Transcript Indoor Air Quality - Oakland Community College

FSN 1500 Week 10
Indoor Air Quality
Foreword
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The quality of the air we breathe is both a
personal health and a major economic
issue
Most people don’t consider how vital the
quality of their indoor air is to their health,
so today we’ll focus on some important
indoor air quality concerns
Indoor Air Quality
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The average
Westerner spends
about 90% of their life
indoors!
Studies have shown
that indoor air may be
10 - 100 times more
polluted than outdoor
air!
Indoor Air Quality
Some indoor air
quality concerns
include: radon, the
combustion
pollutants and
asbestos.
Indoor Air Quality (Radon)
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Radon - colorless, odorless, radioactive gas
formed by the radioactive transformation of
uranium in soil and rock.
238U ---> 222Rn + heat + 4 4 He (alpha
particles) (see next slide)
Example of Radioactive Decay
http://www.ndted.org/EducationResources/HighSchool/Radiography/radioactiv
edecay.htm
Indoor Air Quality (Radon)
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Radon gas has a natural tendency to seep upward
through cracks in rocks and soil pore spaces; it may
even rise as a dissolved gas in groundwater
Radon enters a dwelling through cracks in the
foundation or concrete slab, through porous construction
materials (e.g., concrete), through uncapped sumps and
floor drains and through gaps between utilities and the
structure’s walls and floors (see figure)
The uranium content in soils and rocks and the amount
of radon released does vary
Indoor Air Quality (Radon)
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However, nearly every rock and soil type emits
some level of radon so every structure contains
some level of radon
The U.S. Environmental Protection Agency
(EPA) and the American Lung Association
contend that moderate to long-term exposure to
elevated levels of indoor radon and its
radioactive byproducts is the second-leading
cause of lung cancer
Indoor Air Quality (Radon)

According to the EPA and the U.S.
National Cancer Institute, cigarette
smoking is responsible for approximately
85% of lung cancer cases and prolonged
exposure to radon and its byproducts is
responsible for approximately 10% of lung
cancer cases
Indoor Air Quality (Radon)
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How could radon or its byproducts induce
lung cancer? The key concern is the
alpha particles and their potential to
mutate the DNA of the lung wall cells.
The alpha particle is not very energetic; its
penetration power is not great - even a
few centimeters of air dampens its energy
significantly (see figure)
Penetration energies of different types of nuclear radiation
Indoor Air Quality (Radon)
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However, if the alpha particle gets released into
our lung cavity, some alpha particles may have
enough energy to penetrate the first few
millimeters of the lung wall and cause mutations
in these cells
When the radon gas enters our dwellings it
mixes well with the other air gases; when you
inhale you could be inhaling some radon atoms
Indoor Air Quality (Radon)
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What’s the chance of a radon atom
undergoing radioactive decomposition and
releasing an alpha particle while in your
lungs? For the average adult only about a
1 in 15,000 chance!
Why so low a chance? We need to
examine the residence time of the radon in
the lungs and its half-life.
Indoor Air Quality (Radon)
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Most of any adult’s inhalation gases only
reside in the lungs about 30 seconds
before they’re exhaled or absorbed
Half-life: the time it takes one half of a
substance’s atoms to radioactively
transform
The measured half-life of radon is about
3.8 days
Indoor Air Quality (Radon)
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The 1 in 15,000 chance I mentioned earlier
results from the short residence time of the
radon in the lungs compared to the significantly
longer radon half-life
So why the concern over radon exposure
possibly inducing lung cancer?
The key: radon decomposes to two radioactive
solids - polonium-218 and polonium-214
Indoor Air Quality (Radon)
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Polonium-218 and polonium-214 have a
tendency to adhere to aerosols (e.g., dust
and smoke particles) and be drawn into
the lungs
Polonium-218 has a half-life of about 3
minutes, polonium-214 half-life is even
shorter; these elements decompose by
emitting an alpha particle
Indoor Air Quality (Radon)
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The lung residence time for aerosols in the
average adult is 30 minutes. Comparing
the residence time and polonium halflives, is it likely that alpha particles will be
released into the lung wall?
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Inexpensive, fairly accurate tests have been
developed to measure air radon levels but not
polonium levels; we assume the higher the air
radon level the higher the polonium levels
Indoor Air Quality (Radon)
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Indoor air radon levels are typically
measured in units of picoCuries per liter
(pCi/L); the picoCurie is a measure of
radioactivity, the liter a measure of air
volume
1 pCi/L corresponds to 133 radon atom
disintegrations in 1 liter of air in 1 hour
Indoor Air Quality (Radon)
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The U.S. EPA and other health agencies
suggest that structures with levels at 4 pCi/L or
greater have remediation work conducted
The World Health Organization’s action level for
remediation is 2 pCi/L
The following tables illustrate the relative death
risks for nonsmokers and smokers from longterm radon exposure
Radon Level
If 1,000 people who never
smoked were exposed to this
level over a lifetime*...
The risk of cancer from radon
exposure compares to**...
WHAT TO DO:
20 pCi/L
About 36 people could get lung
cancer
35 times the risk of drowning
Fix your home
10 pCi/L
About 18 people could get lung
cancer
20 times the risk of dying in a
home fire
Fix your home
8 pCi/L
About 15 people could get lung
cancer
4 times the risk of dying in a fall
Fix your home
4 pCi/L
About 7 people could get lung
cancer
The risk of dying in a car crash
Fix your home
2 pCi/L
About 4 person could get lung
cancer
The risk of dying from poison
Consider fixing between 2 and 4
pCi/L
1.3 pCi/L
About 2 people could get lung
cancer
(Average indoor radon level)
0.4 pCi/L
(Reducing radon levels below
2 pCi/L is difficult.)
(Average outdoor radon level)
Note: If you are a former smoker, your risk may be higher.
* Lifetime risk of lung cancer deaths from EPA Assessment of Risks from Radon in Homes (EPA 402-R-03-003).
** Comparison data calculated using the Centers for Disease Control and Prevention's 1999-2001 National Center for Injury
Prevention and Control Reports.
Radon Level
If 1,000 people who smoked
were exposed to this level
over a lifetime*...
The risk of cancer from radon
exposure compares to**...
WHAT TO DO:
Stop smoking and...
20 pCi/L
About 260 people could get lung
cancer
250 times the risk of drowning
Fix your home
10 pCi/L
About 150 people could get lung
cancer
200 times the risk of dying in a
home fire
Fix your home
8 pCi/L
About 120 people could get lung
cancer
30 times the risk of dying in a fall Fix your home
4 pCi/L
About 62 people could get lung
cancer
5 times the risk of dying in a car
crash
Fix your home
2 pCi/L
About 32 people could get lung
cancer
6 times the risk of dying from
poison
Consider fixing between 2 and 4
pCi/L
1.3 pCi/L
About 20 people could get lung
cancer
(Average indoor radon level)
(Reducing radon
levels below 2 pCi/L is difficult.)
0.4 pCi/L
About 3 people could get lung
cancer
(Average outdoor radon level)
Note: If you are a former smoker, your risk may be lower.
* Lifetime risk of lung cancer deaths from EPA Assessment of Risks from Radon in Homes (EPA 402-R-03-003).
** Comparison data calculated using the Centers for Disease Control and Prevention's 1999-2001 National Center for Injury
Prevention and Control Reports.
Indoor Air Quality (Radon)
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Indoor air radon levels as high as 3500
pCi/L have been measured; the outdoor
average level is 0.2 – 0.4 pCi/L
All indoor air pollution risks (not just radon)
are increased when we live under “closed
house” (windows and doors sealed tightly
and doors infrequently opened) conditions
(i.e., winter, portions of spring and fall)
Indoor Air Quality (Radon)
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The radon lung cancer risk is further enhanced if
significant aerosol production occurs within the
dwelling
If your structure contained elevated radon levels,
how could you possibly reduce these levels?
Two broad approaches: 1) improve crossventilation by natural or artificial means (e.g.,
sub-slab suction)
Indoor Air Quality (Radon)
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2) Seal or cover the radon entryways as
effectively as possible (e.g., caulking,
application of gas-impermeable paints,
installation of water permeable/gas
impermeable sump and floor drains)
There are also preconstruction radon
mitigation techniques which can be
employed (see figure for summary)
A = bed of
permeable gravel
(preconstruction)
B = gas impermeable
sheeting
(preconstruction)
C = caulk cracks and
utility openings
(usually post
construction)
D = Sub-slab
ventilation pipe
(usually post
construction)
E = ventilation fan
Indoor Air Quality (Radon)
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A dozen or so states now require indoor air
radon testing to be conducted before any
commercial or residential structure is sold.
How is this issue affected by Michigan's (mid1990s) enacted real estate transfer disclosure
statement?
Be forewarned: there is still much controversy,
perhaps unresolvable, concerning what radon
and radon byproduct exposure levels are
necessary to significantly increase lung cancer
risk.
Indoor Air Quality (Radon)
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Why the controversy? The only actual human
data we have is from studies of underground
uranium miners, typically exposed to higher
radon and radon byproduct levels for longer
periods than the average adult
There is definitely a linear (positive) relationship
between radon exposure and lung cancer
incidence for underground uranium miners
Indoor Air Quality (Radon)
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Can the risk relationship be linearly
extrapolated to lower exposure levels and
times to establish the lung cancer risk for
the general population? The U.S. EPA
thinks this is a valid approach - it employs
what is called a “linear” dose-response
model (see figure)
(Lung Cancer Incidence)
Response
Actual Data
Linear Model
Threshold Model
Dose
(Radon/Byproduct Exposure)
Indoor Air Quality (Radon)
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Some groups have argued that the appropriate
dose-response model is the “threshold” model
(see previous figure); this suggests the lung
cancer risk wouldn’t increase until a certain,
somewhat elevated combination of radon level
and exposure time was exceeded.
Why may we never be able to answer which
model is more appropriate? Why should we
care?
Indoor Air Quality (Radon)
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Broadly: we will likely never have the clinical
data to conclusively decide whether the linear or
threshold dose-response model is more
appropriate - yet we must try to make risk
assessments for substance exposures!
This issue illustrates the political and economic
aspects of science and how the layperson could
be mislead (see figures)
Detroit News 3/19/93
Indoor Air Quality (Radon)
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In 1998 the U.S. National Cancer Institute
scientists published a report that evaluated eight
previous studies on over 10,000 people in five
countries
Using a linear model approach, they estimated
a 14% increased chance of lung cancer for a
person living in a residence for 30 years that has
air radon levels of 4 pCi/L
Indoor Air Quality (Radon)
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What’s the status of the indoor air radon
problem in Michigan? There are definitely
“geographic hot spots” where elevated levels of
indoor radon have been measured
See the following figures - more detailed
information is available from the state
(Department of Natural Resources), federal
government (EPA) and the American Lung
Association
Michigan Radon Potential Map
High Potential
> 4 pCi/L
Moderate
Potential
2-4 pCi/L
Low Potential
< 2 pCi/L
Source: U.S. EPA, 2005
Indoor Air Quality (Radon)
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While the U.S. EPA and U.S. Geological
Survey suggest that only 6% of U.S.
households host air radon levels > 4 pCi/L;
note from the previous slides and your
handout that some geographic regions
may have a much higher percentage of
households whose air radon levels exceed
4 pCi/L
Indoor Air Quality (Radon)
• Short-term (days) and long-term (months)
air radon test kits are available; make sure
the kits are EPA approved
• A very good long-term (90 days to year) test
kit: Accustar Alpha Track AT 100 (~$20 and
available at Amazon.com)
Indoor Air Quality (Combustion
Pollutants)
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Combustion Pollutants - air pollutants resulting
when fossil fuels or other carbon-containing
fuels, or volatile organic compounds, are
inadequately combusted (e.g., not enough
oxygen present) or the combustion gases are
insufficiently vented
Major sources: wood stoves, fireplaces, coal
stoves, gas appliances (water heaters, cooking
ranges, clothes dryers, kerosene heaters,
camping cook stoves)
Example: 2 C(s) + O2(g)  2 CO(9) (carbon monoxide)
Indoor Air Quality (Combustion
Pollutants)
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Carbon monoxide (CO) - short term, the most
dangerous of the combustion pollutants; about
1100 people in the U.S., on the average, die
each year from accidental CO poisoning (early
1990’s Journal of the American Medical
Association report)
CO bonds about 250 times more effectively than
oxygen to the hemoglobin molecule in your
blood; the oxygen starvation to your organs can
result in death!
Indoor Air Quality (Combustion
Pollutants)
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CO is a colorless,
odorless gas; for the
average adult, exposure
to 400 ppm (parts per
million) concentrations of
CO for two hours results
in death
Be aware of low-level CO
exposure symptoms: flulike symptoms,
disorientation,
headaches, fatigue
Indoor Air Quality (Combustion
Pollutants)
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Health agencies suggest each home have one
or more CO monitors; the monitors are available
in two types: passive and active
Passive monitors require no power source
(battery or electrical cord) and typically consist
of a small, mountable disk whose surface
changes color as CO gases of different
concentrations pass over the disk (see figure)
Indoor Air Quality (Combustion
Pollutants)
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Although passive monitors are cheap, they are
useless unless you are visually monitoring them
Active monitors are available that use a battery,
electrical cord, or both, power source
See handout (and figures), some very good
active monitors are now available for sale
Indoor Air Quality (Combustion
Pollutants)
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The most versatile active CO monitors
have two power sources (electrical and
battery backup) and provide a digital
readout of CO levels (see figure)
Indoor Air Quality (Combustion
Pollutants)
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Why would health
and safety officials
urge that all
electrically powered
CO detectors be
equipped with a
backup battery? (see
figure)
12/18/2006
Indoor Air Quality (Combustion
Pollutants)
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Consumer
advocacy groups
(e.g., Consumer
Reports)
periodically rates
CO monitors (see
figure)
Indoor Air Quality (Combustion
Pollutants)
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Listen to the news or periodically scan the
Internet - like any other product, some CO
detectors have been recalled by their
manufacturers for failing to accurately
detect harmful levels of CO or for being
too sensitive (yielding false alarms)
Recent News
Note the
recent law
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Oakland Press
3/20/09
Be Aware
Any enclosed space
(automobiles, boats,
tents, hotel rooms)
could be a location
for carbon monoxide
poisoning
Indoor Air Quality (Combustion
Pollutants)
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Nitrogen dioxide (NO2) and sulfur dioxide (SO2)
combustion pollutants combine with air water
vapor to create respirable acidic sulfuric and
nitric acid aerosols
The acidic aerosols cause upper respiratory
irritation; the sulfuric acid aerosols are
threatening to people with asthma, allergies or
lung diseases like chronic bronchitis
Indoor Air Quality (Combustion
Pollutants)
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Formaldehyde - pungent gas (a volatile organic
compound); found in many household products
including foam insulation; resins in
particleboard, fiberboard and plywood paneling;
some carpeting, upholstery and drapery fabric;
and some plastics
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Exposure is commonly associated with eye, nose and
throat irritation; coughing, skin rashes, headaches,
nausea, vomiting and nosebleeds
Indoor Air Quality (Combustion
Pollutants)
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The EPA has
classified
formaldehyde as a
probable human
carcinogen (likely
lower risk)
Indoor Air Quality (Asbestos)
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Asbestos - collective
name for two families
of minerals that are
flexible, fire-resistant
and durable; one
group of minerals is
quite fibrous and the
other typically
consists of small,
brittle needles (see
figure)
Indoor Air Quality (Asbestos)
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Problem: most forms of asbestos can
exist as microscopic, respirable
particles that can remain airborne for
long periods
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Inhalation of asbestos particles, especially
the needlelike forms, cause lung tissue
scarring and is linked to several types of
cancer (lung (mesothelioma), stomach)
Indoor Air Quality (Asbestos)
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The asbestos fibers become airborne
typically as the product containing them
(e.g., pipe insulation) decomposes or is
fragmented (may happen accidentally or
during remodeling or demolition)
Unfortunately, health problems may not
become apparent until 15-40 years after
prolonged exposure
Indoor Air Quality (Asbestos)
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Most homes built prior to 1975
probably contain some asbestos in
floor or ceiling tiles, wall and pipe
insulation, wallboard and attic
insulation (see figure)
Indoor Air Quality (Asbestos)
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Local connection? Up to 700,000 Michigan
homeowners (12/6/04 Detroit Free Press, page
B1) may have attic insulation which contains
easily fragmented asbestos
The insulation has the product name Zonolite
and contains a mineral called vermiculite which
is contaminated with the more dangerous form
of asbestos
This product was even produced in a Dearborn,
MI processing plant from 1966-1990
Indoor Air Quality (Asbestos)
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The U.S. is not the
only country facing
this indoor air
quality problem.
Indoor Air Quality (Asbestos)
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During the late 1970s U.S. federal and
state regulations required removal of
identified asbestos-bearing materials studies found that large amounts of
asbestos became airborne during removal
of the materials and that these fibers
remained airborne for months
Indoor Air Quality (Asbestos)
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Today, encapsulation
of asbestos-bearing
materials by sealants
or enclosure
construction is
thought to be safer;
removal still done but
it increases risk of
accidental exposure
Be aware; this is still
a relevant issue
Related Issue
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During the 1950s and 1960s millions of tons of
asbestos waste were dumped into the Great Lakes
- this has raised concern over whether ingestion of
asbestos particles in drinking water could cause
stomach cancers
Indoor Air Quality
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Relatively inexpensive home test
kits exist for the indoor air pollutants
we discussed; contact the American
Lung Association or regional U.S.
EPA office for direction
Indoor air quality is both a health
and a business economic issue:
some buildings have been
abandoned or closed for costly
renovations because of associated
“sick building syndrome”
Indoor Air Quality
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Related note: the U.S. Centers for Disease
Control and Prevention stated in 2012 that an
estimated 25 million Americans have asthma
One possible contributing factor? More airtight
house construction resulting in less crossventilation and an increased exposure to indoor
air pollutants?