UNDERSTANDING MOLD
Molds are microscopic fungi, a group of organisms which
also includes mushrooms and yeasts. Fungi are highly
adapted to grow and reproduce rapidly, producing spores
and mycelia in the process.
You encounter mold every day. Foods spoil because of
mold. Leaves decay and pieces of wood lying on the
ground rot due to mold. That fuzzy black growth on wet
window sills is mold. Paper or fabrics stored in a damp
place get a musty smell that is due to the action of
molds.
Molds can be useful to people. The drug penicillin is
obtained from a specific type of mold. Some foods and
beverages are made by the actions of molds. The good
kinds of molds are selected and grown in a controlled
fashion.
Molds are undesirable when they grow where we don’t want
them, such as in homes. Over 270 species of mold have
been identified as living in Canadian homes. Molds that
grow inside may be different from the ones found
outdoors.
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Mold can be harmful or helpful — depending on where
it grows.
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Mold needs moisture to grow.
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Mold does not grow on dry materials.
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Mold growing inside a home can affect the occupants.
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Occupants can learn to recognize mold.
What makes molds grow?
Molds will grow if we provide them with moisture and
nutrients. If we keep things dry, molds do not grow.
High moisture levels can be the result of water coming
in from the outside, through the floor, walls or roof;
or from plumbing leaks; or moisture produced by the
people living in the home, through daily activities like
bathing, washing clothes or cooking. Water enters the
building when there is a weakness or failure in the
structure. Moisture accumulates within the home when
there is not enough ventilation to expel that moisture.
Different kinds of molds grow on different materials.
Certain kinds of molds like an extremely wet
environment. Other kinds of molds may be growing even if
no water can be seen. Dampness inside the material can
be enough to allow them to grow.
Why are molds a concern?
Damage to materials is one concern. Materials get
stained or discolored, and over time they are ruined.
Moldy paper and cardboard disintegrate over time.
Fabrics are damaged. Continued mold growth can be
indicative of moisture conditions favorable for growth
of fungi that cause wood rot and structural damage.
When molds are growing inside the home, there may be
health concerns. Molds release chemicals and spores.
Health experts indicate that, depending on the type of
mold present in a home, the amount and degree of
exposure, and the health condition of the occupant, the
health effects of mold can range from being
insignificant to causing allergic reactions and illness.
Pregnant women, infants, the elderly and those with
health problems, such as respiratory disease or a
weakened immune system, are more at risk when exposed to
mold. Consult your family physician if you believe there
is someone who may be at risk.
Is there a mold problem?
Molds are always found in the air outside and in all
buildings. They come into the home in many ways —
through open windows or doors, on clothing, pets, food
or furniture. The problem starts when mold grows inside
the home.
Some mold growing, for example on the window sill but
not elsewhere, is not a cause of concern. You can clean
the mold yourself. The presence of mold is a sign that
there is too much moisture in your home — a situation
which must be corrected.
Inspect the home to find the extent of the mold.
How can you tell if it is
mold?
Discoloration
Discoloration is a sign of mold. However, all
discoloration is not due to mold. Carpeting near
baseboards, for example, can be stained by outdoor
pollution entering the home. Stains or soot may also be
caused by the smoke from burning candles or cigarettes.
Mold may be any color: black, white, red, orange,
yellow, blue or violet. Dab a drop of household bleach
onto a suspected spot. If the stain loses its color or
disappears, it may be mold. If there is no change, it
probably isn't mold.
Smell/Odor
Sometimes molds are hidden and cannot be seen. A musty
or earthy smell often indicates the presence of molds.
But a smell may not be present for all molds. Even when
you don't notice a smell, wet spots, dampness or
evidence of a water leak are indications of moisture
problems and mold may follow.
When should you seek
professional help?
You may need professional help when:
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There is a lot of mold
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The home is very damp and moist
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Mold comes back after repeated cleaning
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A family member suffers from asthma or respiratory
problems or other health problems that appear to be
aggravated inside the home
How do you get professional
help?
Contact your local CMHC office for a list of individuals
who have completed the CMHC Residential Indoor Air
Quality Investigator program. A trained IAQ
investigator, who operates a private business and sells
his/her services, examines the indoor air quality of
your home and documents your concerns. He/she identifies
the problems, finds their sources and suggests solutions
in a written report. Recommendations are provided to you
in an action plan that consists of various options to
improve the indoor air quality in your home.
HOW TO CLEAN UP MOLD
PROBLEMS
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“Small areas” of mold can be
cleaned with a detergent solution.
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Wear a mask, safety goggles and rubber gloves.
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Seek professional help if there is a lot of mold or
if mold comes back after cleaning.
Bleach is NOT recommended
The presence of organic (humic) materials, the pH
(acidity/alkalinity) of the water, the surface material
and contact time affect the effectiveness of bleach for
disinfection. Since these factors are not generally
controlled, bleach cannot be relied upon for
disinfection. The most compelling reason for advising
against bleach is that fumes are harmful but in
addition, overuse of bleach will result in increased
releases of chlorinated effluents which can be harmful
to the environment.
“Small area” clean-up
You can clean up “small areas” of mold (fewer
than three patches, each smaller than a square meter)
yourself. The minimum protective wear needed are:
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safety glasses or goggles;
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a disposable dust mask (3M 8210 or equivalent); and
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household rubber gloves.
Infants and other family members with asthma, allergies
or other health problems should not be in the work area
or adjacent room during the cleaning.
Washable surfaces:
Scrub with an unscented detergent solution; then sponge
with a clean, wet rag and dry quickly.
Using an unscented detergent will make it easier for you
to detect residual moldy odors.
Moldy drywall:
Clean the surface with a damp rag using baking soda or a
bit of detergent. Do not allow the drywall to get too
wet.
Mold that comes back after cleaning is usually an
indication that a source of moisture has not been
removed. Seek professional help from a trained IAQ
investigator.
"Moderate area" clean-up
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Clean “moderate areas” of mold, but wear
proper protective equipment and follow precautions.
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Seek professional help if there is a lot of mold or
if mold comes back after cleaning.
If you follow the proper procedures and use the proper
protective equipment, you can clean up “moderate
areas” of mold. “Moderate” means more than 3
patches of mold, each smaller than one square meter, or
one or more isolated patches larger than one square
meter but smaller than 3 square meters (size of a 4 x 8
foot sheet of plywood).
Safety precautions
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Wear a disposable dust mask (for example, 3M 8210 or
equivalent), glasses or safety goggles and household
rubber gloves.
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Isolate the area to be cleaned with plastic
sheeting, taped to walls and ceiling.
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Infants and other family members suffering from
asthma, allergies or other health problems should
not be in the work area or adjacent room during the
cleaning.
A small clean up should take minutes (not hours) to
finish. When the clean up takes hours to a day to
finish, it is suggested that you upgrade to a better
filter, such as a half-face respirator with charcoal
cartridges. An exhaust fan installed in a window in the
room being cleaned would prevent contamination of other
areas of the house as well as provide ventilation.
General cleaning
Vacuum surfaces with a vacuum cleaner which has a High
Efficiency Particulate Air (HEPA)
filter or is externally exhausted. Scrub or brush the
moldy area with a mild unscented detergent solution.
Rinse by sponging with a clean, wet rag. Repeat. Dry
quickly. HEPA vacuum the surfaces that were cleaned as
well as surrounding areas.
Cleaning wood surfaces
Vacuum loose mold from wood surfaces using a HEPA or
externally exhausted vacuum. Try cleaning the surface of
the wood with detergent and water. Rinse with a clean,
damp rag and dry quickly. If the staining does not come
off, sand and vacuum the surface of the wood with a
vacuum/sander combination. It is important to vacuum at
the same time to prevent mold spores from being
dispersed into the air. Note that wood affected by rot
may need to be replaced.
Cleaning concrete surfaces
Vacuum the concrete surfaces to be cleaned with a HEPA
or externally exhausted vacuum cleaner. Clean up
surfaces with detergent and water. If the surfaces are
still visibly moldy, use TSP (trisodium phosphate).
Dissolve one cup of TSP in two gallons of warm water.
Stir for two minutes. Note: TSP must not be allowed
to come in contact with skin or eyes. Saturate the
moldy concrete surface with the TSP solution using a
sponge or rag. Keep the surface wetted for at least 15
minutes. Rinse the concrete surface twice with clean
water. Dry thoroughly, as quickly as possible.
Moldy drywall
The paper facings of gypsum wallboard (drywall) grow
mold when they get wet or repeatedly wet and don’t dry
quickly. Cleaning with water containing detergent not
only add moisture to the paper but also can eventually
damage the facing. If the mold is located only on top of
the painted surface, remove it by general cleaning. If
the mold is underneath the paint, the moldy patch and
other moldy material behind it are best cut out and the
surrounding areas also cleaned. This should be done by a
mold clean-up contractor. New materials may become moldy
if the moisture entry has not been stopped. If this is
the case, replacement of the materials should be
deferred until the source of the moisture is corrected.
The affected areas should be temporarily covered with
plastic sheeting and sealed at the edges.
3 Non-toxic Ways to Clean Mold with Natural Cleaners
Mold may be growing in your home and you don’t even know it, that’s because mold loves dark, warm, humid places to live. Your basement, kitchen and bathroom are at the most risk for mold and bacteria growth because they are in constant contact with moisture. When the conditions are right, mold can grow within 24-48 hours. Leaving mold untreated can cause respiratory illnesses as well as be a major factor for year-round allergies. This is why it is so important to kill mold at first sight.
You’ll need the following cleaning supplies:
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Hydrogen peroxide
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Scrub brush
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Rubber gloves to protect your hands
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Vinegar
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Spray bottle
1. Hydrogen Peroxide
Hydrogen peroxide is an anti-fungal, anti-viral and anti-bacterial solution that kills mold effectively on a variety of materials such as kitchen appliances, bathroom fixtures, floors and walls.
2. Vinegar
Vinegar is a mild acid which can kill 82% of mold species. (Baking soda is often used along with vinegar for killing different species of mold).
Hydrogen peroxide is an anti-fungal, anti-viral and anti-bacterial solution that kills mold effectively on a variety of materials such as kitchen appliances, bathroom fixtures, floors and walls.
3. Baking Soda
Baking soda is a mild, white mineral powder, that can be used to kill mold in your home, plus it is safe for your family and pets. Besides killing mold, it will absorb moisture to help keep mold away.
To kill mold: Add one quarter of a tablespoon of baking soda to a spray bottle of water and shake until it has dissolved. Spray the moldy area with the baking soda and water solution, then use a scrub brush to remove all the mold from the surface. Next, rinse the surface with water to remove any residual mold on the surface.
Finally, spray the area again and let the surface dry. (This will kill any left-over mold and prevent the mold from returning).
All of these solutions are great non-toxic alternatives to chemical based cleaners. Not only because they are safe to use and safe for the environment, but all of these products inexpensive and easy to find in your local store. To learn more about the basics of mold, check out this guide from EPA.gov.
DEALING WITH AN
ONGOING PROBLEM
Repair to the building
envelope is required if moisture is entering the home
from the outside. At the same time, steps should be
taken inside the home to reduce the occupants’ exposure
to mold.
Step 1 — Discard
moldy or damaged materials
Wear a dust mask and
gloves. Furnishings, such as mattresses, carpets, or
sofas that got wet or have been stored in damp
conditions should be discarded. Discard items that are
no longer needed. Use this opportunity to reduce the
amount of furnishings — this means fewer materials to
absorb moisture and grow mold. Clothes and other items
that have been cleaned should be stored in sealed
plastic bags to prevent re-contamination.
Step 2 — Vacuum
Proper vacuuming
reduces the amount of mold spores. All surfaces in the
home (floors, walls, ceilings, shelves) and non-washable
furnishings (such as sofas, chairs, etc.) must be
vacuumed thoroughly.
Step 3 — Prevent
Keep moisture
generated within the home to a minimum by
conscientiously following the prevention steps presented
in the next section.
Step 4 — Clear wet
areas
Pull carpets and
furnishings away from walls that get wet. Carpets and
under pads that are moldy should be cut out and
discarded.
Step 5 — Dry
Take steps to dry up
areas that get wet. Monitor the relative humidity of the
air. Use a portable dehumidifier, if necessary. Ensure
that the condensate drain pan of the dehumidifier is
emptied regularly.
Step 6 — Isolate
If the mold is limited
to one area, isolate the area if possible. Cover the
affected surfaces with plastic sheeting secured at the
edges with duct tape. Note that this is only a temporary
measure to minimize your exposure.
Step 7 — Clean
Healthy individuals
can regularly clean “small” and “moderate”
areas of mold, thus preventing these from getting out of
hand, by following the safety precautions and cleaning
guidelines.
Step 8 — Seek
professional help
Consider seeking
professional help from trained IAQ investigators to
identify appropriate remediation steps inside the home.
Removing large amounts of mold will require the services
of mold clean-up contractors.
PREVENTING MOLD
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Keep the home dry.
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Find and fix water leaks.
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Discard clutter and excess stored materials.
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Clean and maintain the home regularly.
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Encourage lifestyle practices that reduce moisture.
Basic steps to prevent and
reduce mold growth
Mold needs moisture to grow. Controlling the moisture
and keeping the home dry prevents the growth of mold.
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Check your home for signs of moisture and molds.
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Find out if water is coming in from the outside and
if substantial moisture is produced inside the home.
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Fix any water leaks promptly.
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Think of the different ways moisture is produced
inside the home (for example, cooking, bathing,
plant jungle). Remove the moisture as it is produced
by using exhaust fans. In the absence of fans, open
windows for a short time, but note that the wind can
push the moisture to other parts of the home.
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Measure how much moisture is in the air. To find the
relative humidity in your home, you’ll need a
hygrometer. You can buy one at a hardware store or
electronics store. A hygrometer costs from $10 to
$60. Relative humidity in the home should be under
45 per cent in the winter (or lower to avoid
condensation on windows). If necessary, use a
dehumidifier to lower the relative humidity.
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Reduce the amount of stored materials, especially
items that are no longer used. Molds grow on
fabrics, paper, wood and practically anything that
collects dust and holds moisture.
Mold-proofing your home,
room by room
Basement or crawl space
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Reduce the amount of clothes, paper and furnishings
stored in the basement. Discard badly damaged
materials. Eliminate clutter to improve air
circulation. Only washable items should be stored.
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Dehumidify the basement during the warm months.
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Avoid carpets on slab-on-grade or below grade
floors.
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Periodically clean the drain in your basement floor.
Use half a cup of bleach, let it stand for a few
minutes, then flush with plenty of water. Keep the
drain trap filled with water.
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Avoid standing water. Keep sump pits covered (you
can use plywood wrapped with plastic).
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Regularly clean and replace furnace filters. Use a
pleated one-inch filter, not a coarse filter.
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If you have a heat recovery ventilator (HRV), clean
the filter inside the HRV often.
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If you notice molds or signs of dampness, such as
water on your windows or wet spots elsewhere, do not
humidify. Disconnect furnace humidifiers that are no
longer used.
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If you have electric baseboards, vacuum the units,
or have a professional clean them for you.
Laundry areas
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Check that your clothes dryer exhausts to the
outside.
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Remove lint every time you use the dryer.
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Don’t hang-dry laundry indoors.
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Dry your laundry tub and washing machine after you
use them.
Bathrooms
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Check the bathroom fan to make sure it exhausts to
the outside.
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Turn the bathroom fan on when you shower. Keep it
running for a few minutes after you finish your
shower.
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Take short showers.
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Keep surfaces that get wet, such as the walls around
the bathtub and shower, clean and dry.
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If there is a carpet in your bathroom, remove it.
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Check for water leaks.
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Keep drains in good shape by removing debris from
them.
To clean a drain:
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Pour a handful of baking soda into it.
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Add a cup of vinegar.
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Put the plug in the drain.
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Let the vinegar and baking soda work for about 20
minutes.
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Run fresh water into the drain.
If the drain is still clogged, use a small plumbing
snake.
Kitchen
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If the fan over your stove exhausts outside, use it
when you cook.
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Minimize open boiling.
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Keep your drains in good shape. Follow the steps in
the Bathrooms section above.
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There’s a drip pan at the back of the refrigerator.
Pull the refrigerator out to clean the drip pan. At
the same time, vacuum dust from the coils at the
back of the refrigerator.
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Check under the kitchen sink to make sure there are
no leaks.
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Take out the garbage daily to prevent odors and
spoiling.
Closets and bedrooms
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Get rid of clothes and other stored items that you
don’t use. Keeping your closets and bedrooms tidy
makes it easier for air to circulate — and harder
for mold to grow.
Other parts of the home
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A dehumidifier helps to reduce moisture in the home
during the warmer months. Close the windows when the
dehumidifier is running.
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When family and friends come into the home, have
them take off their shoes.
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Vacuum often. If you are buying a vacuum cleaner,
try to get one with a HEPA filter. (See
below).
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Clean hard floors with a damp mop.
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Do not bring in furniture, clothing, books etc. that
have been stored in a moldy place into your home.
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Cut down the number of potted plants in the
house—soil is a good place for mold.
Exterior
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Regularly check the condition of the roof and
exterior finish for any places where water might
enter.
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Make sure that eaves troughs and downspouts are
connected and working properly and that they are
free of debris.
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Install downspout extensions to lead water away from
the building.
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Deal promptly with any problems that you find.
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