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Indoor
Air Quality
Indoor
Air Quality (IAQ) is a current buzzword in the Heating,
Ventilation and Air Conditioning (HVAC) Industry.
We hear about
Legionnaire's disease outbreaks traced to the air conditioning system.
Buildings are highlighted on the news as making their tenants sick and
it's referred to as sick building syndrome. Individual homes are
linked to increases in allergies and asthma. Can it happen to your
home and what can you do to prevent it or correct it if you are
already the proud owner of a house that is making you sick?
The
ever-increasing cases of sick building syndrome are due to the way
houses and buildings are constructed to conserve energy. Stop air
movement in and out of the home and you reduce the energy required to
heat and cool the house. After you seal the house up, central cooling
and heating systems maintain livable temperatures and humidity levels
within the home by re-circulation of the same air and pollutants day
after day. Dust, bacteria, viruses, mold, fungus, mildew and gases
circulate through the building. The dust can come from skin, hair,
clothes or just come off shoes when we walk in and out. The mildew,
fungus and molds can come in along with the dust or we can grow our
own in the HVAC system. The gases are volatile organic compounds that
are given off by dyes, paints, varnishes and adhesives used in modern
building materials. The best example of gases is that burning eye
sensation we get after new carpet is installed. So let's look at
Filtering The Dust,
Killing
the Mildew,
Molds,
Fungus,
Bacteria,
and
Viruses
and
Ventilating the Volatile Gases
in an attempt to breathe easier.
Filtering the Air We Breathe
The most
important step in filter improvement is to make sure that all the
air that goes through the electric air handler or gas furnace is
filtered.
If your HVAC system is pulling air through cracks in the duct system
or return air chase, it pulls the contaminates along with it. Have
your service technician check to verify that all the return air to a
system is pulled through the filter system. This is a good time for
your service technician to verify that the filter system is sized
large enough for proper operation of the system.
Filters come in
different efficiencies that are measured in the percentage of
arrestance of particles. Simply stated, what amount and size of
particles do they stop? The higher the percentage, the smaller the
particle the filter will stop. The other factor that must be
considered is the resistance to air flow, or will this super filter
let enough air through to allow my system to function properly?
Fiberglass
- these are the most inexpensive filters that you can buy. Most
people refer to them as the filter you can see through. They stop 15
% of the largest particles in the air. Replace monthly.
Pleated Paper
- these filters look like a paper version of drapery pleats and stop
up to 45% of the particles in the air. This type filter is the
easiest upgrade for the money spent. These filters come in the same
size as a fiberglass filter and are available at most hardware/home
improvement stores. This type of filter gives the greatest degree of
improvement for the money spent. Replace every 1 to 3 months.
Media Filter
- these filters are up to 4 inches thick and come in limited sizes,
though the size selection is increasing. Rated at 90 to 95 %
efficiency, these filters are changed 2 to 3 times a year. Media
filters require a special frame to be mounted in the wall or mounted
directly to the furnace or air handler. There are some media filters
that come with special adapters that allow them to be mounted in a
standard filter frame that has 4 inches of clearance behind it.
Electrostatic
filters
- As an upgrade to Fiberglass filters, these are made up of layers
of synthetic material that generate an electrical charge to attract
dust particles. Electrostatic filters come with guarantees from five
years to life. There have been problems due to high restriction of
airflow across the filter. This reduction of airflow can greatly
reduce the system capacity and efficiency. A new generation of these
filters is now coming to market that promises less restriction to
airflow. Clean at intervals of between 1 to 4 weeks.
Electronic Air
Filters
- this is the premiere filter system on the market today. An
electrostatic grid is powered when the AC or heat comes on and
attracts particles to it. The grid is cleaned as needed with a water
hose or in the dishwasher. This is the most efficient filter system
available. This type of filter normally fits the same space as a
Fiberglass filter, but does require modification to the ductwork and
wiring to be installed in your air conditioning system.
Some contractors
pre-filter either the media or the electronic filter with a pleated
paper filter and move their cleaning or replacement to a yearly
schedule. The main idea regardless of the type of filter you choose
is to filter all the air you circulate in your house and to remove
as much dust and other particles as needed to breathe comfortably.
One benefit of the high efficiency filters is a reduction in the
need to dust the furniture.
Killing the Mildew, Molds, Fungus,
Bacteria, and Viruses
One of the ways
our air conditioning system keeps us comfortable is by removing the
water vapor (humidity) from the air. As the AC system condenses
moisture from the air, a drain is supposed to take this moisture out
of the system. What really happens is that some of this water
splashes on the interior insulation and some of it is left standing
in the bottom of the pan that is not designed or installed to get it
completely out of the system. So, now, we have moisture ready to
support the growth of assorted micro-organisms that will cause a
variety of respiratory problems.
The simplest
treatment is to keep drain lines clear and to have a positive
drainage on the coil. Pan tablets and drain pads are available that
release chemicals into the condensed water and kills the pathogens.
These tablets or pads must be physically placed in the evaporator
drain pan on a 1 to 6 month schedule.
UV lights are the
newest tool to be used to improve indoor air quality. Similar to the
lights that barbers, dentists, and doctors use to sterilize their
instruments, these lights are designed to not only kill what's
growing in the drain pan, but also what is growing on the coil
surface or on the interior insulation. These lights will kill the
source of numerous allergens that people did not know existed. The
light shines on the inside of the AC, in front of the coil, 24 hours
a day. Even if a new bulb is required every year, the UV light
combined with a good filter system will greatly improve the quality
of air in either a home or business.
Even older air
conditioning units can usually be retrofitted with UV lights.
Ventilating
Gases
As home
construction has produced tighter homes, reaction to gases released
from building materials has increased. The trick is to bring in
fresh air without having to heat, cool or dehumidify it. This can be
accomplished in several ways and must be routed through the filter
system.
Heat Exchangers
- exhaust air is pushed through a tubular heat exchanger as fresh
air is pulled in around the outside of the tubes, allowing the air
to exchange heat. The exchanger does not bring hot air down to room
temperature or cold air up to room temperature but does reduce the
temperature difference and the energy needed to bring it to the
desired temperature. This solution guarantees fresh air will enter
the house and stale air will be exhausted along with the toxic
gases.
Desiccant
Wheels
- similar to heat exchangers but use a rotating wheel to remove
humidity from the incoming air and add it to the exhausted air.
Desiccant wheels will be used were humidity is the greater problem;
heat exchangers will be used where low winter temperatures are the
greatest problem.
Conclusion
In conclusion,
these various methods to improve air quality can be built into a new
or replacement system at the time of installation to achieve the
best-cost savings. Any of these improvements can also be added to an
existing system. You may find relief with just improving your filter
system or with a filter and an ultraviolet light. However you mix
and match to achieve breathable air, your licensed HVAC contractor
can provide you with the needed expertise and quality equipment to
accomplish the job.
Indoor pollution
Indoor pollution sources that release
gases or particles into the air are the primary cause of indoor air
quality problems in homes.
Inadequate ventilation can increase
indoor pollutant levels by not bringing in enough outdoor air to
dilute emissions from indoor sources and by not carrying indoor air
pollutants out of the home. High temperature and humidity levels can
also increase concentrations of some pollutants.
Pollutant Sources
There are many sources of indoor air
pollution in any home. These include combustion sources such as oil,
gas, kerosene, coal, wood, and tobacco products; building materials
and furnishings as diverse as deteriorated, asbestos-containing
insulation, wet or damp carpet, and cabinetry or furniture made of
certain pressed wood products; products for household cleaning and
maintenance, personal care, or hobbies; central heating and cooling
systems and humidification devices; and outdoor sources such as
radon, pesticides, and outdoor air pollution.
The relative importance of any single
source depends on how much of a given pollutant it emits and how
hazardous those emissions are. In some cases, factors such as how
old the source is and whether it is properly maintained are
significant. For example, an improperly adjusted gas stove can emit
significantly more carbon monoxide than one that is properly
adjusted.
Some sources, such as building
materials, furnishings, and household products like air fresheners,
release pollutants more or less continuously. Other sources, related
to activities carried out in the home, release pollutants
intermittently. These include smoking, the use of unvented or
malfunction-ing stoves, furnaces, or space heaters, the use of
solvents in cleaning and hobby activities, the use of paint
strippers in redecorating activities, and the use of cleaning
products and pesticides in housekeeping. High pollutant
concentrations can remain in the air for long periods after some of
these activities.
Indoor Ventilations
If too little outdoor air enters a home,
pollutants can accumulate to levels that can pose health and comfort
problems.
Unless they are built with special
mechanical means of ventilation, homes that are designed and
constructed to minimize the amount of outdoor air that can "leak" into
and out of the home may have higher pollutant levels than other homes.
However, because some weather conditions can drastically reduce the
amount of outdoor air that enters a home, pollutants can build up even
in homes that are normally considered "leaky."
How Does Outdoor Air Enter a
House?
Outdoor air enters and leaves a house
by: infiltration, natural ventilation, and mechanical ventilation.
In a process known as infiltration, outdoor air flows into the house
through openings, joints, and cracks in walls, floors, and ceilings,
and around windows and doors. In natural ventilation, air moves
through opened windows and doors. Air movement associated with
infiltration and natural ventilation is caused by air temperature
differences between indoors and outdoors and by wind. Finally, there
are a number of mechanical ventilation devices, from outdoor-vented
fans that intermittently remove air from a single room, such as
bathrooms and kitchen, to air handling systems that use fans and
duct work to continuously remove indoor air and distribute filtered
and conditioned outdoor air to strategic points throughout the
house. The rate at which outdoor air replaces indoor air is
described as the air exchange rate. When there is little
infiltration, natural ventilation, or mechanical ventilation, the
air exchange rate is low and pollutant levels can increase.
What If You Live in an Apartment?
Apartments can have the same indoor
air problems as single-family homes because many of the pollution
sources, such as the interior building materials, furnishings, and
household products, are similar. Indoor air problems similar to
those in offices are caused by such sources as contaminated
ventilation systems, improperly placed outdoor air intakes, or
maintenance activities.
Solutions to air quality problems in
apartments, as in homes and offices, involve such actions as:
eliminating or controlling the sources of pollution, increasing
ventilation, and installing air cleaning devices. Often a resident
can take the appropriate action to improve the indoor air quality by
removing a source, altering an activity, unblocking an air supply
vent, or opening a window to temporarily increase the ventilation;
in other cases, however, only the building owner or manager is in a
position to remedy the problem. You can encourage building
management to follow guidance in EPA and NIOSH's Building Air
Quality: A Guide for Building Owners and Facility Managers
Health Concerns
Health effects from indoor air
pollutants may be experienced soon after exposure or, possibly, years
later.
Immediate effects may show up after a
single exposure or repeated exposures. These include irritation of the
eyes, nose, and throat, headaches, dizziness, and fatigue.
Immediate Effects
Such immediate effects are usually
short-term and treatable. Sometimes the treatment is simply
eliminating the person's exposure to the source of the pollution, if
it can be identified. Symptoms of some diseases, including asthma,
hypersensitivity pneumonitis, and humidifier fever, may also show up
soon after exposure to some indoor air pollutants.
The likelihood of immediate reactions
to indoor air pollutants depends on several factors. Age and
preexisting medical conditions are two important influences. In
other cases, whether a person reacts to a pollutant depends on
individual sensitivity, which varies tremendously from person to
person. Some people can become sensitized to biological pollutants
after repeated exposures, and it appears that some people can become
sensitized to chemical pollutants as well.
Symptoms
Certain immediate effects are similar
to those from colds or other viral diseases, so it is often
difficult to determine if the symptoms are a result of exposure to
indoor air pollution. For this reason, it is important to pay
attention to the time and place the symptoms occur. If the symptoms
fade or go away when a person is away from the home and return when
the person returns, an effort should be made to identify indoor air
sources that may be possible causes. Some effects may be made worse
by an inadequate supply of outdoor air or from the heating, cooling,
or humidity conditions prevalent in the home.
Long-term Effects
Other health effects may show up
either years after exposure has occurred or only after long or
repeated periods of exposure. These effects, which include some
respiratory diseases, heart disease, and cancer, can be severely
debilitating or fatal. It is prudent to try to improve the indoor
air quality in your home even if symptoms are not noticeable.
While pollutants commonly found in
indoor air are responsible for many harmful effects, there is
considerable uncertainty about what concentrations or periods of
exposure are necessary to produce specific health problems. People
also react very differently to exposure to indoor air pollutants.
Further research is needed to better understand which health effects
occur after exposure to the average pollutant concentrations found
in homes and which occur from the higher concentrations that occur
for short periods of time.
Identifying Air Quality Problems
Some health effects can be useful indicators of an indoor air quality
problem, especially if they appear after a person moves to a new
residence, remodels or refurnishes a home, or treats a home with
pesticides.
If you think that you have symptoms that
may be related to your home environment, discuss them with your doctor
or your local health department to see if they could be caused by
indoor air pollution. You may also want to consult a board-certified
allergist or an occupational medicine specialist for answers to your
questions.
Another way to judge whether your home
has or could develop indoor air problems is to identify potential
sources of indoor air pollution. Although the presence of such sources
does not necessarily mean that you have an indoor air quality problem,
being aware of the type and number of potential sources is an
important step toward assessing the air quality in your home.
A third way to decide whether your home
may have poor indoor air quality is to look at your lifestyle and
activities. Human activities can be significant sources of indoor air
pollution. Finally, look for signs of problems with the ventilation in
your home. Signs that can indicate your home may not have enough
ventilation include moisture condensation on windows or walls, smelly
or stuffy air, dirty central heating and air cooling equipment, and
areas where books, shoes, or other items become moldy. To detect odors
in your home, step outside for a few minutes, and then upon reentering
your home, note whether odors are noticeable.
How to improve
These three basic strategies should be
utilized:
Source Control
Usually the most effective way to
improve indoor air quality is to eliminate individual sources of
pollution or to reduce their emissions. Some sources, like those
that contain asbestos, can be sealed or enclosed; others, like gas
stoves, can be adjusted to decrease the amount of emissions. In many
cases, source control is also a more cost-efficient approach to
protecting indoor air quality than increasing ventilation because
increasing ventilation can increase energy costs. Specific sources
of indoor air pollution in your home are listed later in this
section.
Ventilation Improvements
Another approach to lowering the
concentrations of indoor air pollutants in your home is to increase
the amount of outdoor air coming indoors. Most home heating and
cooling systems, including forced air heating systems, do not
mechanically bring fresh air into the house. Opening windows and
doors, operating window or attic fans, when the weather permits, or
running a window air conditioner with the vent control open
increases the outdoor ventilation rate. Local bathroom or kitchen
fans that exhaust outdoors remove contaminants directly from the
room where the fan is located and also increase the outdoor air
ventilation rate.
It is particularly important to take
as many of these steps as possible while you are involved in
short-term activities that can generate high levels of
pollutants--for example, painting, paint stripping, heating with
kerosene heaters, cooking, or engaging in maintenance and hobby
activities such as welding, soldering, or sanding. You might also
choose to do some of these activities outdoors, if you can and if
weather permits.
Air Cleaners
There are many types and sizes of air
cleaners on the market, ranging from relatively inexpensive
table-top models to sophisticated and expensive whole-house systems.
Some air cleaners are highly effective at particle removal, while
others, including most table-top models, are much less so. Air
cleaners are generally not designed to remove gaseous pollutants.
The effectiveness of an air cleaner
depends on how well it collects pollutants from indoor air
(expressed as a percentage efficiency rate) and how much air it
draws through the cleaning or filtering element (expressed in cubic
feet per minute). A very efficient collector with a low
air-circulation rate will not be effective, nor will a cleaner with
a high air-circulation rate but a less efficient collector. The
long-term performance of any air cleaner depends on maintaining it
according to the manufacturer's directions.
Another important factor in
determining the effectiveness of an air cleaner is the strength of
the pollutant source. Table-top air cleaners, in particular, may not
remove satisfactory amounts of pollutants from strong nearby
sources. People with a sensitivity to particular sources may find
that air cleaners are helpful only in conjunction with concerted
efforts to remove the source.
Over the past few years, there has
been some publicity suggesting that houseplants have been shown to
reduce levels of some chemicals in laboratory experiments. There is
currently no evidence, however, that a reasonable number of
houseplants remove significant quantities of pollutants in homes and
offices. Indoor houseplants should not be over-watered because
overly damp soil may promote the growth of microorganisms which can
affect allergic individuals.
At present, EPA does not recommend
using air cleaners to reduce levels of radon and its decay products.
The effectiveness of these devices is uncertain because they only
partially remove the radon decay products and do not diminish the
amount of radon entering the home. EPA plans to do additional
research on whether air cleaners are, or could become, a reliable
means of reducing the health risk from radon.
Beware of
Carbon monoxide
If you have a natural gas furnace, or
any type of fuel-burning appliance, regular professional maintenance
can literally save your life.
A properly functioning gas appliance
produces harmless water vapor and carbon dioxide, which are vented out
of the house. But if a heat exchanger is cracked, a flue pipe is
plugged or if the pilot light doesn't have an adequate amount of
oxygen, the natural gas won't combust properly, causing deadly carbon
monoxide (CO) to develop.
Symptoms of Carbon Monoxide
Poisoning
When this colorless, odorless,
tasteless gas is inhaled, it enters the bloodstream and robs blood
cells of oxygen. The symptoms of carbon monoxide poisoning mimic the
flu -nausea, headaches, dizziness, fatigue - and long-term exposure
can be fatal.
One way to check the "health" of a
natural gas appliance is to look at the color of the pilot light.
The flame should be at least 80 percent blue. If the flame is mostly
yellow, it could be producing carbon monoxide - have the unit
checked by a professional immediately. But remember that CO can be
produced even if the pilot light is blue, so invest in an annual
professional tune-up and follow the other preventive measures listed
here.
To protect your family, invest in a
high-quality carbon monoxide detector. Similar to a smoke detector,
these electronic alarms alert you to dangerous levels of CO. Carbon
monoxide is lighter than air and rises to the upper levels of your
home, so install the detector close to bedrooms and living areas.
Weatherizing your Home
 The federal
government recommends that homes be weatherized in order to reduce the
amount of energy needed for heating and cooling. While weatherization
is underway, however, steps should also be taken to minimize pollution
from sources inside the home.
In addition,
residents should be alert to the emergence of signs of inadequate
ventilation, such as stuffy air, moisture condensation on cold
surfaces, or mold and mildew growth. Additional weatherization
measures should not be undertaken until these problems have been
corrected.
Weatherization
generally does not cause indoor air problems by adding new pollutants
to the air. (There are a few exceptions, such as caulking, that can
sometimes emit pollutants.) However, measures such as installing storm
windows, weather stripping, caulking, and blown-in wall insulation can
reduce the amount of outdoor air infiltrating into a home.
Consequently, after weatherization, concentrations of indoor air
pollutants from sources inside the home can increase.
For more information Please
Contact our engineers, call at 88 00 44
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