Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

1. Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation Presented by FaatiemaSalief CSIR Built Environment Monday 25 July 2011

2. Airborne transmission of TB TB IPC – focus on environmental control measures What is ventilation? And how can it be used in TB IPC? Important concepts in ventilation design “Open this window – Fresh air fights TB” Case studies Measurements and instrumentation Things to take with you from this presentation Overview of the presentation: Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

3. The airborne transmission of TB • Large droplets fall to the floor • Smaller drops become aerosolised • Droplet nuclei of about 5 microns are formed • Environmental conditions must be conducive to pathogen survival (Temperature, humidity) Illustration of particle dispersal when a person sneezes Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

4. Administrative Environmental Personal TB Infection Prevention and Control What measures can be taken to minimise the opportunity for infectious particles to be liberated into the air? What measures can be taken to remove infectious particles from the air? What measures can be taken to protect ourselves against infection? Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

5. Ventilation as a solution for TB IPC • C is the expected number of new cases • S is the number of exposed susceptible individuals • I is the number of sources of infectious aerosols • q is the generation rate of infectious agents • p is the breathing rate of exposed individuals • t is the exposure time • Q is the ventilation rate Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

6. Concepts of ventilation – The dilution principle Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

7. Concepts of ventilation – The dilution principle exhaust inlet The first air change removes 63% of potentially infectious droplets Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

8. Concepts of ventilation – The dilution principle exhaust inlet The second air change removes 84% of potentially infectious droplets Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

9. Concepts of ventilation – The dilution principle • The WHO and CDC recommends 12 ACH for TB IPC in high risk settings • Why 12 ACH? • It will take approximately 24 minutes to remove 99.9% of infectious droplets at 12 ACH Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

10. Concepts of ventilation – The airflow pattern • Airflow should be from clean areas to “dirty” areas • Contaminated air should be exhausted directly to the outside. Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

11. Can we successfully achieve these ventilation standards? • Mechanical ventilation - ventilation rate, pressure cascading, thermal comfort, etc. • Airborne Infection Isolation Rooms (AIIRs) • Filtration, exhaust design • Maintenance • Cost of an effective system? Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

12. Can we successfully achieve these ventilation standards in our resource constrained settings? • Natural ventilation Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

13. Can we successfully achieve these ventilation standards in our resource constrained settings? • Wind pressure and buoyancy forces • Single-sided and cross-ventilation • Stack effect Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

14. Can we successfully achieve these ventilation standards in our resource constrained settings? • Natural ventilation – ventilation rates? pressure cascading? thermal comfort? • Maintenance? • Costs? Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

15. Lets apply these principles by looking at some case studies Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

16. Investigating solutions for home-based care (CSIR 2011) Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

17. Investigating solutions for home-based care, CSIR 2011 • Typical subsidy house • Where is patient most likely to be? • Ventilation rates? • Airflow patterns? Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

18. Investigating solutions for home-based care, CSIR 2011 Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

19. Investigating solutions for home-based care, CSIR 2011 Bedroom 2 window open All windows closed Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

20. Investigating solutions for home-based care, CSIR 2011 Single-sided ventilation with cross-ventilation Cross-ventilation Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

21. Investigating solutions for home-based care, CSIR 2011 • All windows closed – 0.6 ACH • Bedroom 2 window opened – 8 ACH • Cross-ventilation – 17 ACH • Single-sided ventilation with cross-ventilation – 7 ACH Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

22. Measurements and Instruments • Predominant wind conditions • Windward and leeward side • Measure on the windward side velocity • Measure the openable area • Calculate the flow rate, Q = A x v • We can relate the flow rate to ACH via the volume of the room • Time-dependant calculations Ventilation for Health Care Facilities: Principles, challenges, measurements and optimisation

23. References http://www.thinking-outside-of-the-square.com/blog/wp-content/2009/02/sneeze-k-171.jpg http://www.topbulb.com/find/uv.asp http://www.technilamp.co.za/Products/bUltraVioletb/GermicidalIrradiation/tabid/6412/Default.aspx http://www.sciencephoto.com/images/download_lo_res.html?id=662201106 W Kowalski. Ultraviolet germicidal irradiation handbook. – UVGI for air and surface disinfection. Springer. 2009. http://www.uvcomparison.com/uvscience.php Department of Health and Human Services., Centers for Disease Control and Prevention., National Institute for Occupational Safety and Health., 2009. Environmental Control for Tuberculosis: Basic Upper-Room Ultraviolet Germicidal Irradiation Guidelines for Healthcare Settings. Escombe, R.A., Moore, D.J.A., Gilman, R.H., Navincopa, M., Ticona, E., Mitchell, B., Noakes, C,. Martı´nez, C., Sheen,P., Ramirez, R., Quino, W., Gonzalez, A., Friedland, J.S., Evans, C.A., 2009. Natural Ventilation for the Prevention of Airborne Contagion. PLoS Medicine 6:3, 0-11. www.plosmedicine.org . Escombe, R.A., Oese, C.C., Gilman, R.H., Navincopa, M., Pan, W., Martı´nez, C., Chacaltana, J., Rodrı´guez, R., Moore, D.J.A., Friedland, J.S., Evans, C.A., 2007. Upper-Room Ultraviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission PLoS Medicine 4:2, 309-317. www.plosmedicine.org . Nardell, E.A., 2010. Progress in the Application of Ultraviolet Germicidal Irradiation. American Society for Photobiology. Powerpoint accessed www.ghdonline . Xu, P., Peccia, J., Fabian, P., Martyny, J.W., Fennelly, K.P., Hernandez, M., Miller S.L., 2003. Efficacy of ultraviolet germicidal irradiation of upper-room air in inactivating airborne bacterial spores and mycobacteria in full-scale studies. Atmospheric Environment 37, 405–419.

24. CSIR Built Environment • Architectural Engineering Research Group • Dirk Conradie • FaatiemaSalie • Geoff Abbott • Jeremy Gibberd • LoratoMotsatsi • NkhensaniBaloyi • Peta de Jager • Sheldon Bole • ThabangMolefi • TichoanaKumurai • Sidney Parsons