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Indoor Air Quality
Introduction
Professional builders strive to build homes that meet
the demands and needs of home buyers. As consumers
begin to learn more about indoor air quality, they
will start asking more of the home builder. Many consumers
are already asking about radon, and as consumer awareness
grows, they will be asking more about indoor air quality
in general. The purpose of this brief guide is to
give home builders, designers and developers, a general
understanding of indoor environmental quality and
ways to control it in new home construction so that
they can respond to growing consumer concerns
Recent research indicates that pollutant levels in
the air inside our homes and offices may be two to
five times higher than the air outside. Since people
spend 75 to 90 percent of their time indoors, the
quality of the indoor air has become a major concern.
Many of the adverse human health effects arising from
indoor air pollution are still not well understood.
Known discomfort, symptoms and health effects of exposure
to indoor air pollutants range from mild short-term
acute effects, such as sneezing, itchy eyes, and general
discomfort, to more serious long-term effects, such
as respiratory disorders and perhaps lung cancer.
Short-term high exposure to some pollutants, such
as carbon monoxide, can cause death. People react
differently to different types and levels of indoor
pollutants. Some people are very tolerant and rarely
experience discomfort or health problems; others are
more sensitive to indoor air pollutants.
The
National Institute of Allergy and Infectious Diseases
has estimated that 11 percent of us, or 22 million
Americans, suffer from allergies or asthma caused
primarily by reactions to pollen and spores. Allergies can be aggravated by house dust and other
pollutants. We are just beginning to recognize the
importance of indoor air quality concerns and ways
to address them. However, some steps have already
been taken to improve the quality of the air in the
indoor environment in new and existing residential
and commercial buildings.
Examples
of steps taken to improve Indoor Environmental Quality:
•
Radon resistant construction techniques are becoming
standard practice among many builders.
•
Lower formaldehyde-emitting products are being used
by many builders and in the manufacture of mobile
homes.
•
Asbestos-containing products have been banned or are
being phased out by rules issued by the EPA.
•
Lead in solder may not be used in public or private
drinking water systems.
•
Builders are learning about mechanical ventilation
as a way to control humidity and pollutants.
•
Electronic air filters have become a popular feature
of modern heating, ventilation, and air conditioning
(HVAC) systems.
•
Builders are using sealed combustion furnaces and
water heaters or forced draft in an effort to improve
energy efficiency and IAQ.
What
Are Principal Indoor Air Quality Concerns?
Air pollutants have always been present in the indoor-environment.
Serious short-term health effects have been alleged
and headaches, dizziness and other symptoms have been attributed to
higher concentrations of indoor air contaminants,
while the consequences of long-term exposure to low
levels of indoor pollutants is not known. The levels
reached indoors are a function of the presence of
pollutant sources, the strength of such sources, the
volume and mixing rate of enclosed spaces, indoor
moisture vapor and temperature, air exchange rates,
pollutant interaction and reactivity rates, and outdoor
air quality levels.
Air pollutants and their sources are numerous. Some
common indoor air pollutants are carbon monoxide,
nitrogen oxide, suspended particulates, formaldehyde
and other organic compounds, allergens, smoke, and
radon gas and its decay products or "progeny."
Sources of air pollutants are as varied and numerous
as the pollutants themselves.
Pollutants are generated indoors from sources such
as: fireplaces, woodstoves, smoking, solvents, cleaning
products, pesticides, pet dander, micro-organisms,
furnishings, certain building materials, water supplies,
surrounding soil, fossil-fuel-fired appliances, leaking
furnaces, chimneys, and outdoor air which may enter
an enclosed space as air borne gases or particles,
or carried inside as attached particles or dust.
Other factors which influence indoor air quality are
siting, weather, ventilation and infiltration, environmental
control systems, durability of materials, structure
contents, furnishings, structure maintenance, deterioration
of both structure and contents, design and human factors.
To address many of these indoor air quality concerns,
codes and/or basic standard building practice assure
the following conditions are met. If this is not the
case in your area, it is highly recommended that you
take it upon yourself to provide these basic features
in new homes:
•
A dry basement, with no mold or mildew problems;
• No elevated radon levels;
• No backdrafting of furnace, domestic water heater,
or fireplace;
• No lead containing paint or solder in the water
system;
• No asbestos;
• No unvented gas or kerosene appliances;
• Humidity (relative) maintained between 35 to 55
percent;
• Pesticides applied carefully, if required; and
• Kitchen, bathroom, and sometimes laundry room exhaust
fan vented to the outside.
Beyond basic code and standard building practices,
there are additional features a builder may choose
to offer as an upgrade package to enhance home marketability
by appealing to potential buyers with heightened indoor
air quality concerns. The upgrade package may include:
•
A ventilation system, with our without a heat recovery
system;
• High efficiency filtration systems for air and water;
• Central vacuum system that exhausts to the outdoors
(dust remains in the canister);
• Avoid the excessive use of building materials known
to emit formaldehyde and other gases, including hardwood
plywood, wall paneling, particleboard cabinets, and
carpet underlayment, paints, and finishes; and
• Non-toxic alternatives to pesticides.
Chemical
Sensitivity
For some of your clients who believe they are particularly
vulnerable to exposure to a wide variety of substances
even this upgrade package may not be sufficient. For
these people, special care needs to be taken to analyze
each product that is used in the building for potential
effects on the occupant and extreme care needs to
be taken in the construction, operation, and maintenance
of the home.
Homeowners must also pay close attention to the home's
contents. Some furnishings and decorator items may
emit significant levels of pollutants.
The
Healthy Home Association
is
the only organization in America
that provides the
"Healthy Home Certification".
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