Information update provided by Refcom August 2020
Information Provided by REFCOM
1 CORONAVIRUS COVID-19
The current coronavirus (COVID-19) outbreak is a fluid one with Government and medical professional advice changing rapidly. This statement is based on the best advice currently available at the time of writing. Government and NHS websites should be consulted for any rapidly developing changes to the situation. This guidance is purely about the likelihood of how an air conditioning system can or would spread a virus such as COVID-19, and what building owners can do to prevent the spread through common ventilation systems.
2 BACKGROUND
Recent newspaper stories have been widely circulated suggesting that research has suggested that “the coronavirus could be spread by air conditioning systems”. As with many stories like this in the media, a degree of caution should be taken with regard to the veracity or accuracy of the statements made. Air conditioning is often an easy scapegoat target when there is an outbreak of any kind – think of any Legionella outbreak and how the media immediately blames air conditioning despite the fact that we very rarely use the type of air conditioning in the UK where legionella bacteria can proliferate.
The recent reports of research from Singapore seem to suggest from finding “traces of the virus” in “an air duct connected to the room of a patient” who had tested positive for the virus, that the natural conclusion was that the virus was being transferred via the air flowing through the duct. Not only is this unscientific because it does not consider the distinct probability that someone has touched the outlet grille and left the trace amount there, but the scaremongering this creates is unhelpful to those trying to get to grips with the reality of the situation.
3 PREVENTION
Having said that, any airborne contaminants can be minimised, if not eliminated, by proper and effective filtration and regular cleaning and maintenance of ventilation systems. A clean ventilation system is an essential part of a healthy building and it is essential that any ventilation system serving a building where confirmed cases have been diagnosed are sanitised in accordance with best practice, and that any buildings where no cases have been confirmed have their ventilation system cleaned to industry best practice as a preventative measure during this time and on-going.
The National Association of Air Duct Specialists UK (NAADUK) has reviewed and updated its guidance document for its members and all building managers.
The 2ndReview gives further clarification and understanding of the importance of ventilation and ventilation systems to help fight against the coronavirus.
It is now acknowledged worldwide and by Government that a clean ventilation system assists in keeping the indoor air quality free from airborne infections. Equally, waste systems within buildings also have an impact on the airborne infection and further guidance is documented in the guidance.
On 25 August 2020, the World Health Organisation (WHO) document – COVID-19 Management in hotels and other entities of the accommodation sector interim guidance states: –
‘Ventilation and air conditioning. Ventilation is an important factor in preventing spread of the virus that causes COVID-19.
One of the 12 points raised by the WHO document is: ‘If HVAC systems are used, they should be regularly inspected, maintained, and cleaned.
Rigorous standards for installation and maintenance of ventilation systems are essential to ensure that they are effective and safe.
Attention should be given, as in normal circumstances, to monitoring the condition of filters and, if possible, increasing the central air filtration as high as possible without significantly diminishing design airflow.’
It also recommends that consultation with a heating, ventilation, and air conditioning (HVAC) professional should be carried out.
This guidance is supplementary to all government guidelines in relation to social distancing, hand washing, essential travel and staying at home, etc.
The scope is limited to commercial and public buildings such as offices, factories, schools and hotels where normal social transmission is possible. Hospitals and healthcare facilities are excluded due to the higher risk of contact with COVID-19 and the specialised work procedures required.
It is crucial that the spread of the coronavirus can be reduced by maximising a clean ventilation system. However, anecdotal evidence proves that many systems are not clean to relevant standards.
‘We encourage all our members to promote to their clients the importance of cleaning and maintaining the ventilation systems on a regular basis.”
The 2ndReview guidance note is available freely on the NAADUK website at www.naaduk.co.uk
Common Questions of COVID-19
Can COVID-19 be transmitted through air conditioning systems?
At this stage, there is no evidence that COVID-19 can be spread through air conditioning systems. Please note, however, that organisations around the world are assessing ongoing research on the ways COVID-19 is spread and will continue to share updated findings.
According to WHO, studies to date suggest that the virus that causes COVID-19 is mainly transmitted through contact with respiratory droplets rather than through the air.
When someone with COVID-19 coughs, sneezes, talks or even exhales, these droplets land on nearby objects and surfaces. Other people can become infected with the virus by touching these objects or surfaces, then touching their eyes, nose or mouth.
People can also become infected with the virus if they directly inhale airborne droplets from a person with COVID-19 who has expelled the droplets from their mouth.
The WHO recommends staying more than one metre away from a person who is sick. Research shows that airborne droplets can travel much further than one metre so it’s important to be mindful of this when you are near other people. How far airborne droplets carrying the virus can travel depends on air movement but can be several meters.
The WHO has also provided specific advice on the use of fans. It notes that table or pedestal fans are safe for air circulation among family members living together who are not infected with the virus. However, fans should be avoided when people who are not part of the immediate family are visiting, since some people could have the virus despite not having symptoms. Air blowing from an infected person directly at another in closed spaces may increase the transmission of the virus from one person to another.
What actions are required for workplace heating, ventilation and air conditioning (HVAC) systems?
Well-designed and maintained HVAC systems can help control the spread of COVID-19.
The WHO recommends increasing outdoor air ventilation using initiatives such as economy cycles, and avoiding recirculation of air. Building owners and operators should seek qualified advice on increasing ventilation in existing systems.
In line with guidance from SafeWork Australia, AIRAH recommends that employers seek confirmation from their building owner or facilities manager that the air conditioning system is properly designed and maintained.
Also, keeping relative humidity between 40 and 60 per cent will create conditions that reduce the risk of infection through inhalation of airborne droplets carrying the virus. Research from the International Society of Indoor Air Quality and Climate (ISIAQ) shows that viruses survive better at increased humidity with 60 per cent active above 60 per cent relative humidity.
Low humidity in occupied buildings should be avoided as this can dry out the mucous membrane which is one of our primary means of defence. ISIAQ research shows that virus survival decreases with decreasing humidity.
The WHO recommends increasing air filtration to as high as possible without significantly diminishing design airflow. AIRAH strongly advises seeking qualified advice that effective air filters at the recommended performance level have been selected and maintained appropriately.
The following interview with ASHRAE presidential member William Bahnfleth contains useful information about the effectiveness of filters, UV and other HVAC technologies in controlling COVID-19.
Please note that some ventilation systems, such as those in carparks, do not recirculate – all air is exhausted directly to the atmosphere. These systems are therefore highly unlikely to spread the virus unless they feed into nearby air intakes for other HVAC systems.