Indoor air quality

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Many people work in an office environment. The air quality in these environments (referred to as 'Indoor Air Quality') must be maintained so as to prevent health or comfort problems. Poor indoor air quality may decrease productivity (Wyon, 2004). This article discusses the identification, investigation and management of indoor air quality problems.

Types of symptoms

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.

Causes of indoor air quality problems

Causes may include:

  1. Inadequate ventilation for the number of people occupying a building. 
  2. Chemical contaminants from indoor sources – eg volatile organic chemicals emitted from carpets or manufactured wood furnishings, pesticides, cleaning agents, unflued gas heaters or work processes producing fumes.
  3. Chemical contaminants from outdoor sources – eg air intake located near a source of vehicle exhaust fumes, cigarette smoke, plumbing vents or kitchen or bathroom exhaust air;
  4. Biological contaminants – eg 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; or
  • work overload or underload.

Resolving indoor air quality problems

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; and
  • possible contaminants and how people could be exposed.

An investigation of indoor air quality generally involves:

  1. A walkthrough inspection to gather information on the issues detailed above, inspect possible problem areas and consult with building occupants.
  2. Review of any documentation available on the above issues.
  3. Consultation with the person managing the maintenance and control of the air conditioning, heating and ventilation systems.
  4. 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, however in some cases National Environment Protection (Ambient Air Quality) Measures (NEPM) may be used as an alternative reference point (eg 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: 

  1. Increasing ventilation rates or the proportion of fresh air circulated by the ventilation system. 
  2. 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. 
  3. Providing local exhaust ventilation where there is an ongoing source of contaminants as part of a work process, e.g. printing/photocopying area.
  4. 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. 
  5. Increasing ventilation temporarily where new floor coverings, paint or furniture have been installed or pesticides used inside a building.

Preventing indoor air quality problems

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 The Use of Ventilation and Air Conditioning in Buildings and AS/NZS 3666 Air-handling and water systems of buildings. 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. Consider engaging a pest management company that provides 'integrated' pest management solutions.
  • 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.

Legislation

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), the employer has a duty of care to mitigate this hazard as far as practicable, under Section 19(1) of the Occupational Safety and Health Act 1984 ('the Act'). When an employee reports health effects which may be related to indoor air quality, the employer has an obligation under Regulation 3.1 of the Occupational Safety and Health Regulations 1996 to (as far as practicable) identify the hazard and assess the risk of harm to health. 

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 employer. The person who has control of a building used as a workplace has a duty of care under Section 22 of the Act to take practicable measures to improve the indoor air quality, so that the occupants are not exposed to a hazard. When a worker or manager in a building reports health effects have occurred, which may be related to indoor air quality, the person in control of the building has an obligation under Regulation 3.1 of the Occupational Safety and Health Regulations 1996 to (as far as practicable) identify the hazard and assess the risk of harm to health. 

Overlap of duties

Where the duties of the employer and the duties of the person in control of the building overlap, they should reach an agreement about who is to undertake the duties. If no-one undertakes the duties, both parties may be in breach of the requirements. 

Sources and further information

  • AS/NZS 3666 Air-handling and water systems of buildings (Set).
  • AS/NZS 1668 The use of Ventilation and Air-conditioning in buildings (Set).
  • US Environmental Protection Agency, Indoor Air Quality Publications, http://epa.gov/iaq/.
  • World Health Organisation, 2010. WHO Guidelines for Indoor Air Quality: Selected pollutants. 
  • Wyon, D. 2004. ‘The effects of indoor air quality on performance and productivity’. Indoor Air, vol. 14, Supp. 7, pp. 92-101. 

For further information:

  • Contact WorkSafe on 1300 3007 877. 
  • Contact an occupational hygienist. Occupational hygienists may be listed in the Yellow Pages, on-line, or via the Australian Institute of Occupational Hygienists, www.aioh.org.au.  

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