Indoor Air Quality In Your Home
This article appeared in the July 2001 edition of AAIA Ontario News.
There are numerous factors
in a home that can affect the health of its occupants. This article
is designed for the allergic/asthmatic to highlight some of the
Factors are presented
in a general order of theoretical and logical priority. In the real
world, however, priorities for your home may vary depending on problems
unique to your home or budget: can you afford to attack indoor air
quality in the whole home, or do you want to start with the allergic/asthmatic's
bedroom? In either case, you will likely need the advice of a specialist
in home inspection to help you prioritize your interventions.
Whether you decide to
go big or small in correcting indoor air quality (IAQ), a general
rule of thumb remains the AAIA's "3A's" approach:
Awareness - know what's causing your IAQ problem
Avoidance - remove sources causing your IAQ problem
Action - when IAQ can't be corrected by source removal alone,
add mechanical devices to correct problems.
Too Much Humidity:
Controlling Mould and Dust Mite Growth
Mould and dust mite allergens can be the cause of many breathing
symptoms, especially for the allergic/asthmatic. High humidity causes
mould and dust mites to multiply and thus is a priority focus for
correction throughout the many places in the home these can grow.
Mould is often detectable to the naked eye (e.g., black spots on
wood window frames, bathroom tiles, carpeting and walls). Other
potential mould growth areas are in ventilation equipment such as
air conditioning coils, humidifiers, air exchanges coils and dehumidifiers.
Basements are notorious for mould and dust mite problems. Being
below ground level increases the possibility of water infiltration.
This can be due to structural problems whereby the protective membrane
between the earth and the foundation wall fails to prevent water
from seeping through. Old homes that have had their windows upgraded
were not designed to be airtight and can trap humidity, leading
to mould growth in the areas of the home mentioned above.
How do you fix high humidity? Proper ventilation all year round
is crucial for controlling the problem.
and Pressurization: Controlling Humidity
Fall/Winter: In the winter, it is best to keep the humidity
level between 35-40%. Over 40% encourages dust mite and mould growth.
Homes in which newer, more hermetically sealed windows have been
installed may require the installation of an air exchanger or heat
recovery ventilator for fall and winter to ensure that the humid
air created by bathing, cooking and washing does not build up in
the home. Exhaust fans are required in bathrooms where bathing and
showering can trap humidity. Make sure to have adequate cubic feet
per minute of exhaust for the size bathroom being serviced.
Summer: The use
of a standard air exchanger or heat recover ventilator will not
be effective enough in lowering summer humidity because the air
outside is too humid at this time of year. The only possible function
of an air exchanger during the warmer season would be to continue
to ventilate the home with the windows and doors kept closed for
long period of time.
In summer, a portable, wall-mounted or central air conditioning
or a heat pump are necessary to lower humidity in indoor air. These
control the humidity level by condensing the air. It is possible
to dehumidify a home during the summer months using an active heat
recovery ventilator that is designed to condense the air. These
are more costly units than your standard air exchanger or heat recovery
ventilator and are for people who do not like cooling their home
but would like to dehumidify or temper the air during the summer
Ventilation can affect your comfort level in the home. Too cold
in one room, too hot in another; too much air in one room, not enough
in another. This is when you must call in a ventilation expert to
try to balance the air circulation as best possible.
A more serious problem is back drafting from fireplaces. This occurs
when potentially toxic particulate from the fireplace returns into
the home instead of moving up through the chimney. Again, consulting
with a professional in ventilation to determine if your home is
pressurized properly will ensure safe use of your fireplace.
Not Enough Humidity:
Enhancing the Body as an Air Filter
When people complain of irritated throats, itchy or chapped skin
or blocked noses, they may be living in a home with an insufficient
amount of humidity. These symptoms are not synonymous with low humidity,
however. Other factors such as poor air filtration, toxic gases,
mould or dust mite allergens can also lead to these symptoms.
To verify if low humidity is a problem in your home, it is recommended
that you buy a humidity gauge. If humidity is less than 30-35%,
it tends to dry out body fluids in the upper and lower airways,
moisture that is needed to filter air particles we breathe. You
will need to purchase either a humidifier that attaches to a central
ventilation system or strategically place portable units.
The type of portable humidifier that treats the water by boiling
it is recommended. If a central unit is preferred, either a flow-through,
padless drum type, or a steam humidifier will be better than the
old drum and pad type units where water sits in a pan and soaks
on the sponge, sometimes for days.
As mentioned earlier, however, humidifiers can be a breeding ground
for mould. Where there is moisture, mould will begin to form in
a short time. When standing water is not removed within 72 hours,
mould growth will occur rapidly and minor problems can quickly become
major. Make sure to be well informed on the maintenance required
to keep your humidifier in good repair and to clean it thoroughly
during and at the end of the low humidity season (in Canada, usually
Filtration is extremely important to breathing healthier air. You
need a filter than can capture very small airborne particles - those
particles which the human body cannot filter. Reducing airborne
particles enhances recuperation of the respiratory system during
a good night's sleep.
Of all the filters available on the market, only certain ones are
designed to actually trap very small particles (i.e., down to 0.3
microns). Electronic filters do so noiselessly and very well, but
beware. Their efficiency decreases with use and they thus require
regular and frequent cleaning to maintain filtering performance
over time. Electronic filters are known to produce ozone, a potent
respiratory irritant, as a by-product of being dirty. Keeping them
clean at all times is critical.
In recent years, the most recommended and popular filtering system
for asthma/allergy sufferers is a "media filter" system
called HEPA (high efficiency particulate arrester). This filter
medium will continuously capture very small airborne particles and
become even more efficient over time. It requires no cleaning and
does not produce ozone. HEPA units are available for central installation
or for single room use.
To make sure a HEPA unit is as good as a manufacturer says it is,
ask for a demonstration using a particle counter capable of measuring
concentrations of particles as small as 0.3 microns in size (1/25000
of an inch). If the air coming out of the unit does not capture
99.97% of particles 0.3 microns in size, the system does not meet
true HEPA performance criteria.
There are other media-type filters available on the market that
are less efficient than HEPA, but it is important that every home
has a filter on its ventilation system. A good rule of thumb when
buying a less efficient throw-away filter is - if salt can pass
through, it is not worth purchasing.
Most people never think to clean their ventilation equipment. That
is because not many people, including professionals in the business
of ventilation, are aware that cleaning equipment and products exist
to safely and effectively perform this task. There are many products
available that claim to completely disinfect a ventilation system.
Sadly, many of these products are made of toxic solutions that can
be harmful to the upper and lower airways. Moreover, the difficulty
of applying the product thoroughly renders them unreliable.
Decontaminating your ventilation system or portable ventilation
equipment is like going to the dentist to have your teeth cleaned.
Both are meant to protect against build-up of harmful substances.
While cleaning your teeth lessens the likelihood of gum disease,
decontaminating equipment lowers the risk of breathing contaminated
air, particularly with moulds.
Treating your ventilation equipment (air conditioning and heating
systems, portable and wall A/C units, dehumidifiers, humidifiers
and heat recovery ventilators) against mould and bacteria growth
before it reaches levels of toxicity that can adversely affect your
health is crucial to maintaining good air quality. This work can
be done in minutes, safely, using non-toxic products.
Other Indoor Air Pollutants
to Watch Out For
1) Off-Gassing of Toxic Fumes: Try to reduce use of toxic
cleaners - go "green" (nontoxic).
2) Household Clutter: Reducing household clutter makes it
easier to clean your home and help reduce dust mite buildup
3) Pets: Deciding on whether or not to keep a pet is always
a difficult subject. Tough decisions from time to time must be made
when compromised health of a loved on becomes an issue. If you have
pets, keep them away from bedrooms. Keep them clean and vacuum frequently
with either a HEPA filtered system or central vacuum that exhausts
to the exterior of the home.
4) Smoking: Smoking of tobacco products in the home should
be avoided at all times. Second-hand or environmental tobacco smoke
(ETS) can lead to asthma in young children. For up to a half-hour
after smoking, the smoker's exhalations continue to pollute the
spaces s/he occupies.
5) Incorrect Cleaning Procedure: When using a standard filtered
vacuum, pollutants sucked from the carpet go through the filter
and escape into the ambient air. Vacuuming should be done only with
an approved HEPA filter or central vacuum system which exhausts
its air to the exterior. When dusting, use an implement that traps
particles instead of stirring them up.
What are the factors that improve indoor air quality?
Proper dehumidification. Air exchanges and heat recovery units
should only be in operation for the purpose of dehumidification
when a lower humidity level outside will help reduce the humidity
level inside. Note that in summer, the only way to dehumidify a
home is by condensing the air. Air conditioning is recommended.
Install exhaust fans when necessary in bathrooms and kitchens.
Balance temperatures and relative humidity as best possible throughout
the home with ventilation equipment.
Make sure your home is not in negative pressure (looking for air,
or trying to suck it in from the outside through openings such as
Keep humidity between 35-40%. Use a portable or central system that
either produces humidity with steam or does not use standing water
and is easy to clean.
There are two levels of filtration - one for the ventilation system
(standard performance filter capable of filtering visible dust and
dirt) and one to protect the human respiratory system (such as a
high performance media filter capable of filtering particles down
to 0.3 microns in size).
Periodically, decontaminate and clean equipment using nontoxic solutions
that can effectively treat all areas including the duct distribution.
Verify mechanical performance by a trained professional.
Reduce Toxicity in
Use nontoxic cleaning products Make your home smoke-free.
Clean your Home Regularly
Vacuum and dust with technology that captures rather than stirs
up particles from surfaces. Remove or consider not introducing sources
of potential allergens. These include: carpeting, pets, stuffed
animals, fabric (e.g., upholstered furniture, drapes).
Improving and maintaining good indoor air quality is a challenge.
Establishing a relationship with a qualified specialist in home
inspection is critical in meeting it. For help finding someone qualified
in your area, contact:
The Heating, Refrigeration and Air Conditioning Institute of Canada
5045 Orbitor Drive, Building 11, Suite 300
Mississauga, ON L4W 3Y4
Tel: 1-800-267-2231 or (905) 602-4700
Web site: www.hrai.ca
HRAI is a partnership
of industry sector organizations that represents Heating, Ventilation,
Air Conditioning and Refrigeration (HVACR) manufacturers, wholesalers
and contractors who provide the Canadian public with products and
services for indoor comfort and essential refrigeration processes.
of Use: The information
on this site does not constitute medical advice and is for your
general information only. We cannot be held responsible for anything
you could possibly do or say because of information on this site.
Consult your family physician or allergist for specific questions
This article courtesy of the Allergy/Asthma
Information Association at www.aaia.ca and the Calgary Allergy Network
web site at www.calgaryallergy.ca. May be reproduced for educational,
non-profit purposes with proper attribution.
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