Indoor air quality or IAQ refers to the quality if air within an ‘indoor space’. This indoor space could be a home, office, commercial building, car, boat or submarine – in all these places people breathe air that is significantly affected by the surfaces that surround them and the air that is supplied to them. If, for a number of reasons, these surfaces or air-delivery systems are releasing chemicals, biological components or other contaminants e.g. dusts or fibres these pollutants become concentrated and may affect the health of the people in the space. The main reason for suspecting a problem with the indoor air quality of a space is that a person experiences health symptoms in one place that get better when they leave .

Indoor environments can be very complex and often contain a wide variety of contaminants. A substance can only cause health affects if it comes in to contact with the human body through one or more of the four recognised pathways – inhalation, ingestion, absorption and / or injection; exposure through inhalation of a substance is the most common and therefore gases and particulates (dusts / fibres) are the most important indoor pollutants to understand.

Typical sources include:

  • Carpets and furnishings
  • Cleaning products
  • Perfumes / cigarette smoke
  • Water damaged building materials – chemicals released, mould, bacteria
  • Insects – including dust and mould mites, cockroaches
  • Outdoor pollutants concentrating indoors

Common pollutants include:

  • Formaldehyde and other volatile organic compounds from glues, carpets, paints, insulation materials etc.
  • Carbon monoxide from incomplete combustion of gases and fuels
  • Mould / bacteria
  • Dander from pets, insects, rodents
  • Ozone from large photocopying machines
  • Cleaning chemicals including deodorisers and maintenance treatments

  • Where possible open windows or doors or use an air-conditioning / ventilation system to bring unpolluted, fresh outdoor air inside
  • Ensure that ‘cleaning’ activities remove dusts, animal dander etc. they don’t just ‘visually enhance’ the area.
  • Address any maintenance issue promptly – especially where moisture is affecting building materials and / or furnishings.
  • Investigate and address any unexplained odour, taste or change in relative humidity.
  • Ensure smoke, rubbish odours, wash room exhaust etc. cannot enter the building through windows, doors or ventilation system intakes.
  • Install well maintained indoor plants such as Spider plant, Snake plant, Golden Pothus or Bamboo – these plants filter common volatile organic compounds from the air.

The term Sick Building Syndrome, is used to describe situations in which building occupants experience acute negative physical and mental effects that appear to be linked to time spent in a contaminated area when no specific illness or cause can be identified.

People in sick buildings often complain of symptoms such as headaches, skin, eyes, nose or throat irritations, nose bleeds, dizziness, nausea, difficulty in concentrating along with physical and mental fatigue.

The reason the home or building may be suspected is that most people report relief soon after leaving the infected home/building.

Although not all the reasons for sick building syndrome are known, it is typically assumed that the negative health effects could be caused by inadequate ventilation, chemical contaminants from indoor or outdoor sources, and/or biological contaminants. Many volatile organic compounds, which are considered chemical contaminants, can cause acute effects on the occupants of a building. Bacteria, moulds, pollen, and viruses are types of biological contaminants” and can all contribute to ‘Sick Building Syndrome’.

  • Moulds are microscopic members of the fungus family. Other types of fungi include mushrooms, mildew and yeasts.
  • They are found everywherein our environment, both indoors and outdoors.
  • They play an important role in our outdoor environment, helping to decompose organic matter such as leaves and wood.
  • As mould grows it produces:
    • Mycelia, which are complex structures that can become visible to the human eye.
    • Spores, which are like seeds that can travel through the air to be deposited elsewhere.
  • The spores regularly enter the home in many ways:
    • through open windows or doors
    • on clothing
    • pets
    • food
    • furniture

  • Two conditions are essential for mould to grow: moisture and food
  • Certain types of moulds require an extremely wet environment, while others can grow with far less moisture.
  • Moisture can be the result of a number of problems, including:
    • Water coming in from the outside (failure in the roof, walls, or floor)
    • Plumbing leaks
    • Normal daily activities in the home which use water such as bathing, washing clothes or cooking.
    • Condensation on or within walls or floors due to drafts or improperly installed insulation.
  • Depending on the circumstances, mould can become established in as little as 48 hours.

  • Most types of moulds encountered in homes and buildings are not a health concern for healthy individuals.
  • Some health effects have been shown to be caused by mould; others are more difficult to prove.
  • Health effects depend on:
    • the type of mould
    • the amount of mould
    • the production of certain substances by the mould
    • the levle of exposure
    • the health condition of the person exposed
  • Some people may be more at risk of having health effects when exposed to mould:
    • pregnant women
    • infants
    • the elderly
    • those with health problems such as respiratory disease or a weakened immune system

  • Allergies to mould may develop in up to 5% of the population. In sensitive individuals, allergic symptoms can include:
    • sneezing
    • runny nose, congestion
    • red, watery eyes
    • skin rash
    • increase in asthma symptoms (for those already suffering from asthma)
  • Mould exposure can also irritate the eyes, skin, nose, throat, and lungs, without triggering allergies.
  • Allergies and irritation symptoms will disappear once the individual (or the mould) is removed from that environment.
  • Certain types of moulds can cause minor skin infections such as athlete’s foot or jock itch. In rare circumstances, mould can cause more severe infections in people who have weakened immune systems. However, these health effects are typically not associated with mould growth in homes.
  • Consult your family doctor if you believe there is someone who may be suffering from adverse health effects due to mould.

While we cannot eliminate mould in our environments, there are a number of basic steps you can take to prevent mould growth indoors.

  • Check your home and office regularly for signs of moisture and moulds.
  • Fix any water leaks, moisture or condensation problems promptly.
  • If water gets inside, dry the area as soon as possible (within 48 hours to prevent mould growth).
  • Ensure sufficient ventilation is in use in rooms where moisture is generated such as bathrooms or kitchens. Exhaust fans and clothes dryers should exhaust to the outside of the building.
  • If necessary, use a dehumidifier to lower the relative humidity (below 60%, ideally 35-55%).
  • Reduce the amount of stored materials, especially items that are no longer used. Moulds grow on fabrics, paper, wood and practically anything that collects dust and holds moisture.

Generally, it is not necessary to identify the species of mould growing in a home or office. Current evidence indicates that allergies are the type of diseases most often associated with moulds. Since the susceptibility of individuals can vary greatly either because of the amount or type of mould, sampling and culturing are not reliable in determining your health risk. If you are susceptible to mould and mould is seen or smelled, there is a potential health risk; therefore, no matter what type of mould is present, you should arrange for it to be removed. Furthermore, reliable sampling for mould can be expensive, and standards for judging what is and what is not an acceptable or tolerable quantity of mould have not been established

The size of the affected area will determine whether you should clean and remediate the area yourself or call a contractor for professional help.

  • Small areas that are no more than one square meter in overall size. This project can be undertaken by you or your maintenance team if they are comfortable to complete the work and follow proper procedures.
  • Large areas that are greater than one square meter in size. The Health Department recommends a professional contractor, experienced in mould cleaning and remediation, be used to remove the mould and water damaged building materials. The contractor should ensure that their work practices prevent cross-contamination to the unaffected parts of the building, and that the health of both the contractors and any building occupant is protected.

Cleaning and removing of mould may increase the amount of spores or other substances in the air, and expose you to direct skin contact with mould. Hence, the following items should be considered to protect yourself when cleaning mould:

  • Wear a disposable particulate respirator (for example, 3M 8210 or equivalent P2-level respirator), unvented safety goggles and household rubber gloves.
  • Isolation of the area to be cleaned is usually not necessary for small areas. However, such measures should be considered if sensitive individuals live or are near the affected area.
  • Isolation measures include closing of doors and taping the seams, or using plastic sheeting taped to walls and ceiling.
  • 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.
  • An exhaust fan blowing out of a window in the room being cleaned to the outside will help prevent contamination of other areas of the house as well as provide ventilation.
  • Any item that cannot be wiped clean should be thrown away or taken to a specialist restorer for cleaning.

In all cases, the first step in dealing with mould growth is to find the source of the moisture and remove it. If the mould returns after cleaning, then the source of the moisture is likely still there.

Cleaning and remediation procedures may be complicated or require special equipment. If you are uncertain about your ability to complete the task safely, you should engage and experienced contractor.

Ensure your health is protected by wearing a disposable particulate respirator (for example, 3M 8210 or equivalent P2-level respirator), unvented safety goggles and household rubber gloves.

  • Washable surfaces, such as tile or glass
    • Vacuum the affected surfaces as well as surrounding surfaces with a HEPA (high-efficiency particulate air) vacuum cleaner to remove any loose mould – this will reduce the amount of mould that requires cleaning.
    • Wipe or scrub surfaces using a damp (not wet) microfibre cloth and a solution of water and unscented detergent
    • Sponge with a clean damp microfibre cloth
    • Dry quickly and thoroughly with a clean dry microfibre cloth
  • Gyprock
    • Vacuum with a HEPA vacuum cleaner
    • If the mould is on the surface of the paint, wipe the surface using a damp microfibre cloth and a solution of 20% water and 80% naturally brewed white vinegar
    • Dry quickly and thoroughly with a clean dry microfibre cloth
    • If the mould is beneath the surface of the paper covering, then it is best to replace the affected gyprock – ensure that the mould does not cross-contaminate the surrounding area when it is removed (vacuum with a HEPA vacuum cleaner prior to removal; remove gently; wrap in plastic before carrying through the building for disposal)
  • Carpets, fabrics and furniture
    • It may be possible to remove surface contamination from these materials (when dry) using a HEPA vacuum
    • Professional drying and cleaning may be required
    • Remove and dispose of these items if they cannot be effectively cleaned
  • Any material or item that cannot be effectively cleaned should be sealed in plastic and disposed of.
  • Following clean-up, seal and dispose of the contents of the HEPA vacuum and clean the washable parts of the vacuum.

The Residential Tenancies Act 1997 sets out the Standard Residential Tenancy Terms (SRTT) which apply to all tenancy arrangements regardless of whether they are included in the written agreement or not. The SRTT give the tenant and the landlord certain rights and obligations.

Tenants’ rights:

  • To have a property that is fit to live in, reasonably clean and in a reasonable state of repair [cl 54]
  • To have repairs done in a timely manner [cl 57, 59]


Landlords’ rights:

  • To have the property kept in a reasonable state of cleanliness [cl 63]
  • To be advised of maintenance requirements and allowed access to the property (with reasonable notice) to make inspection and affect repairs. [cl 63, 55]


The tenant’s obligations:

  • To take reasonable care of your property and keep it reasonably clean [cl 63],
  • Report any damage and need for repairs to the lessor as soon as possible [cl 63, 55]
  • When you leave you must leave the premises in substantially the same state of cleanliness and condition, except for any fair wear and tear[cl 64]

The landlord’s obligations:

  • To provide the premises in a reasonable state when you start to live there, including that it is fit for habitation, reasonably clean and in a reasonable state of repair. [cl 54]
  • To maintain the premises in a reasonable state of repair throughout the tenancy having regard to the condition it was in when you started to live there.
  • To make non-urgent repairs within 4 weeks and urgent repairs as soon as necessary with regard to the nature of the problem. [cl 57, 59]

The tenant and the landlord both have responsibility when it comes to preventing and dealing with mould. The tenant should take steps to prevent mould from occurring and spreading if it is reasonable for them to do so or if the mould was caused by them.  For example if there is an extractor fan in the bathroom, the tenant should use it when showering.

The landlord has an obligation to ensure that the property is not in a state that would allow mould to grow, that the causes of any mould are dealt with quickly and any damage cause by mould is repaired as soon as possible. This would be the case where the cause of the mould is something a tenant cannot control such as a structural problem. Examples of this would be where the property has rising damp, or there is no extractor fan in the bathroom.

The easiest way to deal with mould is to try and prevent it forming in the first place:

Some simple ideas include:

  • Use the extractor fan when cooking, showering and doing laundry
  • Leave your curtains/blinds open so the rooms gets some sunlight during the day
  • Ensure that you use your heating as efficiently as possible, by closing curtains/blinds at night
  • Dry clothing outside if possible and don’t put them away until completely dry
  • If you notice condensation forming on walls or the ceiling, wipe it down, dry the area thoroughly
  • Open a window or door (if the weather is appropriate),
  • Leave the internal doors open to allow air circulation through the property

If you notice mould growth you should:

  • Remove all your furniture and other items away from the area if you can e.g. take clothes out of cupboards/drawers, pull furniture away from walls to allow the air to circulate
  • Dispose of any items affected by mould immediately or carefully clean and dry them.
  • Find the source of moisture that is enabling the mould to grow and permanently fix it.
  • Remove/clean mould from affected areas yourself if it is reasonable for you to do so or engage an experience contractor to remove the water damaged area and remediate the mould growth.

Under Occupational Health and Safety legislation an employer has an obligation to ensure the workplace does not expose employees to health or safety hazards.

If you believe you are ill because of exposure to mould in the building where you work, you should consult your doctor to determine the appropriate action to take to protect your health and notify your employer about your concern so that they can take action to investigate the cause, address the problem and prevent future mould growth.

The unpleasant odours are a combination of alcohol, ketones and aldehydes produces by bacteria, fungi and biofilm accumulating and growing within the coils, barrel fan, damp filters, ducts and other components of the air-conditioning system. In severe cases involving water cooled systems Legionnaires disease many be encountered. If you have unpleasant odours coming from your air-conditioning system it is a sign that it is potentially contaminated and requires specialist cleaning.

Mould requires moisture, an organic food source and time to grow. Within the air conditioning system (barrel fan, directional fins, duct, cooling / heating coils) dust and debris can accumulate and provide ample food source for mould to grow. Due to the extremely cold temperature of the air coming off the cooling coils moisture will accumulate and condense and the combination of moisture and organic food source will result in mould growing. Irrespective of whether it is significant amounts of dirt or mould that you can see, the air-conditioner requires cleaning.