world trade center evacuation study

World Trade Center Evacuation Study

Epidemiology 256:

Environmental and Occupational EpidemiologyThursday, May 24, 2012

Robyn R.M. Gershon, MHS, DrPHPrincipal Investigator

NCDPNational Center for Disaster

PreparednessColumbia University

CPHPCenter for Public Health

PreparednessColumbia University

Funded by ASPH/CDC

World Trade Center

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Case Study Presentation:The World Trade Center Evacuation

Study• Pre-event facts (Case study book chapter)• Significance• Human Behaviors in Fire Emergencies• Basic Organizational and Structural Facts• WTC Evacuation Study• Case Study Questions

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Significance

• High rises may experience fires and other disaster events

• Certain iconic high rises and public assembly spaces may be likely terrorist targets

• Lessons identified and learned from high rise disasters, including the WTC disaster in 2001 may improve preparedness and response to other high rise events

Human Behaviors in Emergencies

What is Known:• People will generally not go towards smoke• Seek out groups, group size is important• People move towards and stay with group even if it

is not the best option• The faster groups form – the faster they evacuate

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Human Behaviors in Emergencies

What is Known:• Individual and group panic dependent on several

key factors• Information serves as motivator• Leadership is especially important in public spaces

– both for shaping group behaviors and for guidance• Familiarity helps groups to form and minimizes

panic

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Basic Organizational and Structural Facts

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South

North

WTC Complex

Typical World Trade Center Office Floor

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• AFTER 1993 BOMBING Port Authority NYNJ Instituted a new EP Program:

• PLANNING

• ORIENTATION

• EDUCATION

• PUBLIC ADDRESS ANNOUNCEMENTS

• OCCUPANT FIRE SAFETY TEAMS

• TEAM TRAINING

• FIRE DRILLS

• CRITIQUE

Preparing for Emergencies

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WTC Worker Protection Programs in Place 9/11

• Codes met and exceeded NYC fire and other applicable building safety codes

• Port Authority Program

• Floor warden system• Annual fire drills• PA system

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Design Features of High Rises

• High rise buildings – robust and redundant• Not usually designed for rapid, full building

evacuation• Not designed to withstand impact of fuel-laden

large aircraft in use today• Rescue of occupants located in inaccessible

areas of high rises above the point of impact is not possible

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WTC, 2001North Tower Impact

(Tower 1)

• 8:46am • 767, 10K gallons • Impact at 94-98th floors• Collapsed 1 hour and 42

minutes after impact

South Tower Impact

(Tower 2)

• 9:02am • 767, 10K gallons• Impact at 79-84th floors• Collapsed 57 minutes

after impact

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WTC Disaster,

2001Impact

Zones of Planes

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WTC Fatalities, 2001

• 411 first responders• 147 jetliner crew and passengers• 1,462 in North Tower (1,355 above impact, 93%)• 630 in South Tower (619 above impact, >95%)• 18 bystanders (on the ground)• 24 location unknown in WTC 1 and WTC 2• Total deaths: 2,692• 11% of occupants died, most above point of

impact

WTC Fatalities, 2001

• Age Range– Planes: 2 ½ years – 86 years– Building: 18 years – 79 years

• Post 9/11– 479 illness/deaths of workers at Ground Zero

or Fresh Kills Landfill– 149 traumatic deaths– 33 suicides

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The WTC Evacuation Study* Objectives

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• To identify individual, organizational, and environmental/structural (building) factors that affected evacuation and health outcomes

• To inform policies and practices that support safe evacuation of high-rise structures

• To inform preparedness for other mass evacuations

*Funded by CDC/NIOSH

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WTC Evacuation Study: Overview

Participatory Action Teams

Identification of Risk

Reduction Strategies& Recommendations

Feedback to Participants &Stakeholders

Preparation of Reports

Qualitative Processes &

Analyses

Formative Steps

Questionnaire Development

& Administration

Data Analysis

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WTC Evacuation Study Model

Knowledge(Experience)

BeliefsAttitudes,

Perceptions of Safety Climate,

Perception of Risk, Fear,

Instinct (Gut Feeling)Subjective

Norms

Worksite Compliance and Safety Culture

Behavioral Intentions

Evacuation Behaviors

Outcomes

Individual and Organizational

FactorsInitiation

Group Behaviors

Environmental Enabling Factors Progression

Final Destination

Initiation and Length of Time

Injuries

Long Term

HealthSensory

Cues

Major Study Outcomes

1. Length of time to initiate evacuation

2. Length of time to fully evacuate• Controlling for floor and elevator use (WTC

1 and 2)

3. Injuries (physical)

4. Long term health impact (physical and psychological)

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Quantitative DataDemographics

• Responses: 1767 total • Of these,1444 (82%) evacuated on 9/11/01* Demographics (N=1444):

• Gender: 58% male• Age, mean yrs: 44 yrs• Age, range: 22-80 yrs• Tenure, mean: 6 yrs• Tenure, range: 0-37 yrs• Marital status: 70% married/partner• Children: 48%• Race: 80% Caucasian• Education: 66% college+• Employment: 84% private company• Union membership: 7%

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Quantitative DataHealth Status

• Pre-existing disability or medical condition: 23%• Including…

• Respiratory: 28%• Mobility: 28%• Mental Health: 17%• Heart Condition: 16%• General Medicine: 7%• Sensory Deficit: 6%• Smoking: 19%

• 29% of those with a disability/medical condition said their disability affected their ability to walk down large number of stairs

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Quantitative DataKnowledge

• Knowledge Related to Preparedness (10 Questions)

• Mean 3.4• Median 3.0• Mode 2.0• Range 0-10

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10.009.008.007.006.005.004.003.002.001.000.00

Emergency Preparedness/Knowledge/Experience

140

120

100

80

60

40

20

0

Fre

qu

ency

Emergency Preparedness/Knowledge/Experience (alpha = .77)

Mean = 3.42, Median = 3.00, Mode = 2.00, SD = 2.41

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Quantitative Data

• Building Participants DID NOT KNOW:

89%

73%70%

59%

51%

26% 25%

3 Sta

irwells

Exit lo

cations

Doors o

n certain

floors

were lo

cked

Where

stairs

would

lead

Where

sky lobbies w

ere

locate

d

Thought roof m

ight b

e

means o

f escape

Not sure

about roof

Quantitative Data Lack of Familiarity with Building

• 56% somewhat familiar• 22% slightly/not at all familiar• 50% did NOT know enough about building to

leave on their own• 27% had evacuated the building at least once• 16% reluctant to evacuate

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Disability Preparedness Scale (alpha = 0.76)

Mean = 0.32

Median = 0.00

Mode = 0.00

Range = 0- 4

Quantitative DataPreparedness for Persons with

Disabilities

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Quantitative DataPreparedness for Persons with Disabilities

28% reported having a person with a disability on their floor

11% said a plan for evacuation of persons with disabilities was in place

10% said co-workers were assigned to assist persons with disabilities

8% said there was special equipment for the evacuation of persons with disabilities

5% said there was a designated area for persons with disabilities to gather

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Quantitative DataEmergency Preparedness

• Workplace Preparedness for Emergencies

(8 questions)

• Mean 2.8• Median 3.0• Mode 3.0• Range 0-8

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WTC Results onEmergency Preparedness Safety Climate

Emergency Preparedness Safety Climate: 8-items mean 2.83, med 3.0, mode 3.0

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Were NEVER PROVIDED with written fire safety instructions

NEVER PROVIDED with evacuation plans

Reported NO PLANS regarding where to gather after evacuating

NO PLANS for head count

WERE NOT familiar with who was in charge

Had NEVER exited the building as part of a drill

Had participated in fire drills, but of these, ONLY 11% HAD EVER ENTERED A STAIRWELL

Outcomes

• Initiation of start time• Length of time to descend/controlled by floor

and elevator use• Injuries (physical)• Long term health impact (physical and

psychological)

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Quantitative Data Key Time Periods

WTC1 WTC2

range range

• First became aware 8:46-9:20 8:46-9:02

• Made decision to leave 8:46-9:30 8:46-9:30• Began to leave 8:46-9:30 8:46-9:30• Reached street level 8:46-10:28 8:46-9:58

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8:00 a.m. 8:46 a.m. 8:55 a.m. 9:02 a.m. 9:59 a.m. 10:28 a.m. 11:00 a.m.

Tower 1 (North) impact

Announcement heard in Tower 2 (South)

Tower 2 (South) impact

Tower 2 (South) collapses

Tower 1 (North) collapses

Study OutcomesLength of Time to Initiate*

Evacuation(N=1444)

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Mean Minimum Maximum

WTC 1 6 minutes 1 minute 44 minutes

WTC 2 6 minutes 1 minute 44 minutes

* Start of Evacuation - First Awareness

Delaying Activities

Once they decided to leave, but BEFORE they began to…

• Gathering items (40%)• Seeking out friends/co-workers (33%)• Searching for any others (26%)• Making phone calls (18%)• Shutting down/PC-related (8%)• Waiting for direction (7%)• Gathering safety equipment (5%)• Changing shoes (3%)• Trying to obtain permission to leave (1%)

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Factors Significantly* Associated with Initiation

Individual- Age (O.R. = 1.4)- Delaying activities (O.R. = 3.1)- Disabilities/medical conditions- Hesitating (O.R. = 3.7)- Injuries (O.R. = 1.4)- Looking for groups (O.R. = 1.5)

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- Management- Military/first responders- Participation in drills- Poor knowledge- Sensory input- Smoking

* p< .05 OR = Odds Ratio

Quantitative DataSources of Communication

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• Obtained info from:– Face-to-face communications (42%)– PA announcement (12%)– Telephone (7%)– Cell phone (7%)– Television (7%)– Radio (4%)– Blackberry (4%)– Computer (2%)

Factors Significantly* Associated with Initiation

Organizational- Difficulty locating exits (O.R. = 2.0)- Lack of leaders- Emergency preparedness safety climate ↑

- (O.R. = 3.3); (WTC 1)- (O.R. = 2.4); (WTC 2)

Structural/Environmental- Poor signage (O.R. = 3.3)- PA Announcement (Tower 2)

36* p< .05

Quantitative Data Outcomes: Length of Time to Descend

WTC 1Mean: 42 minutes Rate*: 59 Seconds/floorRange:1-96 minutes

WTC 2Mean: 27 minutes Rate*: 31 Seconds/floorRange: 0-70 minutes

* Controlling for floor/elevator use 37

Significant* Factors Associated with Length of Time

Individual• Disability/medical condition (O.R. = 1.7)• Injuries (O.R. = 1.9)• Seriousness (O.R. = 1.8)• Stopping (O.R. = 3.3.)

OrganizationalEmergency preparedness safety climate ↑ (O.R. = 2.3)

Structural• Any adverse environmental condition (O.R. = 4.6)• Any damage (O.R. = 2.3)• Multiple sources of communication• Overcrowding on stairs or in lobbies (O.R. = 2.2)

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Quantitative Data Outcomes: Injuries/Long Term Health

• Physical Injuries: 37% (n=530)

• Surface Trauma 12% (n=172)• Inhalation Injury 11% (n=164)• Orthopedic Injury 7% (n=104)• Eye injury 4% (n=60)• General Trauma 4% (n=51)

• Psychological Injuries: 25% (n=357)

• Severity:• 63% sought medical care• 7% were hospitalized

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Significant* Factors Associated with Injuries

• Disability/Medical condition (O.R. = 2.0)• Fear for employment (O.R. = 4.9)• Female gender (O.R. = 1.9)• Lack of familiarity (O.R. = 2.7)• Less participation in drills• Not feeling personally responsible for own safety• Physical capability was low (O.R. = 2.8)• Starting from higher floor• Stopping• Supervisor would not approve (O.R. = 6.4)• Unsure of stairs

40*p < .05

Significant* Factors Associated with Injuries

• Any environmental condition• Any structural damage• Difficulty in following stairway route• Inadequate training • Lack of emergency preparedness• Making phone calls• Multiple sources of communication• Problem with shoes (O.R. = 2.6)

41*p < .05

Study Outcomes Long Term Injury Patterns

Condition n

Mental Health 132

Respiratory 61

Orthopedic 30

Medical 18

Cardiac 5

Vision / Hearing 5

• 221 persons (15.4%) of the evacuees reported at least one long-term injury related to evacuation of the WTC on 9/11 (some reported more than one condition).

• Long-term mental health problems were most common.

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Lessons LearnedFrom Evacuees

• Staying calm (“Behaving”)• Instincts• Mutual support• Leadership (group)• Directions/encouragement of first responders/NY/NJ

Port Authority• Integrity and condition of stairwells• General lack of massive overcrowding on stairwells

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Lessons Learned from the WTC Evacuation Study

• Human behaviors in this high rise fire were as predicted – Design features that support these behaviors will be

most effective • Training and drilling improve competency

– These should be mandatory • EP safety climate was associated with reduced

evacuation times, injuries and long term mental health problems.– EP Best practices should be implemented in all high

rise work settings

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Most Important Lesson Learned

• EMERGENCY PREPAREDNESS=RESILIENCY

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Regulatory Risk Reduction Strategies

1. NYC high-rise fire safety codes: Emergency Action Plan §6-02– EAP must specify the procedures for:

• Sheltering in-place• In-building relocation• Partial evacuation• Full evacuation

– Pre-planning for persons with disabilities

2. Designation and certification of an Emergency Action Plan Director (EAPD) §9-08– EAPD has the authority to implement this in the absence of

lawful authorities (i.e., they become the incident commander)

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Lessons Learned…and Implemented

• 2002: OSHA Compliance Document- Emergency Action Plans

• 2003: Society for Fire Protection Engineers Guide: Human Behavior in Fires

• 2005: NIOSH: Emergency Preparedness for Businesses

• 2005: FEMA Emergency Management Guide for Businesses

• 2007: NFPA Std on Disaster/Emergency Preparedness Management

• 2007: NFPA 101 Life Safety Code

• GAPS: ARE HIGH RISE BUSINESS OCCUPANCIES COMPLYING?? Public Assembly Places???

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Tribute in Lights

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Freedom Tower 9/11/11

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Robyn R.M. GershonDepartment of Epidemiology and Biostatistics Philip R. Lee Institute for Health Policy Studies

School of Medicine, University of California, San FranciscoRobyn.Gershon@ucsf.edu

415-476-1890

References

• Sherman MF, Peyrot M, Magda LA, Gershon RRM. Modeling pre-evacuation delay by evacuees in World Trade Center Towers 1 and 2 on September 11th, 2001: A revisit using regression analysis. Fire Safety Journal. 2011; 46(7) 414-424.

• Gershon RRM, Magda LA, Riley HEM, Sherman MR. The World Trade Center evacuation study: factors associated with initiation and length of time for evacuation. Fire and Materials. February 2011. doi:10.1002/fam.1080.

• Gill KB*, Gershon RRM. Disaster mental health training programs in NYC following September 11, 2001. Disasters. 2010;34(3). doi:10.1111/j.1467-7717.2010.01159.x

• Gershon RRM, Rubin MS, Qureshi KA, Canton AN, Matzner FJ. Participatory action research methodology in disaster research: results from the World Trade Center evacuation study. Disaster Medicine and Public Health Preparedness. 2008; 2(3):142-149.

• Qureshi KA, Gershon RRM, Smailes E, Raveis V, Murphy B, Matzner F, Fleischman A. A roadmap for the protection of disaster research participants: findings from the WTC evacuation study. Prehospital and Disaster Medicine. 2007; 22(6):484-49.

• Gershon RRM, Qureshi KA, Rubin MS, Raveis VH. Factors associated with high-rise evacuation: qualitative results from the World Trade Center Evacuation study. Prehosp Disaster Med. 2007; 22(3):165-173.

• Gershon RRM, Gemson DH, Qureshi K*, McCollum MC. Terrorism preparedness training for occupational health professionals. J Occup Environ Med. 2004;46(12):1204-1209.

• Nandi A, Galea S, Tracey M, Ahern J*, Resnick H, Gershon RRM, Vlahov D. The effects of job loss, unemployment, work stress, and work satisfaction on the persistence of probable PTSD: results from a cohort study of New York City metropolitan area residents one year after the September 11 attacks. J Occup Environ Med. 2004;46(10):1057-1064.

• Gershon RRM, Hogan E, Qureshi KA*, Doll L. Preliminary results from the World Trade Center evacuation study-New York City, 2003. Morb Mortal Wkly Rep. 2004; 53(35):815-816. 51