DEFENDING BUILDINGS AGAINST BIOTERRORISM

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DEFENDING BUILDINGS AGAINST BIOTERRORISM
Filtration Solutions

• Wladyslaw Jan Kowalski, PE, PhD
• The Pennsylvania State University
• Department of Architectural Engineering

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Filtration Systems for Immune BuildingsOutline

• A Brief History of CBW Warfare
• Chemical Biological Weapons (CBW)
• Epidemiology of CBW Agents
• CBW Delivery Systems
• Buildings Ventilation Systems
• CBW Attack Scenarios
• Air Disinfection Air Cleaning Systems
• Simulation Results
• CBW Detection Systems
• Remediation

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A BRIEF HISTORY OF CBW WARFARE
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A BRIEF HISTORY OF CBW WARFARE
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Chemical Weapon Agents
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Biological Weapon Agents
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Pathogenic Microbes
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Database of BW Pathogens
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BW Agent Pathology
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Chemical Weapon Agents
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Toxins

• Poisons produced by organisms
• Bioregulators control physiology
• Operate with different mechanisms
• Some can be grown in culture

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MSDS for CBW Agents
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MSDS for BW Agents
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Most Dangerous Toxins
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Lethal Dose vs. Infectious Dose
For chemicals Lethal Dose vs. Incapacitating Dose
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Lethal Dose Curves BW Agents
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Lethal Dose Curves CW Agents
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CBW Delivery Systems

• Outdoor Dispersion
• Explosives
• Crop Dusters
• Sprayers / Aerosolizers
• Indoor Dispersion
• Explosives
• Sprayers / Aerosolizers
• Passive Release / Spills

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Indoor Dispersion
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Indoor Dispersion Mechanisms
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Released BW Agents are Invisible
Some Chemical Agents are Visible
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Aerosolizer
Can be used to aerosolize liquids or powders
Can be driven by a compressor, compressed air
tank, building air, AHU suction pressure
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Aerosol Generators
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Low Tech Aerosol Generators
Spray Guns
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Low Tech High Volume Spray Guns
Might be used with Chemicals
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High Tech Aerosol Generators

• Might be used with Biological Agents

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Aerosolization in Duct
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Ventilation Systems

• Natural Ventilation
• Constant Volume
• VAV Systems
• 100 Outside Air
• Other Systems
• Rooftop Locations for most tall buildings

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Placement Points in a Building Ventilation System
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Types of Buildings Relative Risk
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Commercial Buildings
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Government Buildings
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Food Entertainment
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Health Care Facilities
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Lodging Hotels
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Educational Facilities
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Mercantile Facilities
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Auditoriums Stadiums
May be vulnerable to a general area release
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Multizoned Buildings
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Immune Building Technologies

• Air Cleaning
• Dilution Ventilation
• Filtration
• Ultraviolet Germicidal Irradiation (UVGI)
• Charcoal Adsorption
• Detection Biosensors
• Isolation
• Security Measures

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Primary Air Cleaning Technologies
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Ventilation Systems
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Dilution Ventilation

• Most Buildings Recirculate Air
• 15-15 Outside Air is drawn in
• Variable Air Volume Systems adjust amount of
  outside air
• 100 Outside Air Systems
• Purge continuously
• Common in Health Care

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Filtration

• Filters come in various efficiencies
• Dust filters are common but have little effect on
  micron-size particles
• Nominal Filters 25 - 95
• HEPA Filters 99.97

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Filtration of BW Agents MERV 7
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Filtration of BW Agents MERV 9
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Filtration of BW Agents MERV 11
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Filtration of BW Agents MERV 13
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Filtration of BW Agents MERV 14
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Filtration of BW Agents MERV 17
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Penetration of HEPA Filters byBW Agents
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Ultraviolet Germicidal Irradiation

• UVGI can be effective when properly designed
• Destroys Viruses
• Destroys Most Bacteria
• Can Destroy Spores at High Power

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UVGI Effect on Pathogens
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Combined Filtration UVGI
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Lumalier UV Design Project

• High power UVGI system
• 25 filters
• Destroys 84 of anthrax spores
• Destroys 99 of smallpox virus
• Destroys 99 of TB bacilli

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Sizing UVGI with Filtration

• Determine each microbes removal from filter
  performance curves (call this kill rate)
• Determine each microbes kill rate after UVGI
  exposure ( kill rate 1 - survival )

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Possible CBW Attack Scenarios

• Scenario A Gradual release in AHU
• Scenario B Gradual Release in General Area
• Scenario C Sudden Release in Outside Air Intakes
• Scenario D Sudden Release in General Area
• Scenario E Outside Air Release

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Scenario A Gradual Release in AHU

• Contaminates all areas evenly
• Maximizes casualties in office buildings
• Surreptitious release
• Requires aerosol device

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Scenario B Gradual Release in General Area

• Highly contaminates local area
• Lower levels of contamination in other areas
• Less severe then Scenario A
• Requires release device

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Scenario C Sudden Release in OA Intakes

• Contaminates all areas evenly
• Requires no release device
• Requires OA intake access
• Less Severe than Scenario A
• Severity highly dependent on the presence of
  filtration

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Scenario D Sudden Release in General Area

• Highly contaminates local area
• Less contamination in other areas
• Less severe than other scenarios
• May require sudden release device
• or May be spilled or dumped
• May alert occupants

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Scenario E Outside Air Release

• Inefficient, requires large quantities to achieve
  high inlet concentrations
• Will impact multiple buildings
• Less severe for individual building than other
  scenarios
• Requires dispersion equipment
• The Classic Military Scenario

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CW Agents Atriums Smoke Vents
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Atriums Reversed Smoke Vents
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Elevator Shafts Stairwells

• Stack effect may increase dispersion
• May increase concentrations in upper or lower
  areas
• OA temperature can influence flow direction

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Special Case Auditoriums

• Air mixing is primary determinant of contaminant
  spread
• Unpredictable by simple zone models

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Simulation-Based Filter Selection

• Not dependent on removal rates
• Removal rates are arbitrary
• Removal rate criteria results in over-design
• Design Objective Protect Occupants
• Practical Design Criteria is to Minimize
  Casualties
• Simulation can be used to estimate fatalities

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Simulation of Attack Scenarios

• Evaluate Design Basis Scenarios
• Worst cases Scenario A, B, C
• Evaluate Design Basis BW Agents
• Anthrax, Smallpox, Botulinum
• Establish Baseline Release Quantity
• 99 Predicted Fatalities
• Evaluate Filter UVGI systems
• Filters (MERV 7-17)
• UVGI (URV 7-17)

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UVGI Rating Value (URV)

• Analogous to MERV
• 20 increments
• Design velocity assumed
• Spans range or typical minimums maximums
• Based on Average UVGI Intensity
• Critical Design Parameter is Average Intensity
• Defines UVGI System in Engineering Terms
• Not a Function of Dose
• Dose does not define system size

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MERV / URV Systems
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Simulation Results Worst Case
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Simulation Results Scenario ASlow Release in
AHU
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Simulation Results Scenario BSlow Release on
Main Floor
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Simulation Results Scenario CSudden Release in
OA Intake
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Simulation Conclusions

• Predicted fatalities provide a basis for sizing
  air cleaning components
• Only one ideal size exists for air cleaning
  components
• Critical size is a function of the building
  characteristics ventilation system
• Critical size is independent of air cleaning
  capacity and BW agent

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Detection Biosensors

• Some Biodetection Systems Exist
• Only a few BW agents can be detected
• Requires minimum 10-30 minutes
• Systems are Expensive
• Chemical Detection Systems exist
• Most CW agents can be detected
• Requires Minimum 2-4 minutes
• Systems are Expensive

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Biodetection Alternatives

• Particle Detectors
• Can detect presence of particles in the air
  instantly
• Expensive
• Air Samplers
• Cultured Plates can be inspected or evaluated by
  a Lab
• Takes time
• Not too expensive

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Detect-to-Isolate Architecture

• Only chemical agents can be rapidly detected
• Duct must be long enough to allow for response
  time
• Can be expensive

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Air Sampling for Detection

• Sample continuously
• Send to Lab each Wednesday Friday
• If Cultures Positive then Treat Occupants

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Detect-to-Treat Architecture
For BW Agents only
Example Case Anthrax spores

• Anthrax release in building on day 1
• Air Sampler Results on Day 3-5

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Detection Times Disease Progression Curves
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Personnel Protection

• Protective gear
• Safe Zones
• Emergency Planning
• Training Education
• Immunization

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Physical Security Measures

• Protection of HVAC Equipment
• Lockdown Equipment Rooms
• Bar or lock duct access doors
• Raise outside air intake ducts
• Screen or bar outside air intakes
• Alarms
• Video cameras
• outside air intakes
• Equipment rooms
• Rooftop equipment
• Metal Detectors

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CBW Post-Attack Remediation

• Decontamination of buildings and Equipment
• Chlorine dioxide being used for anthrax
• Destroys some materials, metals, furniture
• Leaves a residue
• Ozone could be used
• Destroys rubber and some organic materials
• Scrubbing with bleach
• Long-term UV exposure
• Long-term sunlight and outside air exposure

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Conclusions

• Various technologies can protect buildings
• Ventilation, Filtration, UVGI, Carbon adsorbers
• Various delivery mechanisms and scenarios are
  possible
• BW Agent Delivery may be surreptitious
• UVGI Filtration should be combined
• Systems can be sized based on Anthrax spores,
  smallpox, botulinum
• Simulation may be the best approach for sizing
  components
• Only one critical size exists for any air
  cleaning system

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