Frequently Asked Questions
Control of Legionella
What is Legionella?
Legionellosis is a collective term for diseases caused by legionella bacteria including the most serious Legionnaires’ disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. Legionnaires’ disease is a potentially fatal form of pneumonia and everyone is susceptible to infection. The risk increases with age but some people are at higher risk including:
- people over 45 years of age
- smokers and heavy drinkers
- people suffering from chronic respiratory or kidney disease
- diabetes, lung and heart disease
- anyone with an impaired immune system
The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. They may also be found in purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems and spa pools.
If conditions are favourable, the bacteria may grow increasing the risks of Legionnaires’ disease and it is therefore important to control the risks by introducing appropriate measures outlined in Legionnaires’ disease – The Control of Legionella bacteria in water systems.
Where does it come from?
Legionella bacteria are widespread in natural water systems, e.g. rivers and ponds. However, the conditions are rarely right for people to catch the disease from these sources. Outbreaks of the illness occur from exposure to legionella growing in purpose-built systems where water is maintained at a temperature high enough to encourage growth, e.g. cooling towers, evaporative condensers, hot and cold water systems and spa pools used in all sorts of premises (work and domestic).
How do people get it?
People contract Legionnaires’ disease by inhaling small droplets of water (aerosols), suspended in the air, containing the bacteria. Certain conditions increase the risk from legionella if:
- the water temperature in all or some parts of the system may be between 20-45 °C, which is suitable for growth
- it is possible for breathable water droplets to be created and dispersed e.g. aerosol created by a cooling tower, or water outlets
- water is stored and/or re-circulated
- there are deposits that can support bacterial growth providing a source of nutrients for the organism e.g. rust, sludge, scale, organic matter and biofilms
What is Pseudomonas aeruginosa?
Pseudomonas aeruginosa is the definition of a tough bacterial strain, able to survive in harsh environments. It is found widely in soil and stagnant water, and can infect humans and plants.It does not usually cause illness in healthy people, but is described as an “opportunistic” organism, causing serious infection when our normal defences are weakened. This means that it represents a genuine threat to the most vulnerable hospital patients, most commonly intensive care patients, those with depleted immune systems such as cancer patients, people with severe burns and premature babies in neonatal units.
What kind of illness does it cause?
The severity and type of the illness it causes depends on its route into the body. If it enters lung tissue, for example in a cystic fibrosis patient, it can cause a form of pneumonia. Infection of a skin wound or burn can lead to extensive tissue damage or even septic shock. If the bacterium infects the gastro-intestinal system of a vulnerable patient, then a condition called “necrotising enterocolitis” can follow, which again causes severe tissue damage. This is the form most associated with premature babies.
How much of a problem is it in our hospitals?
Pseudomonas aeruginosa is a relatively common type of infection encountered in UK hospitals, and its tough nature and the severity of the symptoms it causes mean it is a priority for infection control departments. There have been a number of outbreaks in hospitals in the UK, with the source sometimes traced back to contaminated water in sinks and drains. It has the ability to survive for up to several days on surfaces, further increasing the risk of it being passed on to patients.
Latest figures suggest that the number of Pseudomonas infections is fairly steady, with between 3,700 and 4,000 cases reported to the Health Protection Agency each year. Nine out of 10 of these were the Pseudomonas aeruginosa strain. Rates were highest in the London region, and the majority of cases were in the elderly and babies under one year old.
How is it spread?
The usual route is through contaminated hands or medical equipment such as catheters and feeding tubes.
Infection control measures such as regular handwashing and decontamination of equipment are the most effective tactics to prevent its spread.
How can it be treated?
Once established in a weakened patient, a Pseudomonas aeruginosa infection is potentially a severe problem which requires immediate treatment.
While mortality from the infection varies depending on where the infection is, how soon it is treated and the underlying weakness of the patient, some studies suggest a third of infected patients may die.
The bacterium appears to have an inbuilt resistance to antibiotics, as well as the ability to mutate into new, even more resistant forms.
However, there are still a number of antibiotic drugs which can tackle it, and latest statistics in the UK suggest that the number of strains with resistance to any of these individual standard drugs remains fewer than one in 10.
Sick Building Syndrome
What is Sick Building Syndrome?
Sick building syndrome (SBS) is a poorly understood phenomenon where people have a range of symptoms related to a certain building, most often a workplace, and there is no specific identifiable cause.
What are the symptoms of SBS?
The symptoms of SBS may include:
- headaches and dizziness
- nausea (feeling sick)
- aches and pains
- fatigue (extreme tiredness)
- poor concentration
- shortness of breath or chest tightness
- eye and throat irritation
- irritated, blocked or running nose
- skin irritation (skin rashes, dry itchy skin)
The symptoms of SBS can appear on their own or in combination with each other and they may vary from day to day. Different individuals in the same building may have different symptoms. They usually improve or disappear altogether after leaving the building.
Who is affected by SBS?
Anyone can be affected by SBS, but office workers in modern buildings without opening windows and with mechanical ventilation or air conditioning are most at risk. This risk increases if they are employed in routine work that involves using display screen equipment.
Women appear to be more likely to develop the symptoms of SBS than men. However, this may be due to more women being employed in offices rather than a higher susceptibility.
In what environments does it occur?
SBS seems to be associated with certain types of buildings. Most cases of SBS occur in open-plan offices, although people sometimes develop the symptoms while in other buildings that are occupied by lots of people, such as:
What are the risk factors?
Since the 1970s, researchers have tried to identify what causes SBS. As yet, no single cause has been identified. However, most experts believe that SBS may be the result of a combination of different factors.
Possible risk factors for SBS may include:
- poor ventilation
- low humidity
- high temperature or changes in temperature throughout the day
- airborne particles, such as dust, carpet fibers or fungal spores
- airborne chemical pollutants, such as those from cleaning materials or furniture, or ozone produced by photocopiers and printers
- physical factors, such as electrostatic charges
- poor standards of cleanliness in the working environment
- poor lighting that causes glare or flicker on visual display units (VDUs)
- improper use of display screen equipment
- psychological factors, such as stress or low staff morale
Advice for employees
If you think that your working environment is making you ill, talk to your colleagues to see whether they are having similar symptoms.
If SBS appears to be a workplace issue, raise it with your health and safety representative. Your employer has a duty of care to investigate the problem.
The environmental health services of your local authority or your local Health and Safety Executive (HSE) office may also be able to provide help and advice about how to deal with SBS.
You can visit the Directgov website to find your local authority. To find your local HSE office you can call their helpline number on 0845 345 0055.
Visit your GP if you have symptoms of SBS that you are particularly concerned about.
The HSE recommends that employers take the steps outlined below to investigate the possible causes of SBS.
- Carry out an employee survey to find out whether symptoms are occurring more often than expected. It may also help to identify any obvious causes that can easily be fixed, such as adjusting the office temperature.
- Check the general cleanliness of the building, including checking that the vacuum cleaners are working properly, that they are regularly emptied and their filters are clean.
- Check that cleaning materials are being used properly and stored correctly.
- Check the operation of the heating, ventilation and air-conditioning system. In particular, the system that supplies fresh air should be checked.
- Check the condition and cleanliness of air filters, humidifiers, de-humidifiers and cooling towers.
- Check heating, ventilation and air-conditioning system maintenance schedules. Ensure that they are being followed properly.
Once the steps listed above have been completed and any necessary actions have been taken, employers should carry out another employee survey at a later date to find out whether the symptoms of SBS persist.
If SBS symptoms are still present, a more detailed investigation will be required. This can be carried out by a building services engineer or another similarly qualified consultant.
Legionella Risk Assessments
Who can undertake the risk assessment for legionella?
As an employer or a person in control of premises, you must appoint person or persons responsible for helping you manage your health and safety duties, e.g. take responsibility for managing risks. A competent person is someone with the necessary skills, knowledge and experience to manage health and safety, including the control measures. You could appoint one, or a combination of:
- one or more workers
- someone from outside your business
If you decide to employ contractors to carry out your risk assessment or other work, it is still the responsibility of the competent person to ensure that the work is carried out to the required standards. Remember, before you employ a contractor, you should be satisfied that they can do the work you want to the standard that you require. There are a number of external schemes to help you with this, eg A Code of Conduct for service providers.
How do I carry out a Legionella risk assessment?
The purpose of carrying out a risk assessment is to identify and assess any risks in your water system. The responsible person should understand your water systems and any associated equipment, in order to conclude whether the system is likely to create a risk from exposure to legionella, and should be able to identify whether:
- water is stored or re-circulated as part of your system
- the water temperature in some or all parts of the system is between 20–45 °C
- there are sources of nutrients such as rust, sludge, scale and organic matters
- conditions are present to encourage bacteria to multiply
- it is possible for water droplets to be produced and, if so, whether they could be dispersed over a wide area, eg showers and aerosols from cooling towers
- it is likely that any of your employees, residents, visitors etc are more susceptible to infection due to age, illness, a weakened immune system etc and whether they could be exposed to any contaminated water droplets
Your risk assessment should include:
- management responsibilities, including the name of competent person and a description of your system;
- potential sources of risk;
- any controls in place to control risks;
- monitoring, inspection and maintenance procedures;
- records of the monitoring results, inspections and checks carried out;
- arrangements to review the risk assessment regularly
If you decide that the risks are insignificant, your assessment is complete. You may not need take any further action at this stage but you should review the assessment regularly in case anything changes in your system.
If I am not storing hot or cold water in my system, do I need to carry out a risk assessment?
Yes. There may be other factors within your system that increase the risks of legionellosis, eg deadlegs, showerheads and/or long runs of pipe work containing warm water. A risk assessment should also consider anyone who could be potentially exposed to any legionella bacteria in your system, and particularly groups that are at a higher risk of contracting legionellosis. However, once you have completed your risk assessment you may decide that the risks are insignificant. If you do, you need take no further action other than to review the assessment regularly in case anything changes in your system.