dose to the whole body to exceed 5(n-18) rem (((5(n-18))/100) Sv), where n equals the individual's age in years at his/her last birthday, employers may permit workers to receive a 3-rem dose in a single quarter. Allowing workers to receive doses above the 1.25-rem (0.0125 Sv) quarterly limit is also contingent upon compliance with certain recordkeeping and other requirements of the Ionizing Radiation standards. Operations that fall under OSHA's Uses of Fissionable Material in Ship Repairing and Shipbuilding standard (29 CFR 1915.57) may require employers to follow different dose limits based on that standard's incorporation of Nuclear Regulatory Commission radiation protection standards (10 CFR 20).

2 Boyd, M.A. (2009). The Confusing World of Radiation Dosimetry - 9444. U.S. Environmental Protection Agency.

3 Health and Safety Planning Guide for Planners, Safety Officers and Supervisors for Protecting First Responders Following a Nuclear Detonation. Interagency document, 2016.

4 U.S. Department of Health and Human Services (HHS), Centers for Disease Control and Prevention (CDC), "Acute Radiation Syndrome: A Fact Sheet for Clinicians."