Indoor Air Pollution: Radon - PowerPoint PPT Presentation

About This Presentation
Title:

Indoor Air Pollution: Radon

Description:

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. – PowerPoint PPT presentation

Number of Views:44

less

Transcript and Presenter's Notes

Title: 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
Write a Comment
User Comments (0)
About PowerShow.com