Microbial Contamination and Indoor Air Quality - The Malaysia Context

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.