Healthy humidity

Vapac, relative humidity, humidification
Humidification as a value-adding service — Dave Mortimer.

Humidifying buildings could help keep bugs at bay and reduce sickness costs says Dave Mortimer of Vapac — thereby adding value to building projects.

We are all familiar with the symptoms of a dry atmosphere — sore throats, uncomfortable contact lenses and static electricity. Incorporating humidification helps a building’s HVAC system function more effectively and improve the health of its occupants — so why aren’t more buildings investing in the technology?

For many buildings such as museums, art galleries, auditoria and clinical environments (including operating theatres and burns units) a carefully controlled environment that includes humidification is an absolute necessity.

But humidification for many commercial building systems is often overlooked or regarded as unnecessary.

Research conducted over many years, shows that bacteria and viruses spread more readily in dry atmospheres. Without appropriate controls, indoor environments can be detrimental to health and provide a breeding ground for bacteria and viruses.

For buildings such as museums, this is the Museum of Wales in Cardiff, humidification is an absolute necessity.

Droplets emitted from a sneeze or cough evaporate, enabling the micro-organisms to remain suspended in the atmosphere for longer, which helps them to spread and increase the chances of inhalation by a building's occupants. Whereas in a more humid environment droplets tend to fall and are then only spread by coming into contact with the surfaces on which they fall. This is one of the reasons why hospitals promote the use of anti-bacterial cleansers on reception counters and entrances to wards. The practice is also becoming more commonplace in other public buildings.

The prevalence of Sick Building Syndrome (SBS) is a well-documented and recognised problem. The SBS phenomenon covers a wide range of symptoms related to a building or workplace — which can include headaches, dizziness, skin irritation, fatigue and many other symptoms.

The causes of SBS have yet to be clearly and definitively identified, but humidity or lack of it could be an important factor.

In the United States the Occupational Health & Safety Administration (OHSA) suggests that environments could be healthier if 40% RH is maintained, as this could help reduce the transmission of airborne viruses such as influenza.

This suggestion was reinforced by research carried out by Columbia University’s Dr Jeffrey Shaman. He identified a link between humidity and influenza and concluded that humidity can ‘greatly reduce the viability of the flu virus and the transmission of influenza’. Jeffrey Shaman is an atmospheric scientist at Columbia University in New York and the lead author of a study that identified the link between influenza and absolute humidity in 2007.

Humidity has been a topic of discussion by the National Health Service (NHS) and the Health & Safety Executive (HSE). Both have also carried out research and provide details of their investigations, along with general advice on their web sites. In addition, many health regions and some clinical commission groups (former primary care trusts) in the UK have published their own guidelines (South West Hampshire Primary Care Trust — management of pandemic influenza) which draw attention to virus survival and that it is ‘enhanced in conditions of cold temperature and low relative humidity’.

Humidity can greatly reduce the viability of the flu virus and the transmission of influenza.

In a paper published on-line (‘BMC infectious diseases), Tyler Koep, a Mayo Clinic PhD researcher in the US, has been tracking the effects of humidity inside buildings to test theories that controlling indoor humidity levels will help control the spread of the flu virus in schools, churches and other areas where large numbers congregate. He also believes raising humidity levels could provide a solution to minimising flu outbreaks and the spread of the virus.

The Building Services Research & Information Association (BSRIA) and the Chartered Institution of Building Services Engineers (CIBSE) also support increasing humidity and recommend maintaining indoor humidity above 40% RH. But humidification systems are often turned off to reduce operating costs.

The Co-operative Pharmacy estimates that 7.6 million working days are lost each year in the UK, costing the country an estimated £1.35 billion as a result of flu-related sickness. Lack of humidity in buildings could be compromising the health of occupants and lead to an increase in the number of days and incurring businesses additional costs.

Indoor environments are very complex, but the HVAC industry is armed with a wealth of information on indoor air quality. There is mounting research that humidification has a key role to play as part of an HVAC system. So why aren’t more buildings humidified?

Building designers and engineers are constantly faced with the challenges of developing buildings that operate efficiently and meet legislative requirements. This often leads to humidity systems being overlooked as they try to balance the need for a comfortable and healthy environment, equipment and the demands for reduced energy consumption.

A supply of fresh air with carefully balanced levels of humidity is essential for our well-being, and in areas where large numbers of people congregate, this could have a significant impact.

By introducing moisture into buildings, lost working days could be reduced — in which case humidification adds value to building projects and should not be underestimated.

Dave Mortimer is national sales manager with Vapac.

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