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Information Bulletin: Workplace Health and Safety Guideline - Legionella

  • Issued: October 2005
  • Content last reviewed: July 2019

The public health system has primary responsibility for the health of members of the public, including residents of long-term care facilities, patients of hospitals, and occupants of public buildings such as offices serving the public. For further details contact your local municipal public health unit.

The Ministry of Labour enforces the Occupational Health and Safety Act and its regulations, which set legal requirements for employers to ensure protection of workers.

Legal Requirements:

Employers have a duty under the Occupational Health and Safety Act, section 25(1)(a) & (b), to ensure that equipment, materials and protective devices that they provide are maintained in good condition. Section 25(2)(h), requires the employer to take every precaution reasonable in the circumstances for the protection of a worker. This includes the maintenance of water systems and ventilation systems in buildings to protect workers from the hazard of Legionella exposure.

Regulations also have provisions for protection of workers from hazards such as Legionella. The Regulation for Health Care and Residential Facilities, section 8, requires that the employer implement measures and procedures for worker health and safety. Pursuant to section 9, this may include the proper use, maintenance and operation of equipment. Section 19 of the Health Care and Residential Facilities Regulation requires that indoor ventilation be adequate to protect the health and safety of workers and a mechanical ventilation system be inspected by a qualified person every six months to ensure it is in good condition. It also requires the ventilation system to be serviced and maintained as prescribed. The Regulation for Industrial Establishments, section 127, requires industrial establishments to be adequately ventilated such that the atmosphere does not endanger the health and safety of workers.

Workplace parties such as employers, supervisors and workers share the responsibility for occupational health and safety under the internal responsibility system. If the internal responsibility system fails to address adequately the health and safety issues in a workplace, or if the Occupational Health and Safety Act and regulations are not being followed, the Ministry of Labour has the authority to enforce the law.

There was an outbreakof legionnaires disease linked to a long-term care home in Toronto in September 2005 affecting residents, staff and visitors. Workers and residents were affected. The Ministry of Labour is releasing this information bulletin to remind employers of their obligations to protect the health and safety of workers, provide information about legionnaires' disease and re-affirm expectations of employers and workers.

It is the responsibility of employers to be knowledgeable about the hazards caused by Legionella bacteria and to put in place necessary precautions to protect workers. Legionnaires' disease is a form of pneumonia caused by Legionella bacteria. Legionnaires' disease is most often contracted by breathing in contaminated mist from warm water sources. Sources of appropriate prevention measures for Legionella contamination and workplace hazards are noted in the websites below.

Legionnaires' disease has an incubation period (the time from exposure to the onset of symptoms) of two to 10 days. Symptoms of legionnaires' disease include fever, chills and a cough. For more information regarding the symptoms of legionnaires' disease, please visit the Public Health Agency of Canada website.

Employers must ensure that appropriate preventive maintenance programs are in place to prevent workplace health hazards arising from Legionella bacteria. In the event contamination takes place resulting in a hazard to workers, remediation strategies and worker protection measures must be implemented. For technical assistance and guidance contact the Health and Safety Association for your sector.

The following websites are not endorsed by the Ministry of Labour but provide guidance on Legionella contamination prevention and remediation.

Canadian Centre for Occupational Health and Safety (CCOHS)

U.S. Department of Labour--Occupational Safety and Health Administration (an OSHA eTool with information about the disease itself, potential sources of the bacterium, outbreak investigation protocols, and outbreak response)

Centers for Disease Control and Prevention (CDC)

Control of Legionellosis — Health and Safety Executive, United Kingdom

Public Health Ontario – Legionella Questions and Answers

Infrastructure Health and Safety Association – Legionellosis Cause and Controls