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Supporting health and social care providers in Devon

Air purification in care homes

Advice on investment in air purification in care homes and other environments at high risk from the spread of infectious diseases

Author: Damian Furniss
Date: 8 February 2022

The paper presents evidence for the benefits of air ventilation, filtration, and purification systems in settings at high risk of outbreaks of airborne infectious diseases such as COVID-19 and advice on their deployment.
It follows a period of exploration of this issue with local and national experts in these and other aspects of Infection Prevention and Control and engagement with relevant research. It builds on advice issued by the Department of Health and Social Care in January 2022.
It is intended to inform local decision-making regarding investment – or the incentivisation of investment – in such systems.

• Devon County Council should publish advice contained in this paper via the Devon Provider Engagement Network.
• Devon County Council should consider these findings in the light of investment opportunities, which might include:
– By directing ring-fenced ASC COVID-19 finding
– By bidding for Contain Outbreak Management Funding
– By promoting among providers to encourage their own investment

Financial implications: None at this stage

1. Purpose

1.1 To summarise evidence for, and advice, on the mitigation of SARS-CoV-2 infection in high-risk care settings using air ventilation, filtration, and/or purification technologies.

1.2 To discuss opportunities for investing in such technologies.

2. Recommendations

2.1 Communicate the appendix of this paper to Devon Provider Engagement Network for their information, following referral to the Outbreaks Review Forum on 10th February 2022 for final sign-off involving Public Health and CCG IPC colleagues.

2.2 Consider future investment and/or incentivisation opportunities, including:
• By directing ring-fenced ASC Covid-19 finding
• By bidding for Contain Outbreak Management Funding
• By promoting among providers to encourage their own investment

3. Background

3.1 A previous iteration of this paper was referred the question of whether investment in air filtration technologies in care settings in Devon would be of short- and longer-term value in the mitigation of SARS-CoV-2 infection in high-risk care settings to the Outbreaks Review Forum which includes experts in Infection Prevention and Control and in Public Health.

3.2 Colleagues on the Outbreak Review Forum suggested additional sources of guidance and research as well as facilitating contacts with local and national experts in the field. This paper has been updated to include their information and advice.

3.3 Since the previous iteration of the paper the Department of Health and Social Care have issued advice on this matter. This is the basis of the advice summarised in the appendix.

4. Key Messages

4.1 SARS-CoV-2 is an airborne pathogen. Airborne transmission of viruses can be mitigated in four ways:
• Masks: with FFP2 more effective than surgical more effective than cloth face coverings
• Ventilation: but this can compromise the temperature of living space
• Air filtration: using High Efficiency Particulate Air (HEPA) filtering machines
• Air purification: using ultra-violet technologies.

4.2 There is a growing research base in the use of air filtration and/or purification technologies in health and care and during the pandemic they have increasingly been deployed in education settings. However, improving air quality does not obviate the guidance concerning other Infection, Prevention and Control measures including use of Personal Protective Equipment including masks, appropriate distancing, and good hygiene.

4.3 CO2 monitoring is a good proxy for measuring air quality in that it assesses air circulation. It can demonstrate the effectiveness of ventilation but not of air filtration or purification. It can indicate which spaces might benefit from improved ventilation or air filtration/purification.

4.4 Improving ventilation is usually the easiest and most effective means of improving air quality and reducing exposure to airborne infectious diseases. This is often done most easily by opening doors and windows but in some environments or during winter this can be more problematic. Structural changes can also improve ventilation but if not incorporated into the original building design are best done following a professional assessment.

4.5 Where improving ventilation is not structurally possible, or insufficient to sufficiently improve air circulation and reduce exposure to airborne infectious diseases, professional assessment can also explore air filtration and/or purification options. Such assessments are usually undertaken when the space is occupied to its fullest extent.

4.6 To make a significant difference, especially in larger spaces, a professional assessment and installation is advised to ensure the right equipment is installed in the right place importance of its proper usage ongoing maintenance is understood.

4.7 When considering such installations factors such as noise level (especially in bedrooms) and keeping the equipment continuously plugged, uncovered, cleaned and maintained. Maintenance costs can be significant as HEPA filters and UV bulbs must be cleaned and/or replaced. Mobile units can present a trip hazard or infection risk.

4.8 Filtration and purification technologies have different pros and cons. Filters can remove particles in addition to infectious agents. HEPA filters tend to improve in effectiveness until point of failure whereas UV bulbs tend to degrade.

5. Investment opportunities

5.1 Initially the Infection Control Fund was frequently used by providers to fund capital investment programmes e.g. to develop visiting facilities outside of main care home buildings. However, increasingly, grant funding has been used to meet the additional revenue costs of meeting government IPC guidance and maintain adequate staffing.

5.2 If, as appears increasingly likely, the government issues a plan for ‘learning to live with Covid’, infection risks will remain in high-risk settings which are also prone to outbreaks of other airborne pathogens. In care homes this should mean creating environments that minimise the risk of outbreaks through preventive rather than reactive approaches wherever feasible.

5.3 On that basis, it is suggested we consider future investment and/or incentivisation opportunities, including:
• By directing ring-fenced ASC COVID-19 finding
• By bidding for Contain Outbreak Management Funding
• By promoting among providers to encourage their own investment.

Appendix: ‘Fresh air in care homes’ circulated by DHSC January 2021


Fresh air is an important measure to help reduce the transmission of COVID-19 in indoor settings. Being in a room with good ventilation can reduce the risk of covid transmission by up to 70% as fresh air disperses virus particles which may linger in the air.

When someone with COVID-19 breathes, speaks, coughs or sneezes, they release particles (droplets and aerosols) containing the virus that causes COVID-19. While larger droplets fall quickly to the ground, aerosols containing the virus can remain suspended in the air. If someone else breathes in virus particles that are suspended in the air, they can become infected with COVID-19. This is known as airborne transmission. The more people who use or occupy an area, the greater the risk of airborne transmission. The risk increases if an area is poorly ventilated but bringing fresh air into a room and removing older stale air that might contain virus particles reduces the chance of spreading COVID-19. Good ventilation will not be able to mitigate against all transmission routes of COVID-19 and does not diminish the importance of other infection prevention and control (IPC) measures that you employ in your settings, such as hygiene measures and PPE use which are particularly important in reducing infection at close proximity.

This explainer lays out four ways to identify and improve poor ventilation, including the use of CO2 monitors and air cleaners. Efforts to improve ventilation sit alongside other infection, prevention and control measures and are not a replacement for them.

Natural ventilation

Natural ventilation just means using windows, air vents and doors to bring in fresh air. Improving ventilation is an approach recommended by SAGE and UKHSA in reducing the risk of infection from airborne pathogens. You do not need to keep windows fully open for prolonged periods in colder weather. You will want to balance natural ventilation with thermal comfort and further information on this can be found here. When opening windows and doors, you should be mindful of wider safety policies or risk assessments, such as on fire safety and security.

Mechanical ventilation

Mechanical ventilation means using a mechanical ventilation system to suck in fresh air and circulate it through a space.

If you already have a mechanical ventilation system, it is important that it is set to maximise fresh air and minimise air recirculation – otherwise it will only be moving potentially infected air around.

CO2 monitors

Carbon dioxide (CO2) monitors do not improve fresh air but can help identify poor ventilation so that it can be improved and reduce the risk of spreading COVID-19. During the pandemic they have been increasingly used in school classrooms for that purpose, with improved air quality shown as reducing the prevalence of infection by half.

CO2 monitors provide an indication of ventilation status but are not detecting the levels of COVID-19. CO2 monitors should be used by taking a series of readings during busier times. CO2 levels consistently higher than 1500ppm in an occupied room indicate poor ventilation and you should take action. CO2 levels below 800ppm are recommended for areas with increased respiratory activity such as via singing or exercising. Higher readings do not mean that you need to ask people to leave the space or setting immediately, but multiple high readings are a sign that you should take action to bring fresh air into that space.

Many designs are portable so you can easily move them around your full estate. Not all spaces are suitable for CO2 monitoring. Monitors are best suited to spaces with a consistent number of people for at least an hour. In care homes this may mean communal areas, staff or meeting rooms, and other multiple occupancy rooms. They are of limited use in large open spaces with higher ceilings or areas with fewer people, though other IPC measures remain important in these spaces. It is also not advised that CO2 monitors are used in spaces where air cleaning units are being deployed. This is because air cleaning units remove contaminants (such as coronavirus) from the air but do not remove CO2. Further advice on the use of CO2 monitors can be found here.

Air cleaning devices

The best way of ventilating a space to reduce infection risk is via fresh air, either through natural or mechanical ventilation. However, where this can’t be done, air cleaning devices can be useful in reducing airborne transmission and there is a developing research base for this in health, care, and education settings. Air cleaning devices are not, however, a substitute for ventilation and should not be used as a reason to reduce or not remediate poor ventilation in the long term.

There are several technologies used in air cleaning devices. The Scientific Advisory Group for Emergencies (SAGE) have recommended two technologies for settings where the ventilation is poor, and it is not possible to improve it by other means:
• High-efficiency particulate absorbing (HEPA) filters, which work by taking in air with the help of a fan and passing it through a very fine filter. Most of the particles and aerosols are caught by the filter and the cleaned air is then returned to the room.
• Covered UV-based germicidal (UV) cleaners, which use ultraviolet light to kill viruses.

A site-specific risk assessment should be conducted ahead of their use by an independent expert who should be accredited by the Heating, Ventilation, Air Conditioning and Refrigeration Association with demonstrable expertise in this specialist field. SAGE considered that other air cleaning technologies had only limited evidence for tackling COVID-19 and proposals involving them should be treated with caution.

Air cleaning devices will be most effective in communal areas. When deploying an air cleaning device, you should consider:
• Whether it is going to be effective for your space (for example, the size of space that it will effectively clean the air in)
• If you are using a HEPA filter, how you will manage the replacement and disposal of used filters If it is useful to have a more portable device that can be moved between occupied areas
• The noise or other impacts it could have, including if its placement could present a safety hazard.

For comparison, HEPA filters are currently being used in schools, in classrooms where CO2 monitoring has indicated poor ventilation and other mitigations have not been sufficient. You can see the models they are using here. These models have been chosen partly because they are quiet.

There is further advice on the use of air cleaning devices here.

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