When experts realised Covid-19 was being spread via aerosols, care homes had to move quickly to find ways of minimising the risk. Air Quality News reporter, Laura O’Neill, investigates how the Covid-19 crisis has highlighted widespread weakness in the UK’s approach to ventilation in care homes.
Research published by the Department of Health and Social Care found that being in a well-ventilated room can reduce the risk of Covid-19 infection by more than 70%.
Covid-19 is spread through the air by aerosols that are exhaled from the nose and mouth of an infected person as they breathe, speak, or cough. Therefore, being indoors, with no fresh air, the aerosols can remain suspended in the air for hours or fall to the ground or a nearby surface where they can survive for hours or even days.
A report looking at aerosol-transmitted influenza found that enhancing indoor air quality could be as effective in reducing the transmission of viruses as vaccinating 50-60% of the population.
At the same time, a study led by researchers at the University of Cambridge found that social distancing measures alone do not provide adequate protection from the virus, further emphasising the vital importance of ventilation in order to slow the spread of Covid-19.
The case for mechanical ventilation
Graeme Fox, head of technical at the Building Engineering Services Association (BESA) said the fact that many buildings, including thousands of care homes, had to rely on natural ventilation, such as opening windows, exposed a widespread weakness in the UK’s approach to building ventilation.
He told Air Quality News: ‘Natural ventilation is completely temperature and wind direction-dependent and is still likely to leave unventilated, stagnant spots around the room.
‘The path taken by air is critical and will be different depending on the layout of the space and the occupancy levels. Opening windows gives you no control over the direction of the outside air and no opportunity to filter it to remove potentially harmful pollutants coming in from outside.
‘However, an engineered mechanical ventilation approach gives the user control over the air movement and the ability to adjust the speed and direction of airflow.’
Mr Fox highlighted that developing an indoor air quality solution is unique to the space in question and the make-up of indoor air is a complex cocktail of potentially harmful elements
However, care home managers could start by simply measuring concentrations of CO2 to see if they are getting effective air dilution.
Mr Fox continued: ‘The CO2 works like a ‘canary in a cage’ to demonstrate whether appropriate ventilation rates are being achieved and, therefore, other potentially harmful elements are also being reduced, such as airborne viruses.
BESA advises aiming for air change rates of 10 litres per second (l/s) per person and CO2 concentrations below 800 parts per million.
This approach is also favoured by Professor Cath Noakes from the University of Leeds. She is a ventilation specialist and one of only two engineer members of the Scientific Advisory Group for Emergencies (SAGE) that has been helping the government navigate the pandemic.
‘The spaces that worry me the most are those that are naturally ventilated as these are temperature and wind dependent.
‘I advise the government that engineering controls should sit above the measures that rely on human behaviour such as distancing and wearing face coverings in any ‘hierarchy of risk control’.
‘This is not just about flow rates as it depends on the size of the space. 10l/s per person is ideal, but if people are close together and for an extended period, we may need more flow rate.
‘You can also have quite a lot of people in a large space with lower ventilation rates.’
Mechanical ventilation in practice
BESA has said that many viruses also thrive in cool, dry, and dark conditions, therefore improving humidity control should be another priority for care home managers.
Graeme Fox said: ‘Improving indoor air quality is not just about preventing the transmission of disease, there are also considerable long-term comfort, wellbeing (including mental health) and productivity benefits to be had from improving the indoor environment.
‘The issue of disease transmission has merely highlighted problems that we have been living with for years and we can enjoy the wider benefits long after Covid-19 has been dealt with.
‘This will be particularly important for buildings that house the elderly and vulnerable.’
Care UK said that when experts announced Covid-19 was being spread via aerosols, care homes had to move quickly to find ways of minimising the risk with very little government guidance.
The care provider invested in fogging machines and was one of the first providers to invest in air purifiers, which were already being widely used in Europe in social care settings.
Care UK’s head of projects for its property department service, Steve Appleton said: ‘With everything possible in place for traditional cleaning and sanitation measures, we knew we wanted to go one step further and so we turned to two pieces of technology to find the answers.
‘After much research, we sourced fogging machines which fill a large, enclosed space, such as a lounge or dining room, with a fine dry fog that disinfects the whole area.
‘We also road-tested misting machines but found we preferred the dry clean of the foggers. We found that the foggers envelop everything, cleaning behind light fittings and pipes and getting into the smallest places to ensure thorough sanitation.
‘We also invested in air purifiers that gently blow negative ions out into the surrounding environment.
‘These ions ‘charge’ particles, such as dust, pollen and viruses, that float in the air. This causes them to be attracted to surfaces like floors and desks.
‘As they fall to these surfaces, there is less chance of people breathing them in and they can be easily killed by the thorough and regular cleaning of surfaces carried out by our dedicated cleaning and maintenance teams.
‘To maximise their effect, they were installed mainly in the reception areas of homes, where there is the greatest volume of people passing through and most deliveries from outside the home come in that way too.
‘They have proved invaluable as an additional line of defence, once regular cleaning and sanitisation processes have been carried out. The benefits in the care homes will be felt beyond the pandemic, protecting residents and colleagues from the flu and other viruses for years to come.’
A paradigm shift in ventilation
BESA is now calling for legislation to be brought in that would make measuring and monitoring indoor air quality mandatory.
It says the UK’s lack of air hygiene regulations is in stark contrast with the strict public health controls imposed on food, sanitation and drinking water and therefore they are calling for a ‘paradigm shift’ in ventilation similar to the changes brought about almost 200 years ago in water sanitation and sewerage control.
The association is also calling for a building certification scheme to be brought in that follow the best advice from around the world, including guidance from the World Health Organisation (WHO) on ventilating spaces.
It says ambitious indoor air quality levels should also be enshrined in domestic legislation including Part F of the Building Regulations, which is currently being revised, and the forthcoming Environment Bill.
Air Quality News asked the department of health and social care what kind of guidance they issued around maintaining good air quality and ventilation in care homes during the pandemic and if they planned to issue any as we come out of the pandemic.
A Department of Health and Social Care spokesperson said: ‘The safety of NHS and social care staff has always been our top priority and we continue to work tirelessly to deliver PPE to protect those on the frontline.
‘PPE recommendations in the updated Infection Prevention and Control guidance are agreed upon by an expert group of clinicians and scientists from across all four nations of the UK, based on the latest clinical evidence.
‘Emerging evidence and data are continually monitored and reviewed, and the guidance will be amended accordingly if needed.’
The Department for Environment, Food and Rural Affairs has also been contacted for comment but at the time of going to press they are yet to respond.
This article first appeared in the Air Quality News Magazine.