What’s the Difference Between Alpha, Beta and Gamma Radiation?
Everything in nature would prefer to be in a relaxed, or stable state. Unstable atoms undergo nuclear processes that cause them to become more stable. One such process involves emitting excess energy from the nucleus. This process is called radioactivity or radioactive decay. “Radiation” and “radioactivity” are often confused, the proper relationship is that “radioactive atoms emit radiation.”
The three main types of nuclear radiation emitted from radioactive atoms and included in all nuclear fallout are:
Alpha: These are actual particles that are electrically charged and are commonly referred to as alpha particles. Alpha particles are the least penetrating of the three primary forms of radiation, as they cannot travel more than four to seven inches in air and a single sheet of paper or the outermost layer of dead skin that covers the body will stop them. However, if alpha particle emitting radioactive material is inhaled or ingested, they can be a very damaging source of radiation with their short range being concentrated internally in a very localized area.
Beta: These are also actual particles that are electrically charged and are commonly referred to as beta particles. Beta particles travel faster and penetrate further than alpha particles. They can travel from a few millimeters up to about ten yards in open air depending on the particular isotope and they can penetrate several millimeters through tissue. Beta particle radiation is generally a slight external exposure hazard, although prolonged exposure to large amounts can cause skin burns and it is also a major hazard when interacting with the lens of the eye. However, like alpha particles, the greatest threat is if beta particle emitting radioactive material is inhaled or ingested as it can also do grave internal damage.
Gamma: Gamma rays are similar to x-rays, they are a form of electromagnetic radiation. Gamma rays are the most hazardous type of external radiation as they can travel up to a mile in open air and penetrate all types of materials. Since gamma rays penetrate more deeply through the body than alpha or beta particles, all tissues and organs can be damaged by sources from outside of the body. Only sufficiently dense shielding and/or distance from gamma ray emitting radioactive material can provide protection.
Bottom Line: All three of the primary types of radiation above can be a hazard if emitted from radioactive nuclear fallout that was inhaled or ingested. Protected food and water and even a simple inexpensive dust protector face mask can go a long ways to denying this route of entry. However, for the penetrating gamma rays, it is essential to be able to identify the best protected shielding and distance options available.
What’s the Difference Between Roentgen, Rad and Rem Radiation Measurements?
Since nuclear radiation affects people, we must be able to measure its presence. We also need to relate the amount of radiation received by the body to its physiological effects. Two terms used to relate the amount of radiation received by the body are exposure and dose. When you are exposed to radiation, your body absorbs a dose of radiation.
As in most measurement quantities, certain units are used to properly express the measurement. For radiation measurements they are…
Roentgen: The roentgen measures the energy produced by gamma radiation in a cubic centimeter of air. It is usually abbreviated with the capital letter “R”. A milliroentgen, or “mR”, is equal to one one-thousandth of a roentgen. An exposure of 50 roentgens would be written “50 R”.
Rad: Or, Radiation Absorbed Dose recognizes that different materials that receive the same exposure may not absorb the same amount of energy. A rad measures the amount of radiation energy transferred to some mass of material, typically humans. One roentgen of gamma radiation exposure results in about one rad of absorbed dose.
Rem: Or, Roentgen Equivalent Man is a unit that relates the dose of any radiation to the biological effect of that dose. To relate the absorbed dose of specific types of radiation to their biological effect, a “quality factor” must be multiplied by the dose in rad, which then shows the dose in rems. For gamma rays and beta particles, 1 rad of exposure results in 1 rem of dose.
Other measurement terms: Standard International (SI) units which may be used in place of the rem and the rad are the sievert (Sv) and the gray (Gy). These units are related as follows: 1Sv = 100 rem, 1Gy = 100 rad. Two other terms which refer to the rate of radioactive decay of a radioactive material are curie (Ci) and becquerel (Bq).
Bottom Line: Fortunately, cutting through the above confusion, for purposes of practical radiation protection in humans, most experts agree (including FEMA Emergency Management Institute) that Roentgen, Rad and Rem can all be considered equivalent. The exposure rates and doses you’ll usually see will be expressed simply in terms of roentgen (R) or milliroentgen (mR). Remember, too, a milliroentgen, or “mR”, is equal to one one-thousandth of a roentgen “R”.
How Much Radiation Is Too Much?
Expected health effects for an adult assuming the cumulative total radiation exposure was all received within a weeks time.
For children, the effects can be expected at half these dose levels.
TOTAL EXPOSURE ONSET & DURATION OF INITIAL SYMPTOMS & DISPOSITION
30 to 70 R From 6-12 hours: none to slight incidence of transient headache and nausea;
vomiting in up to 5 percent of personnel in upper part of dose range. Mild
lymphocyte depression within 24 hours. Full recovery expected. (Fetus damage
possible from 50R and above.)
70 to 150 R From 2-20 hours: transient mild nausea and vomiting in 5 to 30 percent of
personnel. Potential for delayed traumatic and surgical wound healing,
minimal clinical effect. Moderate drop in lymphocycte, platelet, and
granulocyte counts. Increased susceptibility to opportunistic pathogens.
Full recovery expected.
150 to 300 R From 2 hours to three days: transient to moderate nausea and vomiting in
20 to 70 percent; mild to moderate fatigability and weakness in 25 to 60
percent of personnel. At 3 to 5 weeks: medical care required for 10 to 50%.
At high end of range, death may occur to maximum 10%. Anticipated medical
problems include infection, bleeding, and fever. Wounding or burns will
geometrically increase morbidity and mortality.
300 to 530 R From 2 hours to three days: transient to moderate nausea and vomiting in 50
to 90 percent; mild to moderate fatigability in 50 to 90 percent of personnel.
At 2 to 5 weeks: medical care required for 10 to 80%. At low end of range,
less than 10% deaths; at high end, death may occur for more than 50%.
Anticipated medical problems include frequent diarrheal stools, anorexia,
increased fluid loss, ulceration. Increased infection susceptibility during
immunocompromised time-frame. Moderate to severe loss of lymphocytes.
Hair loss after 14 days.
530 to 830 R From 2 hours to two days: moderate to severe nausea and vomiting in 80 to
100 percent of personnel; From 2 hours to six weeks: moderate to severe
fatigability and weakness in 90 to 100 percent of personnel. At 10 days to
5 weeks: medical care required for 50 to 100%. At low end of range, death
may occur for more than 50% at six weeks. At high end, death may occur
for 99% of personnel. Anticipated medical problems include developing
pathogenic and opportunistic infections, bleeding, fever, loss of appetite,
GI ulcerations, bloody diarrhea, severe fluid and electrolyte shifts, capillary
leak, hypotension. Combined with any significant physical trauma, survival
rates will approach zero.
830 R Plus From 30 minutes to 2 days: severe nausea, vomiting, fatigability, weakness,
dizziness, and disorientation; moderate to severe fluid imbalance and headache.
Bone marrow total depletion within days. CNS symptoms are predominant at
higher radiation levels. Few, if any, survivors even with aggressive and
immediate medical attention.
The effects from the above radiation dose levels assume that the total dose was received over a short period of time of a week or less.
In a serious nuclear event, there may be no escaping some radiation most everywhere. It would be very hard then not to exceed the conservative govt agencies peace-time usual advice to try to limit your normal exposure to 5 rad per year and 25 rad for lifetime and emergency workers to 50 rad. 10 11 (Limits lower for children & fetuses.)
You always want to try to minimize any radiation exposure to ALARA or As Low As Reasonably Achievable, ideally <100 rads, as that’s still 100% survivable for healthy adults, if not exceeded. “Very few of those receiving acute doses (received within 24 hours) of less than 100 R would become sick, even briefly.”NWSS.
The response to radiation varies widely amongst people and the longer the time frame over which a specific dose is accumulated the better your body can respond to, and recover from, that radiation damage. In other words, a normally fatal (to 50% of a group exposed to it) cumulative dose of 530 R, if received all within a week or less, would create few noticeable ill health effects if it was received, but spread out over a years time at the rate of about 10 R per week. That would be less than 1.5 R per day.