Case Study: Successful Decontamination of an HVAC System s Ductwork Using Chlorine Dioxide Gas

Transcription

1 Canadian Biosafety Symposium Date: June 1, 2009 Place: Delta Halifax, Halifax Nova Scotia Case Study: Successful Decontamination of an HVAC System s Ductwork Using Chlorine Dioxide Gas Mark A. Czarneski Director of Technology 1

2 Overview 1. Reasons, Requirements & Choices 2. Equipment / Facility Setup 3. Pictures of Setup 4. Readings 5. Concerns & Conclusions 2

3 New Developments in Chlorine Dioxide Chlorine Dioxide Gas has been approved by NSF International under Annex G of NSF/ANSI 49 for the decontamination of BSC s Only 2 methods are approved for BSC decontamination 1983 Formaldehyde was approved 2008 Chlorine dioxide gas was approved. NO other method approved for BSC decontamination 3

4 Reason for Decontamination Ductwork was undersized and had to be modified BSL-2 & 3 work in lab Ductwork and Biological Safety Cabinets possibly contaminated with HIV - Human Immunodeficiency Virus HCV - Hepatitis C Virus Costly and time consuming for contractors to demolish / work in proper PPE if NOT decontaminated 4

5 Requirements for Decontamination Sterilant must travel long distances From 3 rd floor BSL-2/3 lab space up to 5 th floor HEPA housing Over 200 ft (61m) of hose to re-circulate gas from 3 rd floor to 5 th floor Sterilant must not be affected by temperature difference Hoses traveling through un-conditioned space, Mezzanine and stairwell not temperature controlled (50-60deg F / deg C) Lab space 70 deg F (21 deg C) Fully decontaminate duct work and BSC s and demonstrate 6 log reduction of BI s Biological Indicator Placed in each Exhaust Point to test process ( Positive control = 16 Ttl) 5

6 Choices Requirements Chlorine Dioxide Formaldehyde Hydrogen Peroxide True Gas NO (reaches all surfaces) Travel Long Distances NO Temperature effect NO (Fallout / re-polymerize) (Condense) Demonstrate 6 log reduction Carcinogen NO NO Residue NO NO Odor Detection (Safety) NO OSHA 8 hr TWA (time weighted average) 0.1 ppm 0.75 ppm 1.0 ppm Typical Concentrations 360 ppm ,000 ppm 750 ppm 6

7 What is Chlorine Dioxide (CD)? Properties: Yellow-Green Gas 1 Water Soluble 2 Boiling Point 11 o C 3 Tri-atomic Molecule Molecular Weight Ability to be monitored in real time with a photometric device. Not subject to condensation or affected by temperature gradients. 2. Ability to penetrate water (not all sterilants can penetrate water, vapors can not) 3. Chlorine dioxide is a true gas at room temperatures; which means excellent distribution and penetration. 7

8 Chlorine Dioxide Time Line Aqueous Germicide (Water Treatment Longest User) Chlorine Dioxide Recognized as a Gaseous Chemosterilizing Agent CSI CD-Cartridge Registered with US-EPA Mar 2004 Time 1811 First Preparation of Chlorine Dioxide 1940 Bleaching Agent (Pulp & Paper Industry Largest User) 1988 First Registered with the US-EPA for use as a sterilant World wide consumption of chlorine dioxide 4.5 million lbs/day (2.04million kg/day). 743,000 lbs (337,000 kg) released to atmosphere in Example: Maine allows 3 lb s / hour (1.4kg / hour)of CD to be emitted 8

9 Decontamination Cycle Typical Concentration and exposure 60-75% RH (10 min for rooms, 30 min for small chambers) 1 mg/l for 2 hours = 720 ppm hours (rooms) 5 mg/l for 30min = 900 ppm-hrs (small chambers) 400 ppm-hrs successful at University of Pennsylvania Example Cycle (small chamber) Concentration (mg/l) Pre-Condition Condition Charge Exposure Aeration Relative Humidity (%) 1 5 9

10 Total Equipment on Site 1 Chlorine Dioxide Generators 1 Chlorine cylinder 1 EMS Chlorine Dioxide Gas Sensor Module 4 Steam Fast Humidity Generators 15 Recirculation Blowers 200 ft (61m) 2 (51mm) hose (BSL-2 area) 200 ft (61m) 1/1/2 (38mm) hose (BSL-3 area) 800 ft (244m) 1/1/4 hose (From Tee assemblies to BSC s) Extension Cords Duct Tape 2 ft (0.6m) Wide Tape 3/8 (10mm) gas inject tubing ¼ (6mm) gas sample tubing 10

11 Time Line (How Long is the whole Process?) Day 1 arrive in afternoon and setup Uncrate generator and sensor module Place Tee assemblies Run Hoses to 5 th floor HEPA Housing from 3 rd floor Lab Run Hoses from Tee assembly to BSC s and Ceiling drops Run Gas injection and sample tubing Seal 13 BSC s (MOST OF WORK) Day 2 arrive in morning Start Decon process 10am Finish Decon process 12:30pm Breakdown equipment and re-crate 11

12 CD Gas Generation Technology Cl 2(g) + 2NaClO 2(s) 2ClO 2(g) + 2NaCl (s) Performed in solid phase (no liquids) Gas generated on demand Self-Contained reagents Simple to replace consumables Small portable generators Photometric measurement of concentration Real Time Repeatable Accurate Validated 12

13 BSL-2 Area Equipment 11 BSC s 1 CD gas injection point 3 sensing points 3 steam inject points 3 (4pt Tee assemblies) 1 (3pt Y assembly) 13

14 BSL-3 Area Equipment 2 BSC s 1 CD gas injection point 1 sensing points 1 steam inject points 1 (4pt Tee assemblies) 14

15 BSL-2 Area Hose from 5 th floor HEPA Housing Air Flow Direction 15

16 BSL-3 Area Air Flow Direction Air Flow Direction Air Flow Direction Hose from 5 th floor HEPA Housing 16

17 Connections to BSC s Pressure Relief Gas Injection Re-Circulation Hose 17

18 Connections Blowers to BSC s and Exhaust Grill Gas Sample & Steam Inject Air Flow Direction 2 Pipe Tee Assembly Hose from 5 th floor HEPA Housing 18

19 Connections to BSC s Air Flow Direction 19

20 Concentration Readings (mg/l) 20

21 Concerns Was Gas getting to each BSC (gas only injected into one BSC) Biological Indicators will Test Leakage from BSC s 21

22 Conclusions Complete kill of all Biological Indicators No physical residue observed Had Leakage, Leakage contained in BSL-2/3 labs (need to seal BSC s better) No visible indication of material degradation on any electronics Low Chlorine Dioxide Concentrations Average concentration 500 ppm for BSL-2 area Average concentration 830 ppm for BSL-3 area 1021 Lowest PPM-Hrs 1701 Highest PPM-Hrs 22

23 For more information contact: Mark A. Czarneski PO Box 549 Lebanon, NJ Phone: Fax: Revision Date: April 27,