Radon is a significant indoor air pollutant, considered the second leading cause of lung cancer in the U.S., with about 20,000 deaths annually. The EPA recommends testing all homes for radon due to high exposure risks, particularly in areas with high soil permeability. Effective mitigation methods include active sub-slab suction and radon-resistant construction techniques to reduce health risks.

1. INDOOR AIR POLLUTION: RADON

In 1990 EPA placed indoor air pollution at the top of the list of 18
sources of cancer risk

Indoor pollution is rated by risk analysis scientists as high-risk
health problem for humans

Radon is one of the three most dangerous indoor air pollutants,
along with cigarette smoke and formaldehyde

Radon is the second leading cause of lung cancer, after smoking

Nearly 1 in 15 homes in the U.S. has high level of indoor radon

The U.S. Surgeon General and EPA recommend all homes be
tested for radon

Homes with high radon level can be fixed

2. INDOOR AIR POLLUTION: RADON
CHARACTERISTICS

Radioactive element

Naturally occurring

Colorless, odorless, and tasteless

Derived from natural decay of uranium

Chemically inert

When it decays, it releases decay products (progeny) which
can attach themselves to tiny dust particles in indoor air and
can be inhaled into human lungs, exposing them to densely
ionizing alpha particles

3. INDOOR AIR POLLUTION:RADON
Radon is estimated to
cause about 20,000
deaths per year. The
number of deaths
from other causes are
taken from the 1990
National Safety
Council Report.

4. INDOOR AIR POLLUTION:RADON

Most of the cancer risk
resulting from radon in
the household water
supply is due to
inhalation of the
radioactive by-products
that are produced from
radon that has been
released from the water
into the air, rather than
from drinking water.

5. INDOOR AIR POLLUTION: RADON

6. INDOOR AIR POLLUTION: RADON

EPA map of radon
zones, New York
State.

Zone 1, red, highest
potential (greater than
4 pCi/L)

Zone 2, orange,
moderate potential
(from 2 to 4 pCi/L)

Zone 3, yellow, low
potential (less than 2
pCi/L)

7. INDOOR AIR POLLUTION: RADON
Radon levels in outdoor
air, indoor air, soil air and
ground water can be very
different.

8. INDOOR AIR POLLUTION:RADON
Radon Formation
Each atom of radium decays
by ejecting from its nucleus an
alpha particle composed of two
neutrons and two protons. As
alpha particle is ejected, the
newly formed radon atom
recoils in the opposite
direction, just as a high-
powered rifle recoils when a
bullet is fired. Alpha recoil is
the most important factor
affecting the release of radon
from mineral grains.

9. INDOOR AIR POLLUTION: RADON
Radon can move through
crack in rocks and
through pore spaces in
soils. Radon moves more
rapidly through
permeable soils, such as
coarse sand and gravel.

10. INDOOR AIR POLLUTION: RADON
Some radon atoms
remain trapped in the
soil and decay to form
lead; other atoms
escape quickly into the
air.
Homes in areas with
drier, highly permeable
soils, may have high
levels of indoor radon.

11. INDOOR AIR POLLUTION: RADON
A. Cracks in concrete slabs
B. Spaces behind brick walls
C. Pores and cracks in concrete
blocks
D. Floor wall joints
E. Exposed soil as in a sump
F. Weeping tile, if drained to open
sump
G. Mortar joints
H. Loose fitting pipe penetrations
I. Open tops of block walls
J. Building materials such as some
rocks
K. Water, from some wells

12. INDOOR POLLUTION: RADON
In areas where the main
water supply is from
private wells and small
public water works, radon
in ground water can add
radon to the indoor air.

13. INDOOR AIR POLLUTION: RADON
HEALTH EFFECTS

Radon causes about 20,000 lung cancer deaths each year (only
effect definitely linked)

Even very small exposures to radon can result in lung cancer

No threshold below which levels are harmless

Many smokers will get lung cancer because of the synergy
between radon and cigarette smoking

Epidemiological studies (miners) an animal studies are supporting
evidence that confirm radon as a cause of lung cancer

The BEIR (“Biological Effects of Ionizing Radiation”) VI Report of
the National Academy of Sciences, the most comprehensive study
to date, supports that conclusion.

14. INDOOR AIR POLLUTION: RADON
Soil Air Radon Data
A scientist collects samples of soil air to
determine its radon content.
The methods for measuring radon can be a
passive device buried in the soil, or a sample
of soil air collected from a probe driven into the
ground.

15. INDOOR AIR POLLUTION: RADON
Methods for
measuring alpha
particles produced by
the decay of the
radon in the air.

16. INDOOR AIR POLLUTION:RADON
Active Sub slab Suction
It is the most common and
most reliable radon reduction
method. One or more suction
pipes are inserted through the
floor slab into the soil
underneath. A radon vent fan
connected to the suction pipes
draws the radon gas from
below the house and releases
it into the outdoor air while
creating a negative pressure
(vacuum) beneath the slab.

17. INDOOR AIR POLLUTION: RADON
Radon Resistant-
Construction Techniques
A. Gas Permeable Layer
B. Plastic Sheeting
C. Sealing and Caulking
D. Vent Pipe
E. Junction Box
Other radon reduction
techniques include sealing,
home/room pressurization,
heat recovery ventilation and
natural ventilation.

18. INDOOR AIR POLLUTION:RADON
Conclusions

Indoor radon is a public health problem

Millions of homes are estimated to have
elevated radon levels

The solution is straight forward

The health risks of radon can be reduced