Air Conditioning & Legionnaires Disease

Many workers spend long periods of time indoors, in air-conditioned buildings. If the air-conditioning system is not maintained, a number of problems, some potentially lethal, can occur. OHS reps have a role to play in ensuring that risks associated with air-conditioning are identified and reduced as much as possible.

Action Plan for the Health and Safety Representative

As with all workplace hazards, the hazard should be dealt with in this way

  1. Identification of the hazard
  2. Assessment of the risk
  3. Elimination or reduction of the risk
  4. Review and evaluation of any control strategies.
  • Talk to members of your work group - ask co-workers whether they are experiencing problems with air-conditioning at work. Consider doing a questionnaire. Circulate the air-conditioning questionnaire which can be downloaded here.
  • Inspect the workplace: including the air outlets in the ceiling. Are they dirty?
  • Inspect the air-conditioning maintenance records to discover when the system was last inspected and cleaned.
  • Place thermometers and hygrometers around the workplace to measure temperature and humidity.

For more information on the hazard, see below.


In assessing the severity of the problem, consider the following:

  • Temperature: The acceptable zone of thermal comfort for most kinds of work lies between 16° - 26°C. (18° - 24°C for offices, shops, showrooms, canteens, dining rooms - depending on the outside temperature; as low as 13°C for heavy work in factories)
  • Humidity: 40-50%.
  • Air Movement: 2 - 4 metres per second.
  • Minimum Fresh Air Rate: Offices require 10 litres of fresh air per person per second (computer rooms 25 litres, cafeterias 15 litres).
  • Oxygen Content: 18-21%.
  • Carbon Dioxide: Limited of 1,000 parts per million.
  • Microrganism Level: Less than 1,000 colony-forming units per cubic metre.
  • Inspection of Air Intakes and Exhaust Outlets: At least annually.
  • Cleaning and Replacement of Air Filters: In accordance with manufacturer's specifications.
  • Inspection of Humidifiers and Evaporative Coolers: At least monthly.
  • Inspection of Ductwork: Annually.
  • Inspection & testing of Cooling Tower/s: At least monthly.
  • Cleaning of Cooling Tower: Every three to six months or according to the Risk Management Plan (see Hazard Sheet on Legionnaires Disease).

Warning: If any of your members have flu-like symptoms and you discover the air-conditioning system has not been cleaned for some time, call your Union and the Department of Health and Human Services on 1300 253 942 (free call in Victoria except with mobile phones) or email: [email protected] immediately. Contact details for regional offices on this page.


Reducing the risks associated with the air-conditioning system should involve:

  1. Providing all information you have gathered under Steps One and Two to the employer representative and your co-workers.
  2. In consultation with the union delegate, arranging a meeting with management to discuss the problems you have identified and agree on a control plan.
  3. If you cannot agree on action, then reporting this back to the members. The next step may be to serve a PIN or raise the issue at the Health and Safety Committee. You may also contact a WorkSafe inspector for advice.
  4. If you have reached agreement, setting a time frame for each action item to occur.

The fourth step is to review the success of the actions taken to fix the air-conditioning problems. This may involve discussions with management and members and a follow up questionnaire survey might be helpful. Consider negotiating an Air-conditioning Policy with your employer. Contact your union to see if they have a model policy.

The employer has a duty under the Victorian Occupational Health and Safety Act (2004) to provide and maintain for employees, as far as practicable, a working environment that is safe and without risks to health. This includes providing safe plane, a safe system of work, information, training, supervision, and where appropriate personal protective equipment. The employer also has the duty to monitor conditions at the workplace, and to monitor the health and safety of employees.

There is a range of Victorian regulations that specifically seeks to limit the occurrence of Legionnaire's Disease. This follows the occurrence of a large number of cases of Legionnaires Disease due to contaminated air-conditioning units. On 1 January 2010 the  Public Health and Wellbeing Regulations 2009 came into effect.  Included in these regulations are important changes concerning the regulation of cooling towers and warm water systems for the control of Legionella.  (Check this Fact sheet page for information on these regulations) These replaced the original regulations which were introduced when there was that outbreak of legionella at the new Aquarium.  See the Hazard Information page for more detailed information.

The Problem

A building's air-conditioning system can be described as the lungs of the building. The air-conditioning system draws in outside air, filters it, heats, cools or humidifies it, circulates it around the building, then expels a portion of it to the outside environment.

An air-conditioning system is made up of intake ducts, air filters, cooling tower/s, a boiler and exhaust ducts.

The quality of the air many workers breathe at work is totally dependent on the operation of the building's air-conditioning system. Substandard air-conditioning will lead to poor indoor air quality irritable and potentially very sick workers.

The cost of poor air-conditioning at work is enormous. Studies show that increased sick leave and lower productivity related to poor air-conditioning, costs many millions of dollars each year. The human costs of poor air-conditioning include viral illness, respiratory problems, and deadly Legionnaires Disease (or Legionella).

What are the health effects of poor Air Conditioning systems?

Often the cause of respiratory and nasal symptoms is not properly diagnosed; therefore the work related nature is not recognised. There are three major categories of health problems:

  1. Lungs and respiratory tract problems
    E.g. runny nose, blocked nose, coughing, sore throat, sneezing.
  2. Virus and bacteria reactions
    E.g. fever, chills, headaches, muscular ache, nausea and vomiting. Diseases include influenza, bronchitis and Legionnaire's Disease (see Hazard page on Legionnaire's Disease).
  3. Allergic reactions
    E.g. itchy nose, watering eyes, shortness of breath, wheezing and coughs. Illnesses include sinusitis, asthma and humidifier fever.

Who is at risk?

Large numbers of workers are at risk:

  • workers in air-conditioned buildings, including office staff, cleaning staff and security staff
  • staff in air-conditioned venues such as hotels, museums, aquariums, gaming venues
  • building maintenance workers (such as mechanics, electricians, etc)
  • air-conditioning company workers


Last amended November 2016