Professor J.A. Swaffield FRSE. Emeritus Professor Heriot Watt University, Edinburgh.

1. World Plumbing Day, Holyrood, March 11th 2010 Public health challenges for the 21st century. Professor J.A. Swaffield FRSE. Emeritus Professor Heriot Watt University, Edinburgh.

2. Public health challenges for the 21st century. The provision of safe and reliable sanitation faces a range of challenges in the 21st century. These include - Climate change driven water shortages and excesses will stress both water supply and drainage provision Migration to the mega cities of the developing world will stress existing infrastructure. Demographic changes in developed country housing needs will increase water supply demand while climate change dictates water conservation. Lack of planning controls and increased population density in developing cities will endanger public health as installed systems will become stressed and inadequate to meet the applied demand. The sale of design codes internationally without reference to cultural and regional requirements will confuse designers and lead to poor design.

3. Public health challenges for the 21st century. Meeting these challenges will require coordinated action by organisations working in partnership. This has been the objective of the World Plumbing Council Partnerships must be formed that involve the construction industry, manufacturers, building owners and operators, government and planning authorities, design code organisations, public health and building services engineering consultants, medical and public health professionals and research organisations

4. Public health challenges for the 21st century. Two examples of partnerships formed to address public health issues arising from poor drainage system design exacerbated by increased population density and infection cross contamination due to system operation and poor or non-existant maintenance will be presented – both unfortunately taken from Hong Kong but representative of international concerns.

5. Public health challenges for the 21st century. The Pak Tin housing complex in Hong Kong is an example of potential public health risks as a result of increased population density, undersized drainage and poor design. Show video here Show video here

6. Public health challenges for the 21st century. This video demonstrates the effect of stack base surcharge in generating positive transient pressures sufficient to destroy an appliance trap seal – in this case a w.c. – leading to the ejection of foul water and waste into the bathrooms on the lower 10 floors of this 50 storey housing complex.

7. Solution to public health issues as a result of stack base surcharge in a Hong Kong housing block – Active Control Variable volume containment device or Positive Air Pressure Attenuator, PAPA Diverted flow maintains and gradually reduces entrained airflow, minimising transient. Positive air pressure transients in stack eject trap seal water – a health hazard.

8. Public health challenges for the 21st century. The PAPA device developed at Heriot Watt University in conjunction with a major manufacturer, Studor Ltd, has been used in Hong Kong to combat the extreme effects of stack base surcharge caused by under design of the drainage system OR lack of knowledge of likely building population The following video demonstrate its action. SHOW Video Here

9. Laboratory stack base surcharge simulation

10. AAV PAPA Trap Surcharge at stack base. Video view Stack base surge may blow trap seals Test rig includes a trap 20 m above the stack base. Closure of the airpath generates a +ve transient that displaces trap seal water.

11. AAV PAPA Trap Surcharge at stack base. Video view Multiple PAPA installation enhances control Two PAPA installed 10m and 40m above stack base, trap 20 m higher. Note PAPA deflates as initial water downflow established in stack. Maximum inflation reduced due to second unit.

12. Public health challenges for the 21st century. Solution – multiple P.A.P.A.TM installation

13. Airborne spread of SARS in Amoy Gardens Hong Kong 2003 • World Health Organisation Press Release WHO/70: • “droplets originating from virus-rich excreta… re-entered into residents apartments via sewage and drainage systems where there were strong upwards air flows, inadequate ‘traps’ and non-functional water seals.” • Virus transmitted via open floor drain traps • 321 infected cases • 42 deaths SARS Coronavirus

14. Floor Drain WHB Shower WC Floor Drain Shower WHB WC Dry TRAP WHB Shower WC Stack pipe Vent pipe SARS event, Amoy Gardens, Hong Kong, 2003 Route of SARS cross-contamination - 321 infected residents - 42 fatalities

15. Simulating the inter-apartment route of the SARS cross contamination Route identified by public health teams in Hong Kong. Simulations using the HWU AIRNET model Floor Drain Potential route of contamination to adjacent apartment blocks WHB Shower WC Apartment infected with SARS Floor Drain Shower WHB WC Apartment infected with SARS Post event analysis of the air flow paths confirmed the combination of bathroom fan and dry floor drain as the primary cross contamination route. Floor Drain WHB Shower WC Vertical Stack Vent stack

16. Public health challenges for the 21st century. The 2003 SARS event in Amoy Gardens was a major wake up call for the building services and public health industry. In 2005 a partnership was set to address the detection of depleted trap seals – an industry wide coalition that embodied the objectives of the World Plumbing Council – including Buro Happold CIBSE SoPHE RBS WPC Dept of Health IAPMO (US) Studor SNIPEF HWU The consortium was led by Heriot Watt University and funded by EPSRC and contributions from IAPMO, SNIPEF and Studor. The outcome is a non-invasive remote defective trap seal detection device already site trialed in a Dundee housing block, Heriot Watt, an RBS building in Glasgow and the Royal Infirmary in Edinburgh. The device will be launched onto the market in 2010.

17. Defective trap seal identification – a research led response to the SARS analysis. Low amplitude air pressure transient propagation in drainage and vent systems obeys ALL the laws of surge propagation. Therefore the reflection of a transient by an open or a water filled trap will vary from -1 to +1. This change in system response to an applied transient may be used to identify the location of the open trap as the propagation speed is known. A

18. Public health challenges for the 21st century. This presentation has been based on the work of the Drainage Research Group at Heriot Watt University and its partners – working together to further the public health agenda required to meet the challenges of the 21st century. Thank you for listening.