Hospital health

Every year over 5000 people die in the UK from a disease they catch in hospital. Another 88 000 Americans suffer the same fate, according to figures released at January's American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) meeting in Chicago.

In other words, thousands of people are going into hospital with one ailment, but dying from something completely different. Close to 100 000 Britons in total are infected by a new disease while in hospital, costing the National Health Service untold millions of pounds in extra treatment.

The US broadcaster NBC claimed that cross-contamination had affected one in 20 Americans and was a "danger of staggering proportions". It also puts the much higher profile outbreaks of legionnaires' disease into perspective – only five people died in the much-publicised epidemic last year in Cumbria.

Poor hygiene standards, overcrowding and the vulnerability of people with low immunity levels play a big part in creating this escalating contamination scandal. But building services engineers have also been battling to come up with a ventilation strategy that combats the deadly threat of secondary infections.

"These are big numbers and you also have to consider the overall cost to the state in terms of lost productivity and so on," says Frank Mills of Environmental Design Consultants in Preston. "We have just about got away with it in the past by using antibiotics to treat the infections, but they are now starting to break down in the face of more aggressive strains.

"There are a lot of factors involved, but getting the ventilation strategy right can go a huge way towards reducing the risk of cross-contamination."

Mills is a former chair of the international working party organised by ASHRAE to develop a design guide that will help engineers address the particular problems encountered in healthcare facilities. Five years in the making with input from engineers worldwide, HVAC systems design manual for hospitals and clinics is said to supercede all national documents on the issue and is due for publication this June.

Unhappy history
The history of ventilation in hospitals and clinics is littered with unhappy episodes. This is partly because hvac systems were, for many years, not considered central to the delivery of healthcare, according to Rick Hermans, chair of one of ASHRAE's technical committees working on ventilation standards.

He quoted an American Hospital Association publication from the 1960s that highlighted the extent of the problem at a time when the role of ventilation in supporting the healthcare delivery process was poorly understood: "If a child develops whooping cough while in hospital, he should, if possible, be sent home, since secondary pneumonia, caused by various bacteria other than causative organisms of whooping cough is the chief cause of death or lasting debility. A child is more likely to acquire these secondary infections in the hospital than at home."

This "pretty much hit the nail on the head," says Hermans. "Infection control is most often associated with the techniques and general practice of healthcare delivery in clinical services," he explained at the Chicago meeting. "Today, ventilation is an important component of a successful infection control programme and should be considered part of healthcare delivery. Unfortunately, infection control is not normally a design parameter for the novice ventilation engineer, nor do many ventilation designers understand properly the reasons for ventilation requirements to accomplish infection control.

"Adding to this difficulty are the number of published rules and guidelines for ventilation rates, filtration efficiencies and pressure control that have been adopted by both building codes and departments of health as requirements for designers," added Hermans. "Ventilation designers often use the required values and assume that they are absolute, using them not only as minimums, but as maximums too."

Spores, bacteria and viruses can all be carried from areas of acute sickness treatment to other parts of a building if air change rates are not correctly set; air filtration poorly carried out and pressure differences not established between areas.

"The fundamental premise of our manual is that a well-designed, hvac system augments the other facets of the built environment to offer a healing environment," says Anand Seth, chair of the design manual's technical committee. "It seeks to minimise the airborne transmission of viruses, bacteria, fungal spores and other bioaerosols; and minimise the impact of the building on its environment.

"Healthcare facilities are environments of controlled hazards. Exposure to aerosolised pharmaceuticals, airborne contagions and strong cleaning chemicals are examples of these hazards."

The ASHRAE manual will be used as the basis for training courses aimed at hospital design engineers, facilities managers, contractors, owners and infection control specialists. Subjects covered include: consideration for existing facilities; heating and cooling system design; air handling and distribution systems, including filtration needs; controls and instrumentation; and operation and maintenance.

However, the key relationship is between the system engineer and the healthcare specialists, says Hermans: "The experienced healthcare ventilation designer knows that the quality of the ventilation – temperature, humidity, velocity and filtration – in any healthcare space is determined by the care given and the condition of the patients in the space.

"The experienced designer knows that the quality of the ventilation plays an important role in infection control of some diseases…the proper level of ventilation quality may vary between spaces, climates and projects. When establishing the minimum requirements or guidelines for ventilation quality, engineers and healthcare professionals must work together. This co-operation has been achieved in the past," he adds.

The smoking issue
ASHRAE has also stuck to its guns over another controversial health issue – smoking. The Society's indoor air quality standard continues to apply only to areas where smoking is prohibited, despite efforts to have it allow for the effects of smoke. However, a compromise in the shape of an addendum to the standard has been drawn up to guide designers who are required to provide ventilation for spaces where smoking does take place.

"Smoking is not illegal, so we have to be able to give guidance on the design issues related to it," ASHRAE president Don Colliver said at the Chicago meeting. "Our guidance will help engineers explain to building owners how odours can be addressed – we do not say anything about the health effects."

ANSI/ASHRAE Standard 62-2001: Ventilation for acceptable indoor air quality sets minimum ventilation rates and other requirements for commercial and institutional buildings. The design guidance in addendum 62o addresses the use of ventilation to control odours from tobacco smoke. This was approved at the Chicago meeting.

It gives designers a method to determine the additional ventilation over what would be provided in a similar non-smoking area for the purpose of odour control only.

"Typically, the increase in ventilation is about 10 to 40 cfm/person over the non-smoking rate in spaces without heavy smoking," says the standard's committee chair Andrew Persily. "The actual increase will depend on the smoking rate and occupancy density of the specific space."

The importance of properly calculated ventilation rates to mitigate impacts on health, either direct or indirect, is clearly not lost on the 58 000 members of ASHRAE worldwide. It is also clear that governments – the US one in particular – look to the Society for guidance on such matters, whether it accepts a direct involvement in health issues or not.

"There are no guarantees, even with a proper ventilation strategy in place," says Mills. "But it is important to explain where the risks are and how building services engineers can play their part in minimising those risks."