A living organism, mould is present almost everywhere and its microscopic spores are easily spread through the air.
Mould growth can increasingly damage building structures, possessions and endanger people’s well-being. In some cases, particularly in residential instances, mould has even made the building uninhabitable.
Although there are hundreds of references about the causes of mould in buildings, there are two main contributing factors in mould development: moisture and darkness. In other words, high humidity and insufficient brightness in buildings are the most important triggers of mould problems in indoor environments. Let’s look at the major causes of mould growth.
EXCESS MOISTURE
In a report in 2009, the World Health Organisation stated that the growth of microbes such as mould, fungi and bacteria is caused by excess moisture in the building elements that will pollute indoor air quality. Humidity level can increase by both direct and indirect reasons:
- Direct moisture problems may include a leaky roof, broken pipes, water vapour condensation on windows, humidifiers in buildings, drying clothes indoors on stands and running appliances without an exhaust.
- Indirect damp rise can be caused by poor ventilation – basically, inadequate ventilation does not allow humidity to escape from the building. This can be caused by malfunctioning HVAC, poor design of the building, or an influx of cheap materials with high water vapour storage capacity used in the building structure.
LACK OF LIGHT
Mould grows best where there are small amounts of light or curtains and blinds are kept shut. According to the Black Mould Control website, large quantities of light, and in particular ultraviolet light, break up and destroy the DNA of mould, resulting in the sterilisation of the mould.
EFFECTS OF MOULD ON HEALTH
A study published in the Journal of Occupational and Environmental Medicine states, “Except for persons with severely impaired immune systems, indoor mould is not a source of fungal infections”, while the US Occupational Safety and Health Administration website has also cited that mould may cause localised skin or mucosal infections but, in general, does not cause systemic infections in humans, except for persons with impaired immunity, AIDS, uncontrolled diabetes or those taking immune suppressive drugs.
Having said that, findings from the US Environmental Energy Technologies Division claim that building mould is associated with increases of 30 to 50 percent in a variety of respiratory and asthma-related health outcomes.
Generally, allergy and irritation are the most common symptoms of mould exposure. Less common effects of mould exposure include infections and illness. Although symptoms can vary, researchers in the Division of Environmental Health Sciences of the University of Minnesota believe that the most common symptoms seen in people exposed to mould indoors include:
- nasal and sinus congestion
- eye irritation, such as itchy ,red, watery eyes
- wheezing and difficulty breathing
- cough
- throat irritation
- skin irritation, such as a rash
- headache, and
- risk of lower respiratory illness.
ERADICATION OF MOULD
In order to eliminate mould from a building, there are some essential steps to be taken:
Maintaining and monitoring the HVAC system
The HVAC system has an important part to play in promoting mould growth. Highly commissioned or maintained ventilation systems will leave no room for mould to grow. Always attempt to keep the HVAC/air conveyance system, air-handling units, exhaust outlets and air filters clean, dry and serviced regularly, and changed according to their maintenance schedule, enhancing the quality of indoor air.
If mould is evident, the HVAC system needs to be isolated to ensure airborne spores do not spread into the entire building. Once the HVAC system has been decontaminated, it can be turned back on.
The American Air and Water Company has developed aUVdisinfectionsolution,whichcanbeusedinHVAC systemstoirradiatethecoilsanddrippingpans.This newsystembenefitsfrommixingtwomainresolutions: reducinghumidityandprovidingUV(ultraviolet)light. Thisisaneffectivesolutionformouldinhibitionand remediation.Withinstalledin-ductUVC,itwilleventually deliverenoughUVdosagetobreaktheDNAoftheairborne mouldsporesandhasacumulativeeffectonthecirculation of indoor air throughout HVAC systems.
Ongoing monitoring humidity level in building
According to the US Environmental Protection Agency, indoor relative humidity (RH) should ideally be kept between 30 and 50 percent to avoid mould growth. Keep humidity levels low, always below 60 percent, in the building – anything above that will exponentially allow mould colonisation. HVAC systems can be equipped with moisture sensors and can provide facility managers with accurate indications of humidity level in building management systems.
Moisture source elimination
The source of any dampness needs to be remedied immediately. In high-rise buildings, leaky fire-protection sprinklers, rainwater leaks and leaky landscaping on top floors are some examples of dampness sources that promptly need to be repaired. Also, waterproofing balconies is one of the most significant preventative steps to discourage mould growth.
Raising resident awareness
Try to encourage residents and occupants to turn on exhaust fans, particularly when bathing, cooking, doing laundry or drying clothes. Educating residents about limiting the use of humidifiers, fish tanks and indoor plants can also reduce the risk of mould growth in apartments.
MOULD REMOVAL
Generally, surface mould, such as that found on bathroom tiles or on the surface of kitchen cabinets, can be cleaned up fairly easily without calling in outside help. However, it is still highly recommended that a facemask, safety goggles and gloves should be used in any mould cleaning.
If mould covers a large area of your building – according to the Australian Mould Guideline, this is roughly defined as one square metre – and is dense, or if occupants are asthmatic and/ or allergic to mould, it’s best to call in the experts. Professional mould cleaners should be certified, have the right equipment andspecialtraining.
One of the common professional resolutions is fogging. This is a chemical cleaning process designed to eliminate invisible airborne mould spores. This solution can be misted into large enclosed spaces (even covering inaccessible sections). Air purifiers are usually applied after this process to remove the dead mould spores from the environment.
Arian Bahramsari is a facility manager at Docklands-based Facility Management Victoria.
This article also appears in the October/November issue of Facility Management magazine.
