Indoor air quality

The term 'sick building syndrome' (SBS) is used where:

• building occupants report symptoms of discomfort such as headache, eye, nose or throat irritation, dry cough, dry or itchy skin, tiredness or sensitivity to odours
• the symptoms appear to be linked to the length of time people spend in a building or a particular part of the building
• the cause of the symptoms is not known.

Symptoms improve soon after leaving the building. The term 'building related illness' (BRI) is used where:

• building occupants report symptoms such as headache, eye, nose or throat irritation, cough, dry or itchy skin, tiredness, chest tightness, fever, chills or muscle aches.
• the cause of the symptoms can be identified and is related to airborne contaminants in the building. 
• symptoms may take some time to improve even after occupants have left the building.
• indoor air quality problems are likely to affect building occupants to different extents due to individual health factors and susceptibility to contaminants.

• Inadequate ventilation for the number of people occupying a building
• Chemical contaminants from indoor sources – e.g. volatile organic chemicals emitted from carpets or manufactured wood furnishings, pesticides, cleaning agents, unflued gas heaters or work processes producing fumes
• Chemical contaminants from outdoor sources – e.g. air intake located near a source of vehicle exhaust fumes, cigarette smoke, plumbing vents or kitchen or bathroom exhaust air
• Biological contaminants – e.g. mould or bacteria (which may have multiplied in damp conditions), bird droppings, dust mites, cockroach allergens, mouse droppings.

People may perceive indoor air quality problems as more serious when there are other factors reducing their comfort such as:

• hot or cold environment
• draughty or stuffy environment
• ergonomic factors such as workstation design or adjustability, lack of space or poor lighting
• noise or vibration
• nuisance odours
• work overload or underload.

Investigating and resolving indoor air quality problems can be complex, however identifying the likely cause and controlling it should minimise health and comfort concerns and maintain productivity. The building manager may choose to employ an occupational hygienist to conduct the indoor air quality investigation. The person investigating will need information on:

• the building occupants, their locations, movements, tasks, and symptoms
• the building’s air conditioning and ventilation systems
• possible contaminants and how people could be exposed.

An investigation of indoor air quality generally involves:

• a walkthrough inspection to gather information on the issues detailed above, inspect possible problem areas and consult with building occupants
• review of any documentation available on the above issues
• consultation with the person managing the maintenance and control of the air conditioning, heating and ventilation systems
• taking measurements where appropriate; for example, air movement, temperature, humidity and carbon dioxide. 

Monitoring for specific airborne contaminants is not usually helpful as they are commonly present at levels below workplace exposure standards or limits, however in some cases National Environment Protection (Ambient Air Quality) Measures (NEPM) may be used as an alternative reference point (e.g. particulates, carbon monoxide, nitrogen dioxide, ozone). 

Sampling should be conducted based on known contaminant sources; for example nitrogen dioxide and carbon monoxide would only be sampled where indoor combustion processes are present. Health or comfort symptoms are more likely to be caused by a combination of contaminants than from a high level of one specific contaminant. Carbon dioxide is the exception as it is an indicator of the adequacy of ventilation for the number of occupants in a building.

Following the investigation, the investigator may form a theory or hypothesis about the cause of the problems. This should be tested by implementing corrective actions and then carrying out further inspection and consultation to see whether the problem has resolved. If the investigator has not been able to identify a possible cause of the problem, a more detailed inspection of the building and air handling systems may be required.

Possible corrective actions may include: 

• increasing ventilation rates or the proportion of fresh air circulated by the ventilation system. 
• ensuring the air conditioning, heating and ventilation system is being operated and maintained in accordance with the manufacturer’s specifications and as far as practicable in accordance with AS/NZS 1668 The use of ventilation and air conditioning in buildings and AS/NZS 3666 Air-handling and water systems of buildings. The systems should be regularly cleaned, and records of such maintenance should be kept. 
• providing local exhaust ventilation where there is an ongoing source of contaminants as part of a work process, e.g. printing/photocopying area.
• removing pollutants – for example, removing mould-affected panels or carpets; removing mould from the ventilation system, substituting hazardous cleaning chemicals with less hazardous chemicals where practicable, a carpet cleaning regime to remove dust mites, restricting smoking around air intake points. 
• increasing ventilation temporarily where new floor coverings, paint or furniture have been installed or pesticides used inside a building.

Problems in buildings can be prevented at the design stage, including the correct location of air intakes, provision of adjustable ventilation and the availability of natural light. Low chemical emission materials should be used in construction, fit-out and furnishing. Air conditioning and air handling systems should be designed in accordance with AS/NZS 1668 and AS/NZS 3666. These standards should also be considered when buildings are renovated, which may alter the number of people occupying different areas of the building.

Preventative measures that should be taken in all workplaces include: 

• clean up all water spills immediately
• do not over-water office plants
• report any water leaks immediately
• smoke only in outdoor areas, away from air intakes and doors
• keep kitchens, including appliances, clean
• ensure perishable foods are stored correctly and disposed of if they perish
• ensure rubbish is collected regularly
• do not cover air vents or grills – if you are too hot or cold, contact the person in charge of the air conditioning system
• use non-chemical pest management techniques where possible, or ensure only low toxicity pesticides are used
• use non-chemical cleaning methods where possible
• have new furniture unwrapped and aired elsewhere prior to installation
• notify the building manager as soon as possible if an indoor air quality problem arises.

Duties of employers

Where the indoor air quality of a building used as a workplace presents a hazard (to some or all workers occupying the building, or other people accessing the building), the person conducting a business or undertaking (PCBU) has a primary duty of care to ensure, so far as is reasonably practicable, the health and safety of workers and others at the workplace.

When a worker or other person reports health effects which may be related to indoor air quality, a duty holder has an obligation to manage the risks to health and safety. Furthermore, Regulation 40 of the Work Health and Safety (General) Regulations 2022 requires a PCBU at a workplace to ensure, so far as is reasonably practicable, the ventilation enables workers to carry out work without risk to health and safety.

Duties of the person in control of the building

In some cases, aspects of indoor air quality may not be in the control of the PCBU who operates the workplace. 

Under Section 20 of the Work Health and Safety Act 2020, a person with management or control is considered a PCBU at the workplace, to the extent that their business or undertaking involves management and control of the workplace.

They have a duty of care to ensure, so far as is reasonably practicable, that anything arising from the workplace is without risk to health and safety of any person. This includes the indoor air quality at the workplace.

A person with management or control have a duty of care to ensure, so far as is reasonably practicable, that the fixtures, fittings or plant are without risks to the health and safety of any person. With regard to indoor air quality, this could include the maintenance of the heating, ventilation and air conditioning system.

Overlap of duties

Where the duties of the PCBU and the person with management or control overlap, they should reach an agreement about how to address the issue. This means that the duty to provide and maintain a safe work environment and adequate facilities may be shared between duty holders. For example, a PCBU renting their workplace will share duties with the landlord or property manager.

If no-one addresses the issue, both parties may be in breach of their duties.