Introduction
Indoor Air
Quality, Sick Building Syndrome, Building Related Sickness and Environmental
Health has been associated to the dampness in buildings. Mold Outbreaks have
been common worldwide and microbial infections have been a public concern since
the 1990s. Many government agencies and voluntary bodies in America like the
Environmental Protection Agency (“EPA”), New York City Department of Health
(NYCDOH), Centre for Disease Control and Prevention (“CDC”), Institute of
Medicine (“IOM”), American Conference of Industrial Hygienists (“ACGIH”), Institute
of Inspection, Cleaning, Remediation Certification (“IICRC”), International Society of Indoor Air
Quality and Climate
(“ISIAQ”) and America Industrial Hygienists Association (“AIHA”) have published
various guidelines in Mold, Mold Prevention and Remediation. In addition, World
Health Organization (“WHO”) in Europe have published “WHO Guidelines for Indoor
Air Quality: Dampness and Mould” in 2009 in recognition for the seriousness of
Microbial Growth due to Dampness in Buildings as a public health concern
globally.
All of these agencies
and bodies regard visible indoor molds is not tolerable to the health in consensus
[1]. This view is supported by abundance of researches and scientific
publications. Visible mould was positively associated with asthma, wheeze and
allergic rhinitis. According to CDC, children in homes with visible mold are 49
percent more likely to have asthma than kids not exposed to the problem. In
addition, the risk of nasal allergies is 39 percent higher among children in the
moldy houses, too.
The
objective of this paper is to review the various guidelines from these
agencies, including the mold prevention strategies and mold remediation
cleaning procedures with consideration local climates, building materials and
practices. In addition, review will be made on the researches conducted in this
topic in Malaysia so that a more holistic review and recommendation can be made.
Climate
and Ecology in Malaysia
We
live in the tropical area with abundant of rainfall and sunshine throughout the
year. The average rain fall is as high as 2500mm per annum and the average
temperature is 27 degree Celsius. Vast variety of fauna and flora thrives in
our thick tropical rain forests. In general, the ambient humidity is high,
ranging from above 60% Relative Humidity (“RH”) [2] in the day time to approx
100% at night in the outdoor environment. The rich and moist soil in the
forests with plenty of organic food in the top soil offer heavenly conditions
for growth and it houses huge diversity of organisms, ranging from the visible
insects, termites and reptiles to the microscopic organisms which are not
visible to the naked eyes.
These
microorganisms play an important role to decompose dead plants and animals and
replenish the nutrients to the mother nature, contributing to the chemical
balance in the ecosystems.
Microorganisms are microscopic organisms and there are present naturally
in our habitats and bodies. In fact, they are used in the fermentation of
alcohol, making of cheese, production of Antibiotic, power generation (methane
gas) and water treatment. With the rapid development in genetic engineering and
biotechnology, microorganisms will continue to benefit us.
In
comparison to the hot and humid weather in the outdoor, the relative humidity
in the indoor environment ranges within 60% to 70% RH in our buildings. However, in the areas with higher dampness
like the toilets, kitchens, non-shaded external walls, on the drains and
laundry areas, the Relative Humidity is higher. Black, yellowish, green or
brown circular spots can be easily found in these places. In addition, these
circular spots can be found on leaky ceilings and they are commonly regarded
them as common and negligible” stains” in Malaysia.
Prof.
Dr. Vikineswary Sabaratnam, a prominent Microbiologist in Universiti Malaya conducted
research on these “stains” with collection of samples on the external walls
throughout Malaysia and she isolated more than 100 type of microorganisms from
the samples. These include mold, bacteria, viruses, algae, protozoa and
microscopic animals, mites and plants. Although majority of microorganisms are
harmless, some of them are health hazardous pathogens.
Indoor
Microbial Growth and Environmental Health
Despite
the diversity of the microorganisms, they germinate, replicate and thrive in
the condition as follows:
1) Humid condition, with Relative
Humidity above 70 percent adjacent to surfaces
2) Availability of food
3) Oxygen (Some microorganisms are
anaerobes)
4) Temperature (20 degree Celsius to
45 degree Celsius)
Non-
availability of any of the above conditions can prohibit the growth of
microorganisms.
Indoor
environments normally contain settled fungal spores, airborne bacteria and
other microorganisms awaiting for the hospitable condition for growth. Nutrient are readily available on the fibrous
and cellulose materials like upholstered and wooden furniture, plywood,
chipboards, MDF boards, paint, food waste, sheded skin etc.. The normal indoor
oxygen level and temperature (29 degree Celsius to 34 degree Celsius) are
rather conducive for the growth of microorganism. As a result, moisture level becomes
the determining condition in the growth of microorganisms. Thus, water damaged
buildings are associated to microbial growth with potential health risks for
infection through respiratory tracks.
As
most Malaysians spent approximately 90 percent of their time in the buildings, excessive
presence of microorganisms in the buildings lead to exposure of the occupants
to bacteria and mold level which is not tolerable to the healthy adults. Some
species of Bacteria and Mold can produce spores and/or endoscope. Beside, some
of these microorganisms produce enzymes that caused decay on the building
materials which adversely affect the structural integrity and authenticity of
the buildings. Unpleasant musty odour produced can jeopardize the comfort of
the occupant, too.
Healthy
adults have immunity that can resist pathogenic airborne microorganisms with
total bacteria count of up to 500 CFU/m3 and total fungal count of 1,000 CFU/m3,
according to the Industry Code of Practice for Indoor Air Quality 2010 in Malaysia
and America Conference of Industrial Hygienists’ Mold Guidelines. However, the
young, old, sick and pregnant have lower immunity and they are more susceptible
to the invasion of these airborne pathogens.
A
comprehensive study was conducted by the Institute of Medicine, USA in the
effect of Dampness, Microbial Growth and Health Effect. A report known as “Damp
Indoor Spaces and Health” was published in 2004. Appended hereunder is a
summary of the findings.
Evidence of Association between Damp Indoor Environments and
Mold Health Outcomes
|
||
Health outcome or
symptom
|
Exposure to damp
indoor environments
|
Presence of
mold/other agents in damp indoor environments
|
Sufficient evidence of
an association
|
||
Sufficient evidence of
an association
|
||
Asthma symptoms in
sensitized persons with asthma
|
Sufficient evidence of
an association
|
|
Studied in relation to
specific agents
|
Sufficient evidence of
an association
|
|
Respiratory illness in
otherwise healthy children
|
Limited or suggestive
evidence
|
|
Respiratory illness in
otherwise healthy adults
|
Inadequate or
insufficient evidence
|
|
Inadequate or
insufficient evidence
|
||
No specific studies
associated the condition with damp or moldy indoor spaces
|
||
Sufficient evidence of
an association
|
||
Fungus-related
illnesses in people whose immune system is severely immunocompromised5 and who have chronic obstructive pulmonary
disease (COPD)
|
Sufficient evidence of
an association
|
|
Sufficient evidence of
an association
|
||
Notes:
1.
Upper respiratory tract
symptoms include nasal congestion, rhinitis, allergic rhinitis “hay
fever", sneezing, runny or itchy nose, sinusitis and sore throat.
2.
Lower respiratory tract symptoms
include cough with or without production of phlegm, wheeze, chest tightness,
and shortness of breath.
3.
Hypersensitivity
pneumonitis is a lung disease that is the result of exposure and sensitization
to antigens inhaled with a variety of organic dusts. Symptoms include dry
cough, dyspnea, and fever and sometimes acute bronchospasm.
4.
Fungal sinusitis is
associated with molds but molds may come from the indoor or the outdoor
environment.
5.
Immunocompromised
persons are at increased risk for fungal colonization or opportunistic
infections.
o It is well established that fungal exposures
causes opportunistic cutaneous and subcutaneous fungal infections of the skin
of severely immunocompromised persons.
o Respiratory infections can result from exposure
to fungi, including Aspergillus spp. and Fusarium spp.
o Severely immunocompromised persons include
persons who undergo high-dose cancer chemotherapy, are recent recipients of a
solid-organ transplant, or are otherwise immunocompromised.
6.
Chronic pulmonary
disorders include cystic fibrosis, asthma, and COPD. Colonization and
infections result from exposure to fungi such as Aspergillus.
7.
"Sufficient
evidence of an association" means that studies show an association between
the agent and disease and chance, bias, and confounding were ruled out with
reasonable confidence.
8.
"Limited or
suggestive evidence of an association" means that evidence is suggestive
of an association between the agent and the disease but is limited because
chance, bias, and confounding cannot be ruled out with confidence.
9.
"Inadequate or
insufficient evidence to determine whether an association exists" means
that the available studies are of insufficient quality, consistency, or
statistical power to permit a conclusion regarding the presence of an
association. Alternatively, no studies exist that examine the relationship.
10. Respiratory infections, fungus-related
illnesses, and colonization with lung infection relating to specific organisms.
Source: Institute of
Medicine’s "Damp Indoor Spaces
and Health" (http://www.nap.edu/books/0309091934/html/).
There
are a few implications in this report. Firstly, damp indoor spaces attract dust
mites, termites, insects, cockroaches and rodents (rats and mice). Dust mites,
fragments and dropping from the cockroaches are highly infectious allergens
which can cause our bodies to develop allergenic reactions against them. Furthermore,
microbial growth induced by indoor dampness is associated to allergy and infection
at the respiratory tracts and skins among the people with impaired, deteriorating
or under-developed immune system. Some metabolites of the microorganism are
carcinogenic and toxic. Prolonged exposure to these metabolites can cause disordered
immune system and chronic respiratory illness. Thus, prevention of indoor
dampness is the key in maintaining Indoor Air Quality and Environmental Health
in the long run.
Airborne
Bacteria (Indoor)
Bacteria
make up the biggest biomass on earth and readily available in the soil, water
and air. Although majority of Bacteria are not hazardous and health
threatening, some of them are pathogenic and they can cause acute sicknesses.
They are group of microscopic single cell organisms
whose do not have true nucleus, or any other membrane-bound organelles.
They do have one chromosome of double-stranded DNA in a ring and they reproduce
by binary fission, a self expansion and asexual division of cell for
reproduction.
Some
scholars in local higher tertiary education centres like University Malaysia
Terrengganu have conducted some indoor air quality assessment in the university
in 2011 and found out that Legionella pneumophila is a dangerous bacterium that can be found in poorly
maintained Air Conditioner Systems and it has become main cause
of fatal Pneumonia and Moraxella Catarrhalis infection [3]. These bacteria can attach to the mist of
contaminated water and infect us at the respiratory tracts. Other genus of Legionella
can cause Pontiac fever, high fever, chill, cough, muscle pain and headache, without
pneumonia infection [4].
In addition, a study by a group of scientists in University Putra
Malaysia in five randomly selected primary schools in Malaysia in 2011 found that normal flora bacteria was the most frequently
isolated bacteria including Staphylococcus spp., Pseudomonas
spp., Bacillus spp. and Terribacillus spp.. The average
concentrations of bacteria in indoor and outdoor air were 1025 ± 612 CFU/m3
and 1473 ± 1261 CFU/m3, respectively [5]. Except Staphylococcus spp, all these bacteria are pathogenic.
In a study supported by Sweden Council for Environmental and Agriculture
Science and Spatial Planning which involve 8 secondary schools in Johore in
2010, a genus of bacteria known as Streptomyces
spp was detected in most of their samples was a risk factor for
doctor-diagnosed asthma in these schools. This bacterium causes mycetoma
(chronic subcutaneous infection) and inflammation to the respiratory tracts. In some serious cases, invasion
of Streptomyces to the bloodstream was
reported [6].
In comparison to the acceptable total bacteria count of 500 CFU/m3 in
indoor environment, bacterial infection is a common threat to the pupils in
Malaysia.
Indoor Molds
Molds are microfungi with microscopic structures. In hospitable environment
for growth, microscopic seeds like structure known as spores absorb water,
swell to 2 to 3 times their original size, and begin to form thread-like
structures known as hyphae. As hyphae grow, root like structure known as
mycelium grow and penetrate deep into the food source in search for more
nutrients. Emission of enzyme assists breaking down of organic food into simple
nutrients. A tangled mass of hyphae
visible to the unaided eye is a mycelium. When mycelium
continues to grow in all directions, a circular pattern will be formed. When
the mold mature, aerial hyphae will form and release spores in their
reproduction process.
Spores of different genera and species of mold take different duration
for germination. In general, Molds start to grow on damp spots with hospitable
environment if the dampness last for more than 24 hours.
Many molds that thrive in damp indoor environments produce Mycotoxin and
Microbial Volatile Organic Compounds (“mVOC”) which is linked to moldy musty
odour. Some of these mycotoxin and mVOCs are carcinogenic and/or toxic. In
poorly ventilated indoor environments, the concentration of these toxins in the
indoor air increase overtime, causing the consequential drop in Indoor Air
Quality. Inhalation of these toxins can cause toxic effects ranging from short-term
irritation to immunosuppression, severe dermatosis on the skins and cancer [7].
In addition, inhalation of
excessive spores and mold fragments can cause the immune systems to overreact
to these allergens. This reaction triggers a cascade of reactions that lead to
allergy symptoms. Like other allergies, a mold allergy can make you cough, make
your eyes itch and cause other symptoms that make you miserable. In some
people, mold allergy is linked to asthma and exposure causes restricted
breathing and other airway symptoms. Continuous exposure to these biology
pollutants like bacteria and mold spores, fragments and metabolites (Mycotoxin
and mVOCs) can cause weakening in the immune systems due to the toxic effects
and development of allergy, resulting in opportunistic infections.
There are numerous guidelines of biological pollutants in USA and
Europe. Amongst the most hazardous indoor molds that give rise to public health
concern in these countries include Strachybotrys
Chartarum, Aspergillus Versicolor, Penicilium, Chactomium, Trichoderma, Phoma,
Fusarium, Trichothecenes, A. Flavus, A.
Fumigatus, Fusarium Moniliforme and Histoplasma Capsulatum. Upon verification with
Prof. Dr.
Vikineswary Sabaratnam of Universiti Malaya, all these molds are present in
Malaysia.
In the study conducted by a group of scientists in University Putra
Malaysia in 5 primary schools in 2011, the most frequently isolated fungal
genera in these primary schools were Aspergillus, Penicillium, Fusarium, Rhizopus
and Zygomycetes with
the average concentration of fungal bioaerosol in indoor and outdoor air were
292 ± 83 CFU/m3 and 401 ± 235 CFU/m3. All these molds are
pathogenic parasites.
In the research by the Swedish scientists that targeted the study of the
association of Asthma to fungal DNA, allergens and mycotoxins in secondary
school in Johore conducted in the year 2011, scientists found fungi level were
high enough and mycotoxins have been detected in up to 22 percent of classes
involved in the study. The total fungal DNA levels were 50 times higher than a
Swedish day-care centre study, using the same sampling method conducted in
Sweden. This is attributed by the hot and humid climate conditions in Malaysia
which is conducive for microbial growth. It was concluded that fungal DNA and
cat allergens were common in the studied Malaysian schools and there was high
prevalence of both doctor diagnosed asthma and respiratory symptoms among the
students.
Prevention of Microbial
Growth - Moisture Control
The climates, buildings
and men form a microecology where they interact with each other within the
buildings. For instance, climate influence the Relative Humidity in the indoor
environment and we design our buildings to create a hospitable environment with
comfortable humidity level and shelter us from the rain and ground water.
Nevertheless, our activities like breathing, cooking, washing and showering
increase the Indoor Relative Humidity. Vapor produced by our activities is
vented through the windows or driven out of the buildings by mechanical means
like the exhaust fans. Waste water is channeled to the drainage system and
dampproofing system installed prevents water seepage to the floor and soaking
of water to the wall via capillary suction.
Rain
Penetration and Ground Water
The hot and humid
climate with an average rainfall of 2,500mm per annum, high Relative Humidity
and vast coverage of forest and landscaped areas posses a big challenge in
Moisture Control and Mold Prevention in Malaysia. The increase in rainfall,
thunder storms and floods recently has been observed due to the green house
effect globally. As a result, Rain Water and Ground Water has become a major
concern in the Moisture Control in Malaysia.
The mechanism which
prevents rain penetration include the roof system, gutters, flashings, rain
water down pipes and the drainage system. The gradient on the slope varies
according to the roof system employed. On flat concrete roof, the deterioration
of waterproofing membranes, construction joints and expansion joints is caused
by ultra violet, thermal pressure difference and movement due to settlement,
wind load and mechanical parts installed (i.e. water tanks, cooling towers and
gondolas). In addition, poor maintenance and cleaning on the flat roof like
debris causes water collection and blockage can expedite the deterioration due
to permeation of water, build up of acidity in the concrete and concrete damage
due to swelling of reinforcement steel bars due to oxidization. Indeed, they need
regular replacement and maintenance in order to upkeep the functionality and
performance. On average, these systems require replacement every 10 years.
Besides, sloppy ground
with gradient that drain rain water away from the building (i.e. 5% steepness,
6” per 10 ft) is vital to prevent capillary suction of rain water through the
foundation and the floor. Waterproofing at the foundation, vapor diffusion
retardants below the concrete floor slab and dampproof course on the first
layer of bricks are important mechanism to prevent vapor diffusion via
capillary suction of the ground water. If the steepness of the earth cannot be altered
for proper drainage due to unforeseeable limitation, installation of
underground subsoil system can assist prevention of ground water intrusion to
the buildings.
Building Construction
Authority (“BCA”) in Singapore conducted a survey involving about 10,000
private residential units and found almost 90 percent of water seepage came
from the cracks in the plastered external walls. Being a maintenance
contractor, the author has evidenced many incidence of this nature in the building
in Malaysia. BCA outlines many good industry practices in construction
including waterproofing of external perimeter walls and planters, dampproof
course, proper method in brick laying and plastering, material handling, installation
of mess reinforcement at the bricks and edges, application of sealant and the
treatment at joints between dissimilar materials. Although these recommendations
are not compulsory in Malaysia, it is good measures that we should consider in
improving the construction quality.
Water
Consumption and Discharge
Plumbing system
requires regular maintenance, too. Steel pipes prone to rust and leak due to
the exposure to chlorine in the domestic water. Other piping and sealing
materials like PVC, ABS and PE also have an average life of 15 years.
Waterproofing system in
the areas with regular wetting and water consumption must be installed
according to the systems outlined below. Construction of 25mm X 25mm of angle
fillets, application of highly elastic and adhesive waterproofing compound,
cement rendering and installation of tiles with the desired gradient (i.e., 1”
drop per 10’) must be installed to prevent seepage of waste water via gravity
and capillary suction to the adjacent walls. Such system is applicable to the
toilets, laundry and kitchen in the ground floor.
Building
Materials
Hygroscopic materials
and soft wood used in the building also is prone to microbial growth. These
products include the fabrics, plywood, chipboards, MDF boards, timber floor,
carpet, lumber for roofs and furniture.
The moisture content in these materials is above 10 percent. If coupled
by a low level of dampness, say 65 percent RH, the air adjacent to these
surfaces will reach dew points at the lower temperature at night and they
become hospitable to microbial growth.
Vapor
Diffusion
The hot and humid
climate causes vapor diffusion into the building due to the higher vapor
pressure in the outdoor environment. Therefore, vapor diffusion retardant is
important to prevent such high inward flow of moisture. In areas with low
latitude, sealer and coating system on the external walls is commonly adopted
due to the ease of application and low costs.
Vapor is also produced
during our breathing and daily activities like showering, washing, combustion,
cloth drying and cooking. In addition, ornament water features, aquariums,
plants and pets contribute to the increase in indoor humidity, too. Ventilation
of the vapor produced is vented outdoor with exhaust fans, cooking hoods,
vented roof systems and ventilators.
Condensation
Vapor in the air condense
to water when the air can no longer withhold the water in the air when it
encounter a surface with a low enough temperature. Condensation of the vapor
causes wetting of the surfaces which promote microbial growth.
Due to the hot climate
in Malaysia, adoption of air conditioners is common. In residential buildings,
split unit air-conditioners are most common. In fully air conditioned
residential buildings with fully sealed openings and no dehumidification,
moisture control become a big challenge. Although the RH of the chilled air is
lower, vapor can diffuse inward from the high RH outdoor air due to
non-availability of vapor diffusion retardant, cavity, unplanned openings and
excessive ventilation. In addition, non-availability of dehumidified fresh air supply
can elevate indoor moisture due to our normal activities, too. Thus, the humid
air will condense when it encounters the cold indoor surfaces caused by the air
conditioning.
Oversizing and prolong
use of air conditioners causes cooling of walls that extends to the external
surfaces, depending on the conductivity of the materials used in the
construction of the wall and the availability of insulation. Condensation
occurs on the external wall when the cold wall surfaces encounter humid
external air. In the rigorous environment in the hospitals and cleanrooms, foam
or glass wool insulation is needed in preventing condensation.
Sufficient insulation
must be installed on the copper tubes for the coolant that connect the indoor blower
and the external condenser. Leaking caused by condensation can be evidenced due
to insufficient insulation and the wrapping at the joints of the insulation
tubes. Double insulation without tightening at the joint of the insulation
tubes is recommended.
In commercial building which
is air tight with comprehensive and planned mechanical ventilation and cooling
system, dehumidifier is integrated in the air handling and fresh air supply system.
Positive air pressure relative to the external air is maintained in order to
prevent intrusion of humid external air. Air ducts must be sealed with mastic
in order to prevent air leakage. In addition, the duct must be covered by
sufficient insulation, i.e. foam or glass wool and covered by aluminium foil as
vapor diffusion retardant.
Condensation water
produced in the cooling system must be effectively drained away with the dripping
pan and the piping. This drainage system must be cleaned and maintained
regularly in order to prevent any blockage which will cause build-up of
stagnant water, hence promoting microbial growth.
The bacteria known as Legionella pneumophila has been
identified widely and its growth in the old cooling towers with corrosion and
metal sediment in the hot and humid climate [8]. Water treatment and regular
monitoring and cleaning of the water quality in the Cooling towers is necessary
to prevent the build-up of biofilm amd Legionnaire disease. Routine screening,
although not mandatory, is recommended to monitor the Legionella. The American
Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE)
will release ASHRAE
Standard 188: Prevention of Legionellosis Associated with Building Water
Systems in summer 2012. This standard outlines the proactive
preventive measure and the procedures in annual water monitoring, risks
analysis, disinfection and recovery plan in the event of Legionnaire outbreak in
air conditioning systems and water systems [9].
Myths in Controlling
Biological Contamination and Deodorization
There are a few common myths
related to the control and clean-up of biological contamination and
deodorization in Malaysia. These are quick fixes that do not address the
underlying problem in moisture intrusion that lead the microbial growth. In
many instances, these quick fixes create other corresponding adverse side
effects when the symptoms of the contamination are covered up.
Ultraviolet
Germicidal Irradiation
Ultra Violet Germicidal
Irradiation (“UVGI”) that uses low pressure mercury lamp to produce Ultraviolet
C (“UVC”) with wavelength of 200nm to 300nm. They are installed in the ducting system
or in the portable air cleaners.
UVGI can disrupt the
DNA of the microorganisms and render them inactive and harmless to us.
Nevertheless, the effectiveness in disinfection depend on the duration of
exposure to the radiation, susceptibility of the ultra violet inactivation of
different microorganism and their spores (bacterial and fungal spores are the
most resistant to UVGI), dust coverage on the UVGI lamps, ability of
microorganism to repair their damaged DNA and wear and tear of the UVGI lamps [10].
Ozone gas, an air pollutant, is produced when UVC hits oxygen gas. Besides, the
inherent risks of leakage of UVC which is a low penetrating form of UV compared
to Ultraviolet A and Ultraviolet B can be detrimental to our eyes. It can cause
inflammation to the cornea and retina, including blindness, if not shielded
properly. The exposure of skins to the UVC which is mutagenic and carcinogenic
can cause skin aging and skin cancer, in some rigorous cases. Since UVC is
invisible light, its leakage can hardly be identified [11].
Ozone
Cleaners
Ozone comprises of
three oxygen atom with unstable molecular bonds and is a strong oxidation agent.
Some vendors claim that ozone generators which are sold as Air Cleaner can
clean the air via oxidation of organic pollutants including biological
contaminants like the bacteria and molds. They also claim that these ozone
generators are safe for use and capable of controlling indoor air pollution.
Nevertheless, such claim has been refuted by medical professionals [12].
Concentration of Ozone
gas is safe at 0.05ppm. At this level, it has been scientifically proven that
it takes too long for the reaction of the oxidation cleaning. Secondly, for many of the chemicals with which ozone does
readily react, the reaction can form a variety of harmful or irritating
by-products [13].
Ionizers
Ionizers which
is also known as “Electronic Air Cleaners”, are devices that disperses
negatively (and/or positively) charged ions into the air. These ions attach to
particles in the air giving them a negative (or positive) charge so that the
particles may attach to nearby surfaces such as walls or furniture, or attach
to one another and settle out of the air. In recent experiments, ionizers were
found to be less effective in removing particles of dust, tobacco smoke, pollen
or fungal spores than either high efficiency particle filters or electrostatic
precipitators [14].
Photo
Catalytic Oxidation
Photo catalytic
oxidation (“PCO”) is another oxidization agent which is claimed to be stronger
than Ozone Gas in controlling indoor pollutants including microorganisms. Recently,
EPA has funded the research and scientifically proven that application of PCO is
limited because currently available catalysts are ineffective in destroying
gaseous pollutants from indoor air. In addition, oxidation of some chemicals
available in indoor environment can produce more harmful by-products that
worsen the indoor air quality [15].
Air
Filtration
Air filtration in
residential and commercial buildings is designed for entrapment of particulate
dusts. Depending on the blowing load and filtration efficiency of the filters
adopted, the filtration of large particulate dusts can be ineffective for larges
dusts which will settle from the air quicker on the ground before it reaches
the filters. In rigorous environment with high expectation for cleanliness,
High Efficiency Particulate Air (“HEPA”) filters and strong blowing fans are
adopted.
In addition, air
filtration cannot remove contaminating gases like the mycotoxin and mVOCs produced
by molds and bacteria [16]
Air
Duct Cleaning
According to EPA, air
duct cleaning has never been showed to prevent health problems. Air duct
cleaning is only needed in the event of identification of visible molds inside
the ducts or on other component in the air conditioning system, clogging caused
by excessive deposition of dusts and/or infestation of vermin (rodents and
insects). Normal settled dusts and spores are not harmful.
EPA emphasizes on the
importance of settling the underlying problems of these problems before any air
duct cleaning. Otherwise, these problems will recur. Indeed, air duct cleaning
alone produce limited effect in the improvement of indoor air quality. More emphasis
should be given to prevention of the dirt and water from entering the air ducts.
Although there is no detrimental effect for engaging air duct cleaning,
professionalism and comprehensive cleaning in all air conditioning components is
needed for a thorough servicing [17].
Perfume
Spay
Perfume sprays are
widely installed in the offices in order to give some pleasant scent and combat
musty odor. Nevertheless, little has been known about the deterioration to the
indoor air quality.
Researchers concluded
that Perfume-scented strips can
cause exacerbations of symptoms and airway obstruction in asthmatic patients. Severe and atopic asthma increases risk of
adverse respiratory reactions to perfumes [18]. In some cases, an excessive use of perfumes may cause allergic reactions of the skin. For instance, acetophenone, ethyl acetate and acetone while present in many perfumes, are also known or potential
respiratory allergens [19].
Bacteria
and Mold Disinfectants
Bacteria and Mold Disinfectant
can effectively kill and remove these microorganisms. However, dead mold
fragments and spores are equally allergenic, be it alive or dead. Furthermore,
biocides and antimicrobials can be harmful to humans, pet and wildlife if not
used properly. These chemicals should only be used to treat microorganisms on
the surfaces and structures and in the manner for which the products have been
registered by appropriate government agencies.
Anti
Microbial Coatings
Anti Microbial Coatings
which integrate Nano Silver and other innovative disinfectant chemicals can
hardly be applied to some concealed areas that microorganisms grow, i.e. internal
part of Gypsum Board Partitions and Insulation, air ducts and wooden roof
trusses. These coatings should not be adopted with the tolerance to moisture
control.
Cleanliness
on the External Walls
Mold grows on the
external walls is an indication of a reservoir of microorganisms in close
proximity. Water seepage on cracks and
cavities on the external give rise to the dampness that is hospitable to
microbial growth. Water seepage and air leak in the cavities can bring in the
spores and fragments of microorganisms and increase the microbial concentration
indoor. The normal breath of wind at 15 to 20 knot can effectively carry the
spores into the buildings via the doors, window and other openings.
Decontamination of
Microbial Outbreak
Decontamination
exercise has been recommended by all the renowned agencies in environmental
health and industrial hygiene, including EPA, AIHA, ACGIH, IICRC, NYCDOH,
Canada Health Department and ISIAQ. Moisture control and physical removal of
visible molds with proper containment, personal protection equipment and
disposal of contaminated materials is vital in reducing the contamination,
avoiding cross contamination and protecting the workers and occupants.
AIHA has reviewed 7
voluntary remediation guidelines of the above mentioned agencies and 4 mold
remediation and assessment documents in its recent publication known as
“Recognition, Evaluation and Control of Indoor Mold”. Several principles in
mold assessment are common in these guidelines and document as outlined below:
1. Mold
growth (colonization) should not be tolerated on indoor materials and
furnishing
2. Initial
assessment and evaluation should include a thorough visual inspection
3. The
extend of mold growth and water damage should be visually assessed
4. Intrusive
method of assessment such as use of a borescope or creating openings into
closed cavity is necessary to inspect hidden mold
Common principles in
remediation of indoor mold include:
1. Moldy
building materials and content should be cleaned and discarded
2. Remediation
work should be conducted in a manner that limit the mold be aerosolized and
limit aerosolized materials in the workplace
3. The
type of containment should be guided by how much building materials/ content is
impacted
4. The
remediation areas should be clean and free from visible mold and debris
5. Small
areas of mold can be addressed by building maintenance and engineering staffs
6. Professional
judgment should be utilized when there is more than a small area of
contamination
Common principles in
worker health and safety measures include:
1.
Personal Protection Equipment in the
form of respiratory protection, gloves and eye protection is recommended
2.
Any worker expected to perform
remediation work of any size should receive training commensurate to the extend
of the expected work to be performed [16]
Amongst the abundant
guidelines and document in mold assessment and remediation, the document
published by the IICRC has been accepted by the America National Standard
Institute (“ANSI”) as the national standard, namely ANSI/IICRC S520 Standard
and Reference Guide for Professional Mold Remediation.
In the event of
microbial outbreak, investigators must be protected with sufficient Personal
Protection Equipment (“PPE”) in view of the inherent risks of such outbreak. Knowledge
in Building Science, Thermodynamics, Materials Science and Medicine is vital in
order to earn preliminary understanding of building damage, epidemic response among
the occupants and the subsequent remediation plan. In some complicated cases,
experts from other disciplines will be invited for a professional diagnosis and
planning of procedure and extent of remediation.
Occupant of the
affected buildings will be interviewed according to questionnaires. Indoor Air
Quality Assessment which involved air sampling and isolation of microorganism
is needed in the ambiguous situation.
Diagnostic tool involve
in ascertaining the vapor intrusion and generation are appended hereunder:
1.
Thermo-hygrometer – a device that
measures the temperature and ambient RH
2.
Moisture Meter – a probe that measure
moisture level on the substrates
3.
Psychrometric chart – a chart to
determine the Dew Point Condition
4.
Manometer – an instrument to measure the
static air pressure differential between two or more adjacent areas
5.
Thermal Imaging Device – an instrument
used to detect surface temperature differences and do not detect moisture or
measure moisture through materials
6.
Borescope – An optical device allow
remote viewing into concealed areas, such as wall cavities, air ducts and the
hidden compartment of utilities
7.
Data Loggers – this is chart recorders
that measure and record atmospheric conditions over time
Other
more advance equipment and non-destructive testing for complicated cases
include:
1.
Pressure Gauge Testing – a device to
check the domestic water pipes
2.
Echo inspection – an instrument to
inspect hidden utilities and cavity
3.
ASTM D5957 - 98(2005) Standard Guide for
Flood Testing Horizontal Waterproofing Installations
4.
ASTM C1060 - 11a Standard Practice for
Thermographic Inspection of Insulation Installations in Envelope Cavities of
Frame Buildings
5.
Ultrasonic Leak Detector – A device that
detect underground pipe leaking
6.
Blower Door Test – A analytical system
for assessment of air leak in the ducting system
After the initial
inspection is completed, the next step involves developing a preliminary
determination that draw a conclusion on the identification of actual or
potential mold growth, known or suspected areas of moisture intrusion and the
need for the involvement of other experts or health care professionals.
The investigators need
to determine the risk level and a formal assessment of Condition 1, 2 or 3 as
follows:
Condition 1 (normal
fungal ecology): an indoor environment that may have settled spores, fungal
fragments or traces of actual growth who identity, location and quantity are
reflective of a normal fungal ecology for a similar indoor environment
Condition 2 (settle
spores): an indoor environment that is primarily contaminated with settled
spores that were dispersed directly or indirectly from a Condition 3 area, and
which may have traces of actual growth
Condition 3 (actual
growth): an indoor environment contaminated with the presence of actual mold
growth and associated spores. Actual growth includes growth that is active or
dormant, visible or hidden.
Upon the determination
of the type of Condition and the risk assessment, the investigator can develop
work plans, protocols ad specification. Consideration in such remediation
procedures include containment, pressure differentials, hazardous or regulated
materials, safety and health provisions, contents, contamination materials
removal and handling, detail cleaning, disposal, post remediation evaluation,
post remediation evaluation and containment removal.
These plans must be
communicated to the customers and building occupants before the execution of
work. In addition, workers involved must go through medical surveillance
check-up before commencing the work. Then, occupants will respiratory illness
and mold allergy must be isolated during the course of work.
Remediation commence
with the briefing and training to the workers involved with regards to the use
of PPE and the scope of work. Then, containment is erected according to the
specification and negative air exhaust fans with HEPA filters are installed. Leaking
and moisture intrusion must be stopped first. Materials exposed to microbial
growth are cleaned with HEPA Vacuum and damp wiping, sanding and scrapping is
done, depending on the type of surfaces. Porous materials are physically
dismantled, packed with double disposal bags and duly labeled as dangerous hazardous
waste. For porous materials with visible mold that need to be preserved,
special preservative cleaning and drying is recommended. The debris will then be
delivered to designated disposal sites or processed by designated waste
management contractors [20].
In the hot and humid
climate in Malaysia, dehumidification with the use of dehumidifiers is
critical. Steam cleaning is not recommended due to the excessive humidity
released. Use of Disinfectant is not necessary except in the outbreak caused by
Bacteria and Viruses. Antimicrobial coatings and sealant can be adopted without
the compromise to moisture control. Duct cleaning is no recommended except in
the event of identification of visible molds in the ducting and air
conditioning systems.
Post
remediation Evaluation
Evaluation with Laser
Particulate Counters, air sampling and thermal graphic imagers is used after
the remediation work. Unless and until the evaluation indicates successful result,
the containments will not be taken down and disposed.
Conclusion and
Recommendation
The hot and humid
climate in Malaysia is indeed a heaven for microorganisms. Any moisture
intrusion can easily give rise to microbial growth. Although limited, the
scientific publications available in Malaysia with regards to microbial
contamination indicates that bacteria and molds are common in Malaysia.
Nevertheless, the knowledge of the health impact of such contamination is very
low among the Malaysian communities.
The research in the
indoor fungi, identification of specific pathogen and the consequential impact
of the metabolites to the environmental health is still in infant stage. More
research is needed while moisture intrusion and microbial outbreak is on the rising
trend in Malaysia nowadays.
Statutory requirement relating
to microbial growth and exposure limit is available for commercial and
industrial buildings only. There is no guideline for residential buildings in
Malaysia to-date. Nevertheless, we can adopt guidelines and recommendations
from other international bodies with established guidelines and standards. The
challenge lies on adopting these guidelines with the consideration in local
environment.
Amidst of the gimmicks
promoted by various vendors in improving indoor air quality, we must take more
scientific measures in this aspect and adopt a systematic approach to prevent
indoor microbial contamination by ensuring dryness, cleanliness and hygiene for
our buildings and the occupants. Indeed, moisture control is the only measure
and it is predominantly an engineering concern. In the event of microbial contamination,
decontamination is the only effective mean to remove and control the contamination.
In conclusion, the
construction design, construction quality control and routine maintenance is
the bottom line for moisture control and prevention of microbial contamination.
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16. Ditto.
Pg 6 to 7.
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