The engineering involved in creating a safe and pleasant air atmosphere is actually a very delicate balancing act. Hospitals and day surgeries, even GPs have to cater to patient and staff comfort while creating an environment hostile to whatever manages to walk in through the filter-less front door, and into the workspace.

HVAC systems, even those with HEPA filters, are seen as a potential threat to positive indoor air quality (IAQ) success, as the ducts themselves can become ideal sites for colonisation of moulds and fungi, which can then be aspirated effectively throughout the system. 

Making a home for the pathogens to thrive

Legionnaire's Disease is perhaps the most widely known illness that is spread in several ways but most spectacularly through contaminated cooling tower water being disseminated through commercial buildings via the HVAC system.

In the outside world, most people’s immunosuppressant systems can brush off a light dusting of germs. However, many of the people in the healthcare facilities are patients, with compromised immune systems ripe for infection.

Airepure Australia has published several papers on this subject. The company has a range of filtration systems, including those for operating theatres and laboratories, and was a supplier to the Victorian Comprehensive Cancer Centre. Airpure says that HEPA filters can be augmented by additional hardware, such as UV light that can be utilised within the ducted system. UV light is known as an effective germicidal system that can lighten the pathogen load within large systems.

But of course, the architecture plays a vital role. A building or practice with less than ideal humidity or damp control will set itself up for ongoing microbial issues.

Effective but harsh cleaning practices such as chemical washing may satisfy surface cleaning but can exude offensive and troublesome gases and fumes that will exacerbate patient discomfort. 

For this purpose, Rockcote has a range of paints designed for healthcare – designed to not only be robust as far as scrapes and abrasion is concerned, but also to be able to withstand ‘project cleaning’ of rooms.

Their acrylic paint is less porous than other paints, which makes it less prone to surface growths. And when there is damage that needs urgent repair, the low VOC paint has low odour and quick drying properties that allows rooms to be turned around quickly.

Providing new air

The evacuation of ‘old’ air, or exchanging of air, is a constant event in healthcare.  The rate and ratio are dependent on the situation i.e. operating theatres have 20 complete exchanges of air each hour, an isolation room (where patients with highly infectious diseases such as measles may be situated) has different rates and also faces more frequent attendance of staff that breach the formal containment lines.

Negative air pressure rooms have a constant intake and exhaust of air, with the filtered exhaust/air flowing away from the hospital’s general population space.

Room pressurisation, while once only seen in very few rooms in major hospitals, is now far more widespread and effectively and invisibly handles the task. However, with greater use comes greater expense through both purchasing, installation, monitoring and rigorous maintenance and repair.

And this is perhaps where the difference in hospital design over the last fifty years is most striking, with the almost entirely lost concept of ‘wards’ or shared rooms. The ‘Nightingale wards’, as they were called, were designed as a long narrow room with beds along each long side, and shared toilet facilities at one end.

We then progressed to rooms that held fewer patients, but six beds were not uncommon, then down to four, two and yes, single rooms are the expected standard now, even in public hospitals, and each room is expected to have its own ensuite.

There is more to this move toward ‘private’ accommodation than resembles hotel or resort design. The advantages of this are a much-reduced transfer of pathogens as patients no longer pass each other on the way to the toilet, and staff that also no longer pass every patient in order to attend just the one. 

Of course, while rooms now have fewer people, they have more equipment, and the need for well-designed vent placement then becomes even more critical.


The full article can be found in the September-October edition of Infolink | BPN