Identification and Assessment of the Risk

Regulations

Control of Substances Hazardous to Health and Safety Regulations 199, regulation 6; Management of Health and Safety at Work Regulations 1999, regulation 3; Health and Safety at Work etc. Act 1974, sections 2, 3 and 4.

Acop

A suitable and sufficient assessment is required to identify and assess the risk of exposure to legionella bacteria from work activities and water systems on the premises and any necessary precautionary measures. The assessment is carried out by or on behalf of: the employer, where the risk from their undertaking is to their employees or to others; or a self-employed person, where there is a risk from their undertaking to themselves or to others; or the person who is in control of premises or system in connection with work where the risk is present from systems in the building (e.g. where a building is let to tenants but the landlord retains responsibility for its maintenance).

In conducting the assessment, the person on whom the statutory duty falls is required to have access to competent help to assess the risks of exposure to legionella bacteria in the water systems present in the premises and the necessary control measures.
The assessment should include identification and evaluation of potential sources of risk and the particular means by which exposure to legionella bacteria is to be prevented; or if prevention is not reasonably practicable, the particular means by which the risk from exposure to legionella bacteria is to be controlled. When the assessment demonstrates that there is no reasonably foreseeable risk or that risks are insignificant and unlikely to increase, no further assessment or measures are necessary. However, should the situation change, the assessment needs to be reviewed and any necessary changes implemented. The assessment needs to be reviewed regularly and, in any case, whenever there is reason to believe that the original assessment may no longer be valid.

Guidance

Before any formal health and safety management system for water systems can be implemented, a risk assessment has to be carried out to decide the possible risks. The purpose of the assessment is to enable a decision to decide:
* the risk to health, i.e. whether the potential for harm to health from exposure is reasonably foreseeable unless adequate precautionary measures are taken;
* the necessary measures to prevent, or adequately control, the risk from exposure or legionella bacteria.
The risk assessment also enables the person on whom the statutory duty falls to show that all the pertinent factors, and the steps needed to prevent or control the risk, have been considered.
In conducting the assessment, the person on whom the statutory duty falls needs to have access to competent help and advice. This source of advice may not necessarily be within the person's organisation but may be from a consultancy, water treatment company or a person experienced in carrying out risk assessments. Employers are required to consult employees or their representatives about the arrangements for getting components help and advice.
It is the duty of the responsible person to make reasonable enquiries to ensure that organisations such as water treatment companies or consultants, together with personnel from the occupier's organisation, are competent and suitably trained and have the necessary equipment to carry out their duties within the written scheme in a safe and adequate manner.

Carrying out a risk assessment

A number of factors are required to create a risk of acquiring legionellosis, such as;
* the presence of legionella bacteria;
* conditions suitable for multiplication of the organisms e.g. suitable temperature (20C-45C) and a source of nutrients e.g. sludge, scale, rust, algae and other organic matter;
* a means of creating and disseminating breathable droplets e.g. the aerosol generated by a cooling tower or shower; and the presence (and numbers) of people who may be exposed, especially in premises where occupants are particularly vulnerable, e.g. healthcare.
While there will inevitably be common factors associated with the many and varied types of premises being assessed, the individual nature of each site should be taken into account. In complex systems or premises, a site survey of all the water systems should be carried out and should include an asset register of all associated plant, pumps, strainers and other relevant items. This should include an up-to-date
drawing/diagram showing the layout of the plant or system, including parts temporarily out of use. A schematic diagram would be sufficient. It should then be decided which parts of the water system (for example, which specific equipment and services) may pose a risk to those at work or other people.
The following list contains some of the factors which should be considered, as appropriate, when carrying out the assessment: the source of system supply water (for example, whether from a mains supply or not) possible sources of contamination of the supply water within the premises before it reaches the cold water storage cistern, calorifier, cooling tower or any other system using water that may present a risk of exposure to legionella bacteria; the normal plant operating characteristics; and unusual, but reasonably foreseeable operating conditions (for example, breakdowns).

When there is a risk, the significant findings of the assessment should be recorded (if there are five or more employees). In any case, it may be necessary to record sufficient details of the assessment to be able to show that it has been done. The record of the assessment should be linked to other relevant health and safety records and, in particular, to the written scheme.
Employers are required to consult employees or their representatives on the identified risks of exposure to legionella bacteria and on the measures and actions taken to control the risks. The employees should be given an opportunity to comment on the assessment and control measures and the employer has to take account of these views. It is, therefore, important for employers to publicise to employees that a legionella risk assessment has been performed, and one means by which employers could ensure that employees are informed of the measures and actions taken to control risks, and have an opportunity to comment on the risk assessment, would be by displaying the appropriate parts of the risk assessment. It is essential that the effectiveness of the control measures is monitored and decisions made on the frequency and manner of this monitoring.

The assessment should be reviewed regularly (at least every two years) and, whenever there is reason to suspect that it is no longer valid. An indication of when to review the assessment and what needs to be reviewed should be recorded. This may result from, for example:
* changes to the water system or its use;
* changes to the use of the building in which the water system is installed;
* the availability of new information about risks or control measures;
* the results of checks indicating that control measures are no longer effective;
* a case of Legionnaires' Disease/legionellosis is associated with the system.

< Back - Next >