Indoor Air Pollution: Radon

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 POLLUTIONRADON

• 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 POLLUTIONRADON

• 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 POLLUTIONRADON

• 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

1. Cracks in concrete slabs
2. Spaces behind brick walls
3. Pores and cracks in concrete blocks
4. Floor wall joints
5. Exposed soil as in a sump
6. Weeping tile, if drained to open sump
7. Mortar joints
8. Loose fitting pipe penetrations
9. Open tops of block walls
10. Building materials such as some rocks
11. 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 POLLUTIONRADON

• 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
• Gas Permeable Layer
• Plastic Sheeting
• Sealing and Caulking
• Vent Pipe
• Junction Box
• Other radon reduction techniques include
  sealing, home/room pressurization, heat recovery
  ventilation and natural ventilation.

18
INDOOR AIR POLLUTIONRADON

• 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