User manual

Since radon has a halflife of 3.8 days, most radon that forms
underground decomposes back into a solid, before it has a
chance to seep up out of the ground.
Radon can seep into your house through cracks and openings
in your basement or foundation, and can collect to dangerous
levels. The danger is due to the decomposition products
released by radon. These decomposition products are charged
solids, and cling to dust particles. They are highly radioac-
tive, and can lodge inside your body, when you inhale the
contaminated dust. Once lodged inside your body, they can
remain there for extended periods of time, subjecting the cells
surrounding the particles to a continuous bombardment of
ionizing radiation. This destroys and damages tissue, trigger-
ing cancers.
These same dust particles will collect on an air filter. By
running a fan forced air filter for half an hour or more, and
then placing your RM-60 as close as you can to the filter, you
can detect levels of radon gas as low as 1 picocurie per liter.
After two hours or so, the filter will reach equilibrium, that is
radon daughter products will collect as fast as they disinte-
grate, and the radiation level you detect with the RM-60 will
flatten out. From then on the radiation level will rise and fall
with the level of radon gas. You may notice the level in-
crease at night and decrease during windy weather.
The exact increase in reading due to a certain level of radon
gas depends upon the air flow rate, the efficiency of the air
filter in catching dust particles and the distance the RM-60 is
from the air filter. For example, a typical house might have
about 500,000 liters of air. If the air is contaminated with 2
picocurie of radon gas per liter, the build up of radiation on
a 99% efficient air filter, with an air flow of 1000 cubic feet
per minute, might produce an increase in reading of ap-
proximately 13 microroentgens/hr. on your RM-60, when the
average distance between the RM-60 and the filter is 1/4
meter or 52 microroentgens/hr. at 1/8 meter. Eight picocuries
of radon per liter of air might produce an increase four times
higher, or 52 or 208 microroentgens/hr. respectively. A 40%
efficient air filter could produce a reading approximately 60%
less than a 99% efficient filter. In the above example, a 40%
efficient filter might produce an increase in reading of 5.2 and
20.8 microroentgens/hr. respectively, when the air is contami-
nated with two picocurie of radon gas per liter of air. An 8
picocurie per liter air contamination could produce an increase
of approximately 21 and 84 microroentgens/hr. respectively.
Likewise a 20% efficient filter might produce an increase in
reading of 2.6 and 10.4 microroentgens/hr. respectively at two
picocurie of radon per liter and 10.5 and 42 microroentgens-
/hr. respectively at eight picocuries per liter. The above
assumes detection of gamma only. If beta and alpha are
detected as well, the increase in readings will be much higher.
EPA RECOMMENDED ACTIONS:
(Note: EPA’s action levels equate 1 picocurie Radon / liter
air with 0.005 Working Level (WL)).
The EPA recommends the following actions, when the follow-
ing various levels of radon gas contamination are found:
200 Pc/l: Take action to reduce levels, within several weeks.
If this is not possible, consult state or local health officials
about the appropriateness of relocating until the levels are
reduced.
20 to 200 Pc/l: Take action to reduce levels to below 4 Pc/l.
within several months.
4 to 20 Pc/l: Take action to reduce levels to below 4 Pc/l.
within a few years.
Less than about 4 Pc/l: Although exposure in this range does
represent some risk, reductions at these low levels are some-
times difficult to achieve.
Because of the many variables involved in detecting radon
gas, Aware Electronics suggests that if you detect any in-
crease in radiation when placing your RM-60 next to an air
filter, call your state or local health agency.
REDUCING RADON:
You can reduce a buildup of radon in your house by venting.
The most immediate method of doing this is to open basement
windows. RM-60 users have reported that background read-
ings have dropped to near normal after only several hours of
opened basement windows.
You should seal all cracks and openings, for example, around
pipes and wires that enter your basement, with a good caulk.
Urethane caulk is reported to form a good gas barrier. Latex
paint applied to cinder block or cement walls might help form
a good radon gas barrier. Floor drains and sumps are often
sources of radon. Never overlook good professional remedy
work.
CONTINUOUS RADON MONITORING:
You can continuously monitor for the return of any radon gas
by mounting the RM-60 next to the air filter in the heating or
air conditioning system or portable filter system. Use modu-
lar telephone extension cord to extend the RM-60’s cord if
need be. Set the operating parameters of the program to
average about 10 minutes per point. Set the alarm level
several microroentgens above the highest background level
you observe. For example, if the normal background level
swings between 15 and 18 microroentgens/hr, set the alarm
level to 23 microroentgens/hr. Thereafter, if radon gas begins
to build up in the house, soon after the fan in the heating, air
conditioning or portable filter system switches on, the radio-
active dust will build up on the filter, and trigger the alarm.
Portable air filter systems are available with an electrostatic
filter, charcoal filter, or good quality fiberglass filter. Place
the portable air filter, with fan in a lower part of the house,
for example in the basement. Mount the RM-60 as close as
you can to the filter. Although detection of beta emission
from radon daughters provides the highest sensitivity, the
gamma rays can be detected as well. This allows mounting
the RM-60 on the outside of the filter chamber if need be
(gamma penetrates metal).
If you foresee leaving the RM-60 in a dusty environment for
an extended period, consider placing a piece of tape over the
alpha window grid to exclude the accumulation of dust from
inside the RM-60.
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