The Basics of Indoor Air Quality (IAQ) Part I
The use of “green” building products and design stems from two concerns:
concern for the impact of our activities on our environment, and concern for the
impact our environment has on us. Increasingly, people recognize that
contamination of the air we breathe in our homes has significant consequences
for our health and quality of life. Quite literally, some people are made ill by their
houses.
IAQ related-illness is increasingly common in homes, offices, and commercial
buildings, it even has a name: Sick Building Syndrome. It could be that more
people are sensitized to the responsible agents; it’s also likely that we’ve become
more aware of IAQ problems and better at diagnosing them. Finally, it appears
that the energy-efficient construction methods we now use with the toxic building
materials we’ve always used, cause more problems now than in the past.
Causes of IAQ Problems
Many factors influence IAQ, but it boils down to the amount of toxins or pollutants
either entering or released by your home, and its ability to dilute or remove them.
How simple and cheap it is to address these problems? That’s very much a
function of the specific problem itself, and the design and the siting (choice of
specific location) of your home. This article lists some of the more common
problems, their causes, and some solutions.
How do I know if I have Problems?
IAQ problems can have both immediate and longer-term effects. Short term, you
may experience soreness of your eyes, nose, or throat; headache, dizzyness, or
fatigue. If you occasionally suffer from asthma, you may experience more
frequent or more severe attacks. If these symptoms appear at home – for
example, overnight – and diminish or disappear altogether when you leave the
house, you may have IAQ problems. Long-term, IAQ problems can lead to
respiratory disease, heart disease, or cancer.
A Simple Test
Many people report the worst symptoms when they wake up in the morning, after
their house has had a chance to “poison” them in their sleep. If this is true for
you, and if the nighttime temperature outside isn’t too extreme, there’s a simple
test you can try: put extra covers on your bed, and sleep with a window open. If
you wake up feeling significantly better, there’s a good chance your house has air
quality problems.
Inadequate Ventilation
A frequent cause of IAQ problems is inadequate ventilation. A steady influx of
fresh air into your house should dilute toxins and contaminants that build-up with
time. In an effort to make modern houses more energy efficient, we design them
with air barriers to reduce the amount of exterior air that leaks into them and the
amount of interior air that can escape. If the building envelope, as the
conditioned (heated and/or cooled) space inside your house is called, is nearly air-
tight, an entry point for fresh air has to be included in the home’s design.
Sometimes this fresh air vent is rendered inadequate by the addition of new
combustion devices (for example, an electric stove or clothes dryer is replaced by
a gas model), or the addition of new exhaust vents (e.g, a new bathroom fan or
range hood.) Sometimes air intake filters for furnaces and air conditioning clog.
(As you probably know, these should be changed regularly.) Sometimes the need
for makeup air is not properly addressed in a house’s design. More commonly,
remodeling increases these needs without addressing them.
In an effort to achieve acceptable IAQ while minimizing energy consumption, the
American Society of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE) recently revised its ventilation standard to provide a minimum of 15 cfm
of outdoor air per person (20 cfm/person in office spaces). Up to 60 cfm/person
may be required in some spaces (such as smoking lounges) depending on the
activities that normally occur in that space (see ASHRAE Standard 62-1989).
There is considerable debate as to how much airflow is enough. Regardless,
measuring your home’s ventilation rate requires special equipment. HVAC and
home performance specialists can do this for you.
“How can I possibly heat or cool my home with all this air blowing through it?” you
might well ask. Actually, adequate ventilation should – and can – be achieved in
energy efficient homes in all climates. In climates with extreme cold, heat recovery
ventilation (HRV) systems extract the heat from warm outgoing air and use it to
warm incoming cold air. In hot climates, energy recovery ventilation (ERV)
systems do the opposite: chill hot incoming air with cool, outgoing air.
Sources and additional information:
http://www.ashrae.org/
http://oikos.com/esb/39/VentOpt.html
http://www.hvi.org/
If all this air blasting through your home is an uncomfortable or depressing
thought, and you are either willing to undertake major renovations or are
considering building a new house, take heart: there are great alternatives.
Commonly used in much of Europe, radiant heating and cooling systems
combined with low-velocity fresh air distribution systems provide an efficient,
comfortable solution, even in the most extreme climates. Unfortunately, you won’t
find information on these systems in the above references. These systems are
generally considered in the design of zero-energy homes. See http://en.wikipedia.
org/wiki/Passivhaus.
Combustion By-products
Surely indoor air quality has improved drastically since our ancestors heated and
cooked with open fires in their caves. Nevertheless, the by-products of
combustion – including carbon monoxide – represent some of the more
dangerous IAQ problems. To protect occupants from combustion gases, building
codes require the majority of combustion appliances be direct or power-vented to
the outdoors. Unfortunately, none of these appliances works as intended without
sufficient fresh, outside air (makeup air.)
Power venting appliances mostly ensures that the by-products of combustion from
the appliances in question end-up outdoors, but it can have the unintended effect
of pulling in air from somewhere it shouldn’t. For example, a power vented
furnace can pull smoke out of a fireplace. The furnace wants fresh air; it will get it
by pulling it down the chimney if it has to.
If you experience headaches, dizzyness, burning eyes, nose or throat, and
particularly if you can correlate these problems to the operation of a particular
combustion appliance in your home, the first step (after attempting the “open
window” test described earlier, if practical) is to make a series of simple
inspections.
Check each appliance to see that the flue is properly connected and isn’t blocked
(by the nests or corpses of dead inspects, birds or rodents.) If you don’t find
anything that simple, try the “match” test on each combination of appliances: use
a lit match to indicate which direction air is flowing through the device. For the
power-vented furnace/fireplace example, turn the thermosat up to make sure the
furnace starts, and with no fire in the fireplace and the damper open, light a match
inside the fireplace. The match flame should stretch upward, indicating a strong
updraft in the chimney. If it stretches toward you, or is blown out, you know you
have a problem. Note: for gas appliances, if there is any possibility you have a
gas leak, don’t use a match or other flame!
VOCs and Off-gassing
A surprising number of everyday products in our homes contain toxic volatile
organic compounds (VOCs). Linked to short and long-term disease as minor as
headaches and as serious as death, these compounds include petroleum-derived
solvents, household cleaners like chlorine bleach and ammonia, and some natural
solvents like citrus solvent (“orange oil”). They’re found in vinyl products (e.g,
flooring, windows), carpet, paint, cabinets, counter tops, window drapes, air
fresheners and many others. Typically, the products off-gas this nasty stuff most
when brand-new, and do so less over time. Of those used widely in common
building materials, urea-formaldehyde is one of the worst. Found in plywood,
particleboard, medium density fiber board (MDF), laminate counter tops and other
pressed wood products, it releases toxic gas somewhat uniformly throughout its
life. Products that use phenol-formaldehyde are better. My understanding is that
they off-gas a great deal during manufacture, and relatively little thereafter. One
small piece of good news is that many of these products, like vinyl and air
fresheners, stink, making them easier to identify.
During renovations, consider wood-clad fiberglass or aluminum windows over
vinyl. Choose low- or no- VOC paints, cabinets, furniture, and counters. Ask that
countertops be installed with low VOC adhesives. Ditto for caulks and other
sealants. Look for low-VOC carpet or consider natural rugs and/or wood,
linoleum, cork, or bamboo flooring products. Avoid fabrics that have permanent
press treatments.
Another source of VOCs are chemicals that people intentionally bring into their
homes and apply: cleaners, polishes, paints, lacquers, perfumes, etc. Consider
using less toxic products for the same purposes.
The Attached Garage
The automobile is an explosive device filled with toxic chemicals—oil, gasoline,
antifreeze, brake fluid, and refrigerant, to name a couple. As if that weren’t
enough, it’s also a massive, air-consuming combustion device when it runs. The
gas-powered tools and usual array of chemicals people store in their garages are
worse. Building codes require that the wall(s) and door(s) shared between a
house and a garage be fire-rated for these reasons.
If air can move between your garage and house, toxic VOCs can move with it. At
the very least, they will follow you in through your garage entry door. If you have
living space above your garage, the chances of carbon monoxide and other auto
exhaust components getting into your house by convective means, through your
floor, are pretty good.
Make sure your garage is well-sealed from your home. For a standard attached
garage, the air barrier in shared wall(s) should extend floor to roof, not just floor to
ceiling. Weather stripping and an airtight seal around the doors, which code
requires to be self-closing for fire safety, are a must. Avoid idling vehicles in your
garage – start, gingerly back out, close the door, and then finish your warm-up.
If you live over your garage and can smell it, seal gaps and cracks with spray
foam. Pay particular attention around penetrations for wires and pipes.
Smoke
Tobacco and other types of smoke contains creosote, formaldehyde, and other
good stuff, all of which are carcinogens and can get trapped and re-released from
carpets, drapes, bedding, etc. If you are a smoking household, you’d be wise to
limit it to the garage or outdoors.
Radon
Radon is a radioactive gas released from uranium that can accumulate beneath
your house and enter it. You don’t have to live near a nuclear power plant or
waste storage facility for this to be a problem: uranium ores are found naturally in
many soils, particularly in some types of granite. A Geiger counter (radiation
meter) detects the problem. If you have a crawlspace, the solution is usually to
seal it and/or install vent stacks similar to the vent pipes on your roof that vent
your plumbing fixtures. Radon gas then dissipates above your roof instead of
entering your house.
Outdoor Contaminants
If you live near a busy street, your house can become contaminated by particulate
of brake linings, soot, and other auto combustion byproducts. Depending on
where you live, you may also get herbicides, pesticides and bacteria. If you suffer
from hayfever, pollen is also a concern. If your house is well-sealed, you may still
transport these contaminants into your house on your shoes and in your clothes.
If the air quality in your area is bad enough, you should use a 24/7, whole-house
ventilation system to filter all your incoming air. Avoid opening windows on bad air
days.
If you don’t have one, consider creating a “mud area” and removing your shoes
there before advancing further into your home. Shoe removal is widely practiced
outside the US. Besides improving your health, you may be astounded at how
much longer your house stays clean.
Lead
Lead-based paint is hard-wearing and very good at protecting surfaces.
Unfortunately, lead is extremely toxic. Lead paint was banned for residential use
in the U.S. in 1978. Any paint applied prior to that date should be suspect until
tested. Home lead test kits are available, but not reliable. Best is to collect an
appropriate sample and send it to a lab.
Remediation methods include painting over the lead paint, and removing it.
Removal requires significant safety precautions, since the risk of lead poisoning is
greatly elevated until all the paint is gone. Don’t attempt it yourself; hire
professionals.
Other countries have not been so quick to ban lead in paint. Imported children’s
toys may be painted with led paint. Inexpensive jewelry may contain significant
quantities of lead.
Sources and additional information: http://en.wikipedia.org/wiki/Lead_paint
Asbestos
Once regarded as a miracle flame-retardant additive, asbestos was once used in
everything from construction materials to children’s pajamas. Exposure to airborn
asbestos fibers, even short-term, can be harmful or deadly. Risk is proportional
to exposure: the greater the concentration and/or the longer the time of exposure,
the greater the harm. Once airborn, asbestos fibers enter and damage the lungs.
The U.S. instituted a ban and phase-out of asbestos in 1989, which then became
a partial ban in 1991. Asbestos is particularly prevalent in building materials.
Some types of building materials are still manufactured in the U.S. with asbestos.
Other products containing asbestos are manufactured elsewhere and imported to
the U.S. Just to give you an idea, products that can contain asbestos include:
sprayed-on insulation (acoustical, thermal, decorative, etc), sheetrock patching or
taping compound, insulation around heat sources (e.g., stoves and fireplaces),
electrical insulation, pipe coverings, vinyl sheet flooring (backing), roofing and
siding, fireproof curtains.
Sources and additional information:
http://www.epa.gov/iaq/asbestos.html#Sources%20of%20Asbestos
http://en.wikipedia.org/wiki/Asbestos
More Resources
For more information on IAQ Problems, see the US EPA website: http://www.epa.
gov/iaq/ia-intro.html
The use of “green” building products and design stems from two concerns:
concern for the impact of our activities on our environment, and concern for the
impact our environment has on us. Increasingly, people recognize that
contamination of the air we breathe in our homes has significant consequences
for our health and quality of life. Quite literally, some people are made ill by their
houses.
IAQ related-illness is increasingly common in homes, offices, and commercial
buildings, it even has a name: Sick Building Syndrome. It could be that more
people are sensitized to the responsible agents; it’s also likely that we’ve become
more aware of IAQ problems and better at diagnosing them. Finally, it appears
that the energy-efficient construction methods we now use with the toxic building
materials we’ve always used, cause more problems now than in the past.
Causes of IAQ Problems
Many factors influence IAQ, but it boils down to the amount of toxins or pollutants
either entering or released by your home, and its ability to dilute or remove them.
How simple and cheap it is to address these problems? That’s very much a
function of the specific problem itself, and the design and the siting (choice of
specific location) of your home. This article lists some of the more common
problems, their causes, and some solutions.
How do I know if I have Problems?
IAQ problems can have both immediate and longer-term effects. Short term, you
may experience soreness of your eyes, nose, or throat; headache, dizzyness, or
fatigue. If you occasionally suffer from asthma, you may experience more
frequent or more severe attacks. If these symptoms appear at home – for
example, overnight – and diminish or disappear altogether when you leave the
house, you may have IAQ problems. Long-term, IAQ problems can lead to
respiratory disease, heart disease, or cancer.
A Simple Test
Many people report the worst symptoms when they wake up in the morning, after
their house has had a chance to “poison” them in their sleep. If this is true for
you, and if the nighttime temperature outside isn’t too extreme, there’s a simple
test you can try: put extra covers on your bed, and sleep with a window open. If
you wake up feeling significantly better, there’s a good chance your house has air
quality problems.
Inadequate Ventilation
A frequent cause of IAQ problems is inadequate ventilation. A steady influx of
fresh air into your house should dilute toxins and contaminants that build-up with
time. In an effort to make modern houses more energy efficient, we design them
with air barriers to reduce the amount of exterior air that leaks into them and the
amount of interior air that can escape. If the building envelope, as the
conditioned (heated and/or cooled) space inside your house is called, is nearly air-
tight, an entry point for fresh air has to be included in the home’s design.
Sometimes this fresh air vent is rendered inadequate by the addition of new
combustion devices (for example, an electric stove or clothes dryer is replaced by
a gas model), or the addition of new exhaust vents (e.g, a new bathroom fan or
range hood.) Sometimes air intake filters for furnaces and air conditioning clog.
(As you probably know, these should be changed regularly.) Sometimes the need
for makeup air is not properly addressed in a house’s design. More commonly,
remodeling increases these needs without addressing them.
In an effort to achieve acceptable IAQ while minimizing energy consumption, the
American Society of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE) recently revised its ventilation standard to provide a minimum of 15 cfm
of outdoor air per person (20 cfm/person in office spaces). Up to 60 cfm/person
may be required in some spaces (such as smoking lounges) depending on the
activities that normally occur in that space (see ASHRAE Standard 62-1989).
There is considerable debate as to how much airflow is enough. Regardless,
measuring your home’s ventilation rate requires special equipment. HVAC and
home performance specialists can do this for you.
“How can I possibly heat or cool my home with all this air blowing through it?” you
might well ask. Actually, adequate ventilation should – and can – be achieved in
energy efficient homes in all climates. In climates with extreme cold, heat recovery
ventilation (HRV) systems extract the heat from warm outgoing air and use it to
warm incoming cold air. In hot climates, energy recovery ventilation (ERV)
systems do the opposite: chill hot incoming air with cool, outgoing air.
Sources and additional information:
http://www.ashrae.org/
http://oikos.com/esb/39/VentOpt.html
http://www.hvi.org/
If all this air blasting through your home is an uncomfortable or depressing
thought, and you are either willing to undertake major renovations or are
considering building a new house, take heart: there are great alternatives.
Commonly used in much of Europe, radiant heating and cooling systems
combined with low-velocity fresh air distribution systems provide an efficient,
comfortable solution, even in the most extreme climates. Unfortunately, you won’t
find information on these systems in the above references. These systems are
generally considered in the design of zero-energy homes. See http://en.wikipedia.
org/wiki/Passivhaus.
Combustion By-products
Surely indoor air quality has improved drastically since our ancestors heated and
cooked with open fires in their caves. Nevertheless, the by-products of
combustion – including carbon monoxide – represent some of the more
dangerous IAQ problems. To protect occupants from combustion gases, building
codes require the majority of combustion appliances be direct or power-vented to
the outdoors. Unfortunately, none of these appliances works as intended without
sufficient fresh, outside air (makeup air.)
Power venting appliances mostly ensures that the by-products of combustion from
the appliances in question end-up outdoors, but it can have the unintended effect
of pulling in air from somewhere it shouldn’t. For example, a power vented
furnace can pull smoke out of a fireplace. The furnace wants fresh air; it will get it
by pulling it down the chimney if it has to.
If you experience headaches, dizzyness, burning eyes, nose or throat, and
particularly if you can correlate these problems to the operation of a particular
combustion appliance in your home, the first step (after attempting the “open
window” test described earlier, if practical) is to make a series of simple
inspections.
Check each appliance to see that the flue is properly connected and isn’t blocked
(by the nests or corpses of dead inspects, birds or rodents.) If you don’t find
anything that simple, try the “match” test on each combination of appliances: use
a lit match to indicate which direction air is flowing through the device. For the
power-vented furnace/fireplace example, turn the thermosat up to make sure the
furnace starts, and with no fire in the fireplace and the damper open, light a match
inside the fireplace. The match flame should stretch upward, indicating a strong
updraft in the chimney. If it stretches toward you, or is blown out, you know you
have a problem. Note: for gas appliances, if there is any possibility you have a
gas leak, don’t use a match or other flame!
VOCs and Off-gassing
A surprising number of everyday products in our homes contain toxic volatile
organic compounds (VOCs). Linked to short and long-term disease as minor as
headaches and as serious as death, these compounds include petroleum-derived
solvents, household cleaners like chlorine bleach and ammonia, and some natural
solvents like citrus solvent (“orange oil”). They’re found in vinyl products (e.g,
flooring, windows), carpet, paint, cabinets, counter tops, window drapes, air
fresheners and many others. Typically, the products off-gas this nasty stuff most
when brand-new, and do so less over time. Of those used widely in common
building materials, urea-formaldehyde is one of the worst. Found in plywood,
particleboard, medium density fiber board (MDF), laminate counter tops and other
pressed wood products, it releases toxic gas somewhat uniformly throughout its
life. Products that use phenol-formaldehyde are better. My understanding is that
they off-gas a great deal during manufacture, and relatively little thereafter. One
small piece of good news is that many of these products, like vinyl and air
fresheners, stink, making them easier to identify.
During renovations, consider wood-clad fiberglass or aluminum windows over
vinyl. Choose low- or no- VOC paints, cabinets, furniture, and counters. Ask that
countertops be installed with low VOC adhesives. Ditto for caulks and other
sealants. Look for low-VOC carpet or consider natural rugs and/or wood,
linoleum, cork, or bamboo flooring products. Avoid fabrics that have permanent
press treatments.
Another source of VOCs are chemicals that people intentionally bring into their
homes and apply: cleaners, polishes, paints, lacquers, perfumes, etc. Consider
using less toxic products for the same purposes.
The Attached Garage
The automobile is an explosive device filled with toxic chemicals—oil, gasoline,
antifreeze, brake fluid, and refrigerant, to name a couple. As if that weren’t
enough, it’s also a massive, air-consuming combustion device when it runs. The
gas-powered tools and usual array of chemicals people store in their garages are
worse. Building codes require that the wall(s) and door(s) shared between a
house and a garage be fire-rated for these reasons.
If air can move between your garage and house, toxic VOCs can move with it. At
the very least, they will follow you in through your garage entry door. If you have
living space above your garage, the chances of carbon monoxide and other auto
exhaust components getting into your house by convective means, through your
floor, are pretty good.
Make sure your garage is well-sealed from your home. For a standard attached
garage, the air barrier in shared wall(s) should extend floor to roof, not just floor to
ceiling. Weather stripping and an airtight seal around the doors, which code
requires to be self-closing for fire safety, are a must. Avoid idling vehicles in your
garage – start, gingerly back out, close the door, and then finish your warm-up.
If you live over your garage and can smell it, seal gaps and cracks with spray
foam. Pay particular attention around penetrations for wires and pipes.
Smoke
Tobacco and other types of smoke contains creosote, formaldehyde, and other
good stuff, all of which are carcinogens and can get trapped and re-released from
carpets, drapes, bedding, etc. If you are a smoking household, you’d be wise to
limit it to the garage or outdoors.
Radon
Radon is a radioactive gas released from uranium that can accumulate beneath
your house and enter it. You don’t have to live near a nuclear power plant or
waste storage facility for this to be a problem: uranium ores are found naturally in
many soils, particularly in some types of granite. A Geiger counter (radiation
meter) detects the problem. If you have a crawlspace, the solution is usually to
seal it and/or install vent stacks similar to the vent pipes on your roof that vent
your plumbing fixtures. Radon gas then dissipates above your roof instead of
entering your house.
Outdoor Contaminants
If you live near a busy street, your house can become contaminated by particulate
of brake linings, soot, and other auto combustion byproducts. Depending on
where you live, you may also get herbicides, pesticides and bacteria. If you suffer
from hayfever, pollen is also a concern. If your house is well-sealed, you may still
transport these contaminants into your house on your shoes and in your clothes.
If the air quality in your area is bad enough, you should use a 24/7, whole-house
ventilation system to filter all your incoming air. Avoid opening windows on bad air
days.
If you don’t have one, consider creating a “mud area” and removing your shoes
there before advancing further into your home. Shoe removal is widely practiced
outside the US. Besides improving your health, you may be astounded at how
much longer your house stays clean.
Lead
Lead-based paint is hard-wearing and very good at protecting surfaces.
Unfortunately, lead is extremely toxic. Lead paint was banned for residential use
in the U.S. in 1978. Any paint applied prior to that date should be suspect until
tested. Home lead test kits are available, but not reliable. Best is to collect an
appropriate sample and send it to a lab.
Remediation methods include painting over the lead paint, and removing it.
Removal requires significant safety precautions, since the risk of lead poisoning is
greatly elevated until all the paint is gone. Don’t attempt it yourself; hire
professionals.
Other countries have not been so quick to ban lead in paint. Imported children’s
toys may be painted with led paint. Inexpensive jewelry may contain significant
quantities of lead.
Sources and additional information: http://en.wikipedia.org/wiki/Lead_paint
Asbestos
Once regarded as a miracle flame-retardant additive, asbestos was once used in
everything from construction materials to children’s pajamas. Exposure to airborn
asbestos fibers, even short-term, can be harmful or deadly. Risk is proportional
to exposure: the greater the concentration and/or the longer the time of exposure,
the greater the harm. Once airborn, asbestos fibers enter and damage the lungs.
The U.S. instituted a ban and phase-out of asbestos in 1989, which then became
a partial ban in 1991. Asbestos is particularly prevalent in building materials.
Some types of building materials are still manufactured in the U.S. with asbestos.
Other products containing asbestos are manufactured elsewhere and imported to
the U.S. Just to give you an idea, products that can contain asbestos include:
sprayed-on insulation (acoustical, thermal, decorative, etc), sheetrock patching or
taping compound, insulation around heat sources (e.g., stoves and fireplaces),
electrical insulation, pipe coverings, vinyl sheet flooring (backing), roofing and
siding, fireproof curtains.
Sources and additional information:
http://www.epa.gov/iaq/asbestos.html#Sources%20of%20Asbestos
http://en.wikipedia.org/wiki/Asbestos
More Resources
For more information on IAQ Problems, see the US EPA website: http://www.epa.
gov/iaq/ia-intro.html