RADON EXAMS SCRIPT UPDATED STUDY QUESTIONS AND
ANSWERS GRADED A+
✔✔If a short-term, closed building radon test is conducted in the basement of a home
with a result of 10 pCi/L, what can be said about the radon levels on the first floor above
the basement? - ✔✔The first floor radon level is likely to be equal to or less than the
basement measurement of 10
✔✔If the water for a home comes from an underground well that has 60,000 pCi/L in the
water, how much radon will be added to the air of the home due to normal usage of
water? - ✔✔6 to 10 pCi/L
✔✔In a cold climate, stack effect is typically higher during the: - ✔✔Winter
✔✔In a house with a forced air heating and cooling system, which of the following
conditions would most likely increase short-term indoor radon concentrations the most?
- ✔✔Return ducts under the slab with the air blower on.
✔✔In most homes the main source of elevated radon levels is: - ✔✔the soil.
✔✔Indoor Radon levels are always higher during the winter months (November through
March) than any other time of year. - ✔✔False
✔✔On a nationwide basis, which of the following radon entry mechanisms account for
the greatest amount of radon entry? - ✔✔Convective movement of soil gas into the
building.
✔✔On an overall basis for similarly constructed homes in the same climatic area, under
which of the following conditions might one expect the highest radon entry into a home?
- ✔✔Highly permeable soil with high radium content beneath the house which is entirely
built over a crawl space.
✔✔Pipe chases up through interiors of apartment buildings can provide radon pathways
to upper level units. - ✔✔True
✔✔Temperature induced stack effect is greatest when: - ✔✔The outdoor temperatures
are very low relative to interior temperatures
✔✔The primary reason indoor radon levels are generally higher in basements is the fact
that: - ✔✔the basement is closest to the radon source.
✔✔The radon concentration of a private well for a home was determined to be 15,000
pCi/L of water. Which of the following is the most appropriate recommendation? -
,✔✔Before proceeding to reducing the radon in the water, a radon-in-air test should be
conducted.
✔✔The water supply to a home has been determined to be 9,500 pCi per liter of water.
A radon in air test was also conducted while it was occupied with a result of 22 pCi/L of
radon in the air. What is the predominant source of radon? - ✔✔From the soil
✔✔What is one of the main differences between testing for radon in schools versus
testing in single family homes? - ✔✔More robust forced air systems can cause
significant differences from one room to another in a school
✔✔What is the neutral pressure plane within a home? - ✔✔It is the general location
within the home, above which the house is at positive pressure relative to the outdoors
and below which the house is at negative pressure relative to the outdoors.
✔✔What is the typical effect that the addition of outdoor air has on indoor radon levels?
- ✔✔It typically reduces indoor radon
✔✔When is fresh air typically provided to large buildings such as schools? - ✔✔During
occupied hours
✔✔Which of the following mechanical ventilation systems or conditions would most
likely reduce radon entry? - ✔✔Evaporative cooler
✔✔Which of the following situations is caused by wind blowing on a home built on a
hillside? - ✔✔Soil pressurization and increased radon entry.
✔✔Which of the following variables is the best predictor of potential radon
concentrations in buildings? - ✔✔Radium content in the soil.
✔✔Short-term tests conducted in the same location with the house being under closed
building conditions will not vary more than 10 percent when tests are conducted at
different times of the year. - ✔✔False
✔✔A curie is defined as: - ✔✔the radioactivity of one gram of radium.
✔✔A house was tested for radon and radon decay progeny. The results were 10 pCi/L
and 0.08 WL. What would most likely account for these measurements? - ✔✔The
ventilation rate is very low and has high particulate count in air.
ER = WL X 100 / Rn
ER = 0.08 X
ER = 8/10 = 0.8 or 80%
, This is higher than the typically assumed 50%, which means there are more decay
products in the air than is typical. This would be caused by stagnant air or lots of
particulates in the air.
✔✔A measurement of 2 WL is made in a home. Using typical equilibrium ratio
assumptions, the radon concentration is: - ✔✔400 pCi/L
✔✔A measurement of 4 pCi/L is made in a home. Using typical equilibrium ratio
assumptions, the working level is: - ✔✔0.02 WL
Use the equilibrium equation to solve for radon decay products in units of working levels
(WL). Assume 50% ER since no additional information was provided.
WL = ER X Rn / 100
WL = .5 X
WL =
WL = 0.02 WL
✔✔A radioactive element, which has a half-life of 30 days, was collected in a sealed
container. If on January 1 it was determined that the container held 100 grams of this
specific element, how much of this same specific material would be in the container as
of June 1 of the same year? - ✔✔3.13 grams
Be careful and make sure you determine the number of half life intervals. You might
assume January to June is 6 months -- and since the half life is a month -- 6 half lives
have transpired. But it is only 5 months since stopped on June 1 rather than June 30.
Jan 1 - 100 grams
Feb 1 - 50 grams
Mar 1 - 25 grams
Apr 1 - 12.5 grams
May 1 - 6.25 grams
Jun 1 - 3.13 grams
✔✔An equilibrium ratio of 50 percent is typically assumed in residential buildings. What
does this mean? - ✔✔Of the radon decay products that were produced from the radon
in the room, only half of them are floating around in the air space and available for
breathing or measurement.
✔✔An ion is: - ✔✔An atom that has either gained or lost an electron
✔✔Assuming an equilibrium ratio of 0.5 (50%), 4 pCi/L equates to how many working
levels? - ✔✔0.2
Using the pie chart described within the course, we can solve for radon decay products
or WL if we assume an equilibrium factor. When assuming, we will use 50%.
ANSWERS GRADED A+
✔✔If a short-term, closed building radon test is conducted in the basement of a home
with a result of 10 pCi/L, what can be said about the radon levels on the first floor above
the basement? - ✔✔The first floor radon level is likely to be equal to or less than the
basement measurement of 10
✔✔If the water for a home comes from an underground well that has 60,000 pCi/L in the
water, how much radon will be added to the air of the home due to normal usage of
water? - ✔✔6 to 10 pCi/L
✔✔In a cold climate, stack effect is typically higher during the: - ✔✔Winter
✔✔In a house with a forced air heating and cooling system, which of the following
conditions would most likely increase short-term indoor radon concentrations the most?
- ✔✔Return ducts under the slab with the air blower on.
✔✔In most homes the main source of elevated radon levels is: - ✔✔the soil.
✔✔Indoor Radon levels are always higher during the winter months (November through
March) than any other time of year. - ✔✔False
✔✔On a nationwide basis, which of the following radon entry mechanisms account for
the greatest amount of radon entry? - ✔✔Convective movement of soil gas into the
building.
✔✔On an overall basis for similarly constructed homes in the same climatic area, under
which of the following conditions might one expect the highest radon entry into a home?
- ✔✔Highly permeable soil with high radium content beneath the house which is entirely
built over a crawl space.
✔✔Pipe chases up through interiors of apartment buildings can provide radon pathways
to upper level units. - ✔✔True
✔✔Temperature induced stack effect is greatest when: - ✔✔The outdoor temperatures
are very low relative to interior temperatures
✔✔The primary reason indoor radon levels are generally higher in basements is the fact
that: - ✔✔the basement is closest to the radon source.
✔✔The radon concentration of a private well for a home was determined to be 15,000
pCi/L of water. Which of the following is the most appropriate recommendation? -
,✔✔Before proceeding to reducing the radon in the water, a radon-in-air test should be
conducted.
✔✔The water supply to a home has been determined to be 9,500 pCi per liter of water.
A radon in air test was also conducted while it was occupied with a result of 22 pCi/L of
radon in the air. What is the predominant source of radon? - ✔✔From the soil
✔✔What is one of the main differences between testing for radon in schools versus
testing in single family homes? - ✔✔More robust forced air systems can cause
significant differences from one room to another in a school
✔✔What is the neutral pressure plane within a home? - ✔✔It is the general location
within the home, above which the house is at positive pressure relative to the outdoors
and below which the house is at negative pressure relative to the outdoors.
✔✔What is the typical effect that the addition of outdoor air has on indoor radon levels?
- ✔✔It typically reduces indoor radon
✔✔When is fresh air typically provided to large buildings such as schools? - ✔✔During
occupied hours
✔✔Which of the following mechanical ventilation systems or conditions would most
likely reduce radon entry? - ✔✔Evaporative cooler
✔✔Which of the following situations is caused by wind blowing on a home built on a
hillside? - ✔✔Soil pressurization and increased radon entry.
✔✔Which of the following variables is the best predictor of potential radon
concentrations in buildings? - ✔✔Radium content in the soil.
✔✔Short-term tests conducted in the same location with the house being under closed
building conditions will not vary more than 10 percent when tests are conducted at
different times of the year. - ✔✔False
✔✔A curie is defined as: - ✔✔the radioactivity of one gram of radium.
✔✔A house was tested for radon and radon decay progeny. The results were 10 pCi/L
and 0.08 WL. What would most likely account for these measurements? - ✔✔The
ventilation rate is very low and has high particulate count in air.
ER = WL X 100 / Rn
ER = 0.08 X
ER = 8/10 = 0.8 or 80%
, This is higher than the typically assumed 50%, which means there are more decay
products in the air than is typical. This would be caused by stagnant air or lots of
particulates in the air.
✔✔A measurement of 2 WL is made in a home. Using typical equilibrium ratio
assumptions, the radon concentration is: - ✔✔400 pCi/L
✔✔A measurement of 4 pCi/L is made in a home. Using typical equilibrium ratio
assumptions, the working level is: - ✔✔0.02 WL
Use the equilibrium equation to solve for radon decay products in units of working levels
(WL). Assume 50% ER since no additional information was provided.
WL = ER X Rn / 100
WL = .5 X
WL =
WL = 0.02 WL
✔✔A radioactive element, which has a half-life of 30 days, was collected in a sealed
container. If on January 1 it was determined that the container held 100 grams of this
specific element, how much of this same specific material would be in the container as
of June 1 of the same year? - ✔✔3.13 grams
Be careful and make sure you determine the number of half life intervals. You might
assume January to June is 6 months -- and since the half life is a month -- 6 half lives
have transpired. But it is only 5 months since stopped on June 1 rather than June 30.
Jan 1 - 100 grams
Feb 1 - 50 grams
Mar 1 - 25 grams
Apr 1 - 12.5 grams
May 1 - 6.25 grams
Jun 1 - 3.13 grams
✔✔An equilibrium ratio of 50 percent is typically assumed in residential buildings. What
does this mean? - ✔✔Of the radon decay products that were produced from the radon
in the room, only half of them are floating around in the air space and available for
breathing or measurement.
✔✔An ion is: - ✔✔An atom that has either gained or lost an electron
✔✔Assuming an equilibrium ratio of 0.5 (50%), 4 pCi/L equates to how many working
levels? - ✔✔0.2
Using the pie chart described within the course, we can solve for radon decay products
or WL if we assume an equilibrium factor. When assuming, we will use 50%.
