Aerators and aerosols!!!! what comes to your mind? Saunas, spas and maybe the refreshing mist machines we occasionally see at festivals on a hot summers’ day. It all looks harmless enough – even pleasant. But how well do you know the microbiological content of the fine aerosols you encounter, be it in a spa, sauna, mister machine shower etc.? So how might aerators contribute to disease risks in a health or aged care facility? Should you consider them when you start putting a Water Risk Management Plan in place?
Nature of Aerosols
Below are two glasses of equal size but with different contents. One has clear water and the other has muddy and murky water. However if you pour the contents of glasses into spray bottles and spray into the atmosphere you can not tell the difference just by looking at the mist. Furthermore aerosol is so fine that it is invisible. If you can see mist then aerosol is certainly present. Of course more mist means more aerosol production. The invisible aerosol floats in the air column. It can travel over to 2 metres from a running tap in a basin. Consequently it is aerosol that carries live Legionella and other bacteria deep into the lungs causing disease. We hope this article will make you aware of the dangers of aerosol generating outlets.
When you turn the tap on to wash your hands what do you notice? Is the water stream bubbly and white with fine water droplets being dispersed or a steady clear water stream? Now let us take you through the different types of aerators.
- Usually consists of a fine mesh that eventually clogs up. Eventually a slime substance will prevail within the aerator.
- Produces aerosols that disperse into the air posing a risk to susceptible individuals with compromised immune systems.
- Typically draws up to 50% of air in the mixing chamber which is a concern in Aged and Health Care Facilities as the surrounding air can be contaminated.
- Produces a smaller shower pattern style of water
- Also mixes water and air and contains a mesh..
- Produces aerosols and restricts water flow.
Non – Aerated Laminar Flow
- Does not mix air and water.
- Does not disperse aerosols into the atmosphere.
- Recommended for Health Care and Aged Care Facilities.
- Gives a clear non – splashing stream.
Guidelines like the new “enHealth Guideilines for Legionella Control” and the “UK HSE L8 Legionella control regulations” agree. As you can see aerators increase the risks by creating more aerosol but also by creating stagnation. The EnHealth Guidelines state “In all cases, low flow or stagnant water can provide conditions that contribute to the growth of Legionella”. So we have explained how they create aerosol. So how do they cause stagnation?
Aerators contain a fine mesh that helps to disperse and aerate the water. Unfortunately this mesh acts as a filter catching debris. The other effect is it slows down the water flow (sometimes intentionally) causing stagnation. The mesh component on aerators harbours biofilm over time. So aerators become Legionella bacteria amplifiers. Next due to their nature they disperse aerosols into the air where susceptible individuals may inhale or aspirate the bacteria. The examples below are all of aerators we have removed from taps in health care facilities.
A build-up of biofilm within aerators indicates that the entire system from the point of entry onwards maybe contaminated. As a result the biofilm may well establish in the water systems and may be difficult to control. So a Water Safety Risk Management Plan should include on site audit and replacement of aerators with Laminar Flows. Evidence shows that point of entry disinfection will help manage and curb Legionella associated risks. Additionally onsite staff maintenance personnel and management need to be proactive. It is important to routine monitor water temperatures and flush weekly. It is essential to record and document these procedures.
Below is a video of a basin in an aged care facility during flushing immediately after the removing the aerator. The aerator and debris is on the edge of the basin to the left. This clearly demonstrates the need to keep aerators clean (or remove them) and flush outlets.
“in higher-risk areas such as those where immunocompromised patients are present, removing aerosol generating items (e.g. showers, misting devices, tap aerators) to reduce the likelihood of infection”
“Although water and plumbing controls are important to avoid or reduce the growth of Legionella, exposure controls are also needed to ensure that the patients, staﬀ and visitors of health care and aged care facilities are not at risk from aerosols that potentially contain Legionella.”
“The general principle is to reduce the chance of contaminated aerosols being generated, dispersed and inhaled by those groups most susceptible to Legionella infection. Many exposure control measures are labour intensive and, as such, their use is often limited to areas of greatest risk in a facility.”
“Legionnaires’ disease typically results from inhalation of aerosols or aspiration of water containing Legionella by a susceptible person”
In preparing your Water Safety Risk Management Plan a site audit is the first step. Part of this process is identifying the tap fittings that are installed, their location and options for removal or replacement. Otherwise if they can’t easily be removed then routine cleaning of aerators should be a priority. Also look for ways to reduce biofilm, reduce stagnation and reduce aerosol. Finally you can achieve all three of these goals by removing aerators. This is a simple low cost action.
enHealth. Guidelines for Legionella control in the operation and maintenance of drinking water distribution systems in health and aged care facilities (2015). http://www.health.gov.au/internet/main/publishing.nsf/Content/A12B57E41EC9F326CA257BF0001F9E7D/$File/Guidelines-Legionella-control.pdf
UK HSE Legionnaires’ disease. The control of legionella bacteria in water systems. Approved Code of Practice and Regulations (2013). http://www.hse.gov.uk/pubns/books/l8.htm