When we wheeze, sneeze, cough, contract fever or
inflammation due to unknown sources of germs, do we think about where these
irritants or germs come from? Historically, the doctors have been focusing on
the sources from our body contact, foods, drink and biological response of our
bodies. Little has been known in the passage of germs through our environment
via inhalation. This can be caused by the limited knowledge in the huge diversity of microorganisms,
their metabolites and mixture of other chemicals or pollutants that exists in
the air that we inhale.
Indeed, we eat approx 1 kg of foods, drink 2 kg of
drink and inhale 10 kg of air everyday.
In other words, we inhale approximately 10,000 liter of air daily. Thus,
the pollution in the environment around us poses a serious threat that we normally
overlook. In reality, a huge diversity of germs, pollutants and irritants can
enter our bodies easily to our respiratory tracts via inhalation.
The hot and humid climate in Malaysia, coupled by
the rich soil and vast vegetation, provides heavenly condition to foster the proliferation of microorganisms. They comprise of the biggest biomass in the tropical rain
forest and play an important role in decomposing organic wastes and recycling
nutrients to nurture the soil. The nutrients are then absorbed by the plants for
continuous vegetative growth and support other wildlife.
Microorganisms exist naturally in our environment
including the air. They include airborne bacteria, viruses, molds, the spores
of bacteria and molds, and their fragments. They also exist on our skins and
some of them play an important in keeping the cleanliness and hygiene of our
bodies. Although not all microorganisms are pathogens that cause sickness,
their excessive existence in the indoor environment is associated to threaten
our health directly. Healthy adults have the immune systems to combat these
pathogens. Nevertheless, children, pregnant women, the elderly, the sick and
the immunosuppressed patients are more susceptible to the invasion of these
microorganisms.
Excessive existence of microorganisms in indoor
spaces is associated to the dampness in the buildings. This can be linked to
the factors of growth of microorganisms whereby they need air, food, humidity
and the correct temperature to grow, thrive and multiple. Of all these factors,
air, foods in the dusts and building materials, and the comfortable thermal
environment for our daily activities in the indoor environment are all
hospitable enough to support the microbial growth. Moisture control is the
variable factor in prevention microbial growth in the indoor environment.
Due to the visibility of molds as compared to the
viruses, bacteria and other microorganisms, molds have become an indicator for
microbial growth.
In the late 1990s and early 2000s, there have been
reported death cases caused by “Toxic Black Molds”, the deadly Legionnaire
Disease and the rapid surge of allergic and asthma cases globally. Scientists
in the developed countries like the USA and Europe have looked into the impact
of Damp Indoor Environment to the Environmental Health and Indoor Air Quality.
Although researches are still on-going, it has been concluded that microbial
growth in indoor environment is associated to Sick Building Syndrome, Building
Related Illnesses and development of allergy and asthma that impair the quality
of life of the occupants.
A number of voluntary guidelines have been issued to
facilitate the building related professionals and health professionals by
agencies and bodies related to industrial hygiene and public health. These
bodies include Centre of Disease Control and Prevention (USA), Environmental
Protection Agencies (USA), Health Canada, Institute of Medicine (USA), American
Conference of Industrial Hygienists (USA), Institute of Inspection, Cleaning,
Remediation Certification (USA), International Society of Indoor Air Quality
(USA) and America Industrial Hygienists Association (USA) and New York City
Department of Health (USA). In view of the seriousness of such issue as a global
public health concern, the World Health Organization has issued “WHO Guidelines
for Indoor Air Quality: Dampness and Mould” in 2009. These agencies have a view
in common; visible molds are not tolerable for public health concern.
There are more than 1,500 published research papers
and scientific publications about how molds and other indoor airborne pathogens
can bring about illness and allergy to us. However, the most profound and
comprehensive research was conducted by Institute of Medicine (USA) with a
publication of “Damp Indoor Spaces and Health” in 2004. The report indicated
that damp indoor spaces do not only attract microbial growth, it also induces
the growth of allergens like the dust mites, rodents (mites and rats), termites,
cockroaches and vermin. In addition, sufficient evidence of an association
between Damp Indoor Environments and Mold Health Outcomes in the illnesses as
follows:
- Upper Respiratory Tract Symptoms like
Nasal Congestion, Rhinitis, Allergic Rhinitis “Hay Fever”, Sneezing, Runny or
Itchy Noses, Sinusitis and Sore Throat
- Lower Respiratory Tract Symptoms include
cough with or without phlegm, wheeze, chest tightness and shortness of breath
- Asthma symptoms in sensitized persons
with Asthma
- Hypersensitivity Pneumonitis in
susceptible persons
- Severe Respiratory Infection in people
whose immune system is severly immunocompromised
- Fungus-related illnesses in people whose
immune system is severely immunocompromised and who have chronic obstructive
pulmonary disease (COPD)
- Colonization and potential lung
infection in people with some chronic pulmonary disorders
Besides, there is suggestive association of the Damp
Indoor Space and Respiratory Illness in otherwise healthy children. This view
coincides to the study conducted by Centre of Disease Control and Prevention
(USA) whereby children in homes with visible mold are 49 percent more likely to
have asthma than kids not exposed to the problems. In addition, the risk of
nasal allergies is 39 percent higher among children in moldy houses, too.
There have been mold outbreaks reported in Malaysia
in the hospitals, universities as well as commercial buildings in Malaysia.Tremendous attention was given to the safety of indoor air during the outbreak of SARS and H1N1 recently. The attention has been extended to the Malaysian scholars and scientists as evidenced by the several
researches conducted in mold contamination in the local tertiary education
centres recently. In July 2005, the Department of
Occupational Safety and Health launched a Code of Practice in Indoor Air
Quality. The acceptable limits for Biological contaminants are included in the
latest Industry Code of Practice on Indoor Air Quality 2010. These acceptable
limits are 500 cfu/m3 for total bacterial counts and 1,000 cfu/m3 for total
fungal counts.
A comparative study conducted across continents in 2007 to
2009 showed that the common indoor molds in hotel rooms in the tropical areas
may have 10 to 100 times higher compared to those in the temperate climate
zone. In a study that involved 8 secondary schools and 32 classrooms in Johore
in 2010, the mold level in these classrooms was 50 time higher than the day
care centre in Sweden, using the same sampling and analysis methods. In 2011, a
research conducted by University Putra Malaysia in five randomly selected
primary schools indicated the average concentration of bacteria in the
classrooms with natural ventilation were 1025 ± 612 cfu/m3, an unsafe level as
compared to the acceptable limit mentioned in the Industry Code of Practice on
Indoor Air Quality. In 2005, seroprevalence studies for the Legionella bacteria
was conducted in water samples collected from randomly selected cooling towers
in Malaysia. The study revealed that Legionella bacteria can be found in 75
percent of samples. Although there was
no report death caused by Legionella, substantial population is exposed to
these bacteria and sporadic infections have been reported.
The high level of microbial concentration in
the indoor environment in Malaysia in general poses serious threat to the occupants as the
most commonly found bacteria and molds are pathogenic. In addition, many molds
that thrive in the indoor environment are potent mycotoxins producers. For instance, Aspergillus and Penicilium
can be commonly found in indoor environment in Malaysia. Some genera of these molds
produce mycotoxins which are mutagenic, toxic and carcinogenic (cause cancer). Stachybotrys Chartarum, commonly known
as the “toxic black mold” produces toxic mycotoxins and microbial Volatile
Organic Compounds that can lead to chronic respiratory illness and toxicity
including pulmonary hemosiderosis and proinflammatory cytokines.
Colonization of microorganisms in the indoor
environment in Malaysia is associated to the hot and humid climate. High
humidity level is associated to the regular rain with average annual rain fall
of above 2,500mm and high level of humidity between 60 percent to 100 percent in the outdoor environment. As a result, water intrusion caused by rain water and ground
water is pervasive. Secondly, due to the hot climate, buildings are built with
air tight design and vented by mechanical cooling and ventilation systems. Nevertheless,
poor ventilation, wear and tear, human activities and condensation due to
insulation failure have been evidenced in causing elevated indoor humidity in
these buildings. Poor maintenance in the air filtration system, blocked dripping pan in
cooling coils, leaky air ducts and cooling towers with bio films have been repeatedly reported to
cause elevated humidity and microbial contamination.
There are three key strategies in prevention of
indoor molds, namely
- Source Control
- Dilution
- Dehumidification
Source Control by means of engineering methods is
the most effective and cost saving in long run. Appended hereunder are some
common methods
- Roof system with damp proofing, sealants,
flashing, gutters and drainage that channel rain wate
- Damp proofing system in toilets,
kitchen, laundry areas with sewerage pipe systems to channel used domestic water
- Exhaust fans in toilets and kitchen to
vent out moist air
- Positive air pressurization in air tight
buildings prevents intrusion of uncontrolled external moist air
- Dripping and drainage pans in air
conditioning systems
- Local exhaust ventilation for plants that remove combustion gases or vapor
- Rectification, maintenance and
replacement of the above mentioned system in the event of wear and tear
Dilution by mean of fresh air supply and mechanical
ventilation increase the air exchange in the buildings. However, the success of
dilution depends on the weather condition and the quality of external air because
air pollution depends on the locations, industrial activities and vegetation
around the buildings. Subject to the type of pollutants, air cleaning,
dehumidification and filtration may be necessary before it is supplied to the
buildings.
Dehumidification is a mechanical means of removing
water vapor in the air. This is the last option in the event that Source
Control and Dilution produces limited result in controlling ambient humidity.
Dehumidifier must be run continuously and the power consumption is a recurring
cost to the building owners.
Many gimmicks in air cleaning have been marketed to
the end users. In 2009, Environmental Protection Agency, USA (“EPA”) conducted
comprehensive studies and published a guide in residential air cleaner to clear
the doubt commonly found in the general public in relation to the effectiveness
and risks of various air cleaning technologies. In general, air cleaning
without Source Control, Ventilation and Dehumidification is ineffective in
reducing air pollution. The risks and limitation of the cleaning system must be
studied before adoption in the buildings.
Most mechanical air filters can capture large
particulates like pollens, dusts, dust mites, cockroach allergens, some molds and
animal dander. However, these particulates settle quickly before they can be
captured in the filters. Small particulates can be effectively captured by High
Efficiency Particulate Air (HEPA) filters or filters with MERV ratings from 7
to 13. The effectiveness of the air filtration depends on the regular
replacement or servicing of the filters which can be a recurring financial burden.
They cannot remove gaseous pollutants like Volatile Organic Compounds,
formaldehyde, etc in the contaminated air.
Ultra Violet Germicidal Irradiation (“UVGI”) adopts air
sanitization with the use of Ultraviolet C (“UVC”). It can disrupt the DNA of
the microorganisms and render them inactive and harmless to us. Its
effectiveness depends on the exposure of the microorganism to the irradiation,
susceptibility of the ultra violet inactivation of different microorganisms and
their spores (fungal spores are the most resistant to UVGI), dust coverage on
the UVGI lamps, the ability of the microorganism to repair their damaged DNA
and the wear and tear of the UVGI lamps. Being a low penetrating radiation, it
can cause damage to our eyes, expedited skin aging and skin cancer if not
shielding properly and leak to the environment. Besides, it also produces ozone
gas which irritates the lungs and triggers asthma attack amongst asthmatic patients.
Ozone cleaners are sold as air cleaner because Ozone
Gas is a strong oxidation agent. It is claimed that Ozone Gas oxidizes organic
pollutants and decomposes to other forms which are harmless. However, ozone at
ground level is a lung irritant and air pollutant. The acceptable limit of
concentration is 0.05ppm. At this level, it has been scientifically proven that
it takes too long for the reaction of the oxidation cleaning. Furthermore, for
many of the chemicals with which Ozone does readily react, the reaction can
form a variety of harmful or irritating by-products.
Ionizers which are also known as
“Electronic Air Cleaners”, are devices that disperse 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.
Photo catalytic oxidation (“PCO”) is another
oxidization agent which is claimed to be stronger than Ozone Gas in controlling
indoor pollutants including microorganisms. EPA found 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.
Air duct cleaning has never been scientifically
proven to improve indoor air quality, according to EPA. Normal settlement of
dusts and spores in the air ducts is harmless. Indeed, air duct cleaning is
needed in the event of excessive dust clogging, identification of visible molds
and infestation of vermin.
Perfume sprays are widely installed in the offices
to combat musty odor with “pleasant scent”. Little has been known about the
impact of such perfume in the deterioration of indoor air quality. Researchers
concluded that perfume-scented strips can cause exacerbations of symptoms and
air way obstruction in asthmatic patients. Excessive use of perfume has been
known to cause skin and respiratory allergy.
Anti Microbial Coating may help in controlling
colonization of microorganisms after the adoption of Source Control,
Ventilation and Dehumidification strategies. However, colonization in the
hidden areas without the application of the anti bacteria coating will persist
should humidity is not controlled. Use of anti microbial coating is subject to stringent regulations by the Authorities. The use of Nano Silver is common but it has received tremendous attention recently due to the potential damage to the environment, especially to the aquas livings.
Some building cleaners clean or disinfect the moldy
surfaces continuously in order to remove the visible molds. In some cases, the
author evidenced painting of moldy surfaces with paint as a mean to “cover up”
the microbial growth. However, the molds will return within 48 hours, if the
dampness persists. Killing and removal of molds with detergent or disinfectant without
moisture control render limited improvement in indoor air quality in long run
as dead mold fragments and spores are equally allergenic. Cleaning is also
ineffective in removing the hidden molds at inaccessible areas.
In the event of Mold Outbreak, a preliminary
physical inspection is needed to assess the seriousness in contamination and
extend of the remediation work. Use of professional diagnostic tool like
Infrared Thermographic Imager, Borescopes, Moisture Meters, Manometers and
Humidity Meters are needed to identify the source of water infiltration. In addition, knowledge in Non-Destructive Testing methods like ASTM D5957-98(2005), ASTM C1060 and ASTM F2170 (2011) are useful in determining the sources and level of moisture in different components in the buildings. A
thorough themodynamic study will be conducted to evaluate Air Flow, Heat Flow
and Moisture Flow. Depending on professional judgment, decontamination process which
involves erection of containment and Negative Air Pressure Exhaust Fan with
integrated HEPA filters in order to prevent cross contamination to other areas.
The adoption of protection of workers with proper Personal Protection Equipment
is vital to protect the workers and other professionals who involved in the
work. Firstly, the water infiltration must be controlled and stopped. Then, moldy
surfaces will be cleaned by vacuum cleaning with HEPA filters. Then, the
irrecoverable porous materials will be packed, labeled and physically removed
to a designated disposal site. Materials with hard surfaces will be damp wiped
and/or disinfected. Lastly, the contaminated site will be dehumidified,
evaluated before the containment is removed and the spaces restored for normal
activities.
In conclusion, microbial contamination is pervasive
although majority of us are unaware of or overlook its seriousness. Continuous
efforts are needed to create such awareness and more mandatory guidelines are
needed in enforcing and maintaining sound indoor air quality as a public health
concern. There is no quick fix and gimmicks in sound Indoor Air Quality and Mold Prevention. Indeed, Moisture Control via sound building design, construction quality and maintenance
practices are the key in moisture control and prevention of microbial contamination.
