Environmental Engineering Reference
In-Depth Information
RADON RISK EVALUATION CHART
pCi/L
WL
Estimated number of
LUNG CANCER
DEATHS due to radon
exposure (out of 1000)
Comparable
exposure levels
Comparable risk
200
1
440-770
1000 times average
outdoor level
More than 60 times
non-smoker risk
4 pack-a-day
smoker
100
0.5
270-630
100 times average
indoor level
20,000 chest x-rays
per year
40
0.2
120-380
2 pack-a-day
smoker
20
0.1
60-210
100 times average
outdoor level
1 pack-a-day
smoker
10
0.05
30-120
10 times average
indoor level
5 times non-smoker
risk
4
0.02
13-50
200 chest x-rays per
year
2
0.01
7-30
10 times average
outdoor level
Non-smoker risk of
dying from lung
cancer
1
.005
3-13
Average outdoor level
20 chest x-rays per
year
0.2
.001
1-3
Average indoor level
Figure 2.11
USEPA radon risk estimate and equivalency chart. (From USEPA,
Citi-
zens Guide to Radon
, EPA 86-004, 1986.)
control technology in high radon houses, it was concluded that reductions
in radon levels below 4 pCi/L were not achievable. As a consequence, 4
pCi/L became, by default, the action level for remediation. This action level
is not based on radiation biology assessments of safety. As such, it is not a
magic number that determines whether the radon level in a particular dwell-
ing is safe or not, as many homeowners (and in some cases radon profes-
sionals) are wont to believe. Since there appears to be no threshold, no
amount of radon/RDPs indoors or outdoors is safe. Safety is a relative term.
Exposures of 4 pCi/L annual average are less safe than 2 pCi/L; measured
exposure concentrations of 4.05 and 3.9 pCi/L are not significantly different
