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Impact of September 11
Attacks on Workers in the Vicinity of the World Trade Center
Centers for Disease Control and
Prevention, Morbidity and Mortality Weekly Report, September 11, 2002
Impact of September 11 Attacks on Workers
in the Vicinity of the World Trade Center --- New York City
In January 2002, CDC's National Institute for Occupational Safety and Health received
requests for Health Hazard Evaluations from labor unions representing workers employed in
buildings in the vicinity of the World Trade Center (WTC). Workers reported persistent
physical and mental health symptoms that they associated with exposures from the WTC
collapse and ensuing fires. To address these concerns, CDC conducted surveys of workers at
four workplaces in New York City (NYC), a high school (high school A) and college (college
A) near the WTC site, and a high school (comparison high school B) and college (comparison
college B) >5 miles from the WTC site to determine rates of physical and mental health
symptoms. This report summarizes the preliminary results of the employee surveys, which
indicated that workers employed near the WTC site had significantly higher rates of
physical and mental health symptoms than workers employed >5 miles from the site.
Intervention programs should be tailored to address the needs of these workers, and the
effectiveness of these programs should be evaluated. Further assessment is warranted to
describe the nature and extent of illness in specific working groups and individual
medical follow-up in those with persistent symptoms.
CDC conducted site visits and distributed self-administered questionnaires in January 2002
to staff at high school A (n=224) and comparison high school B (n=155), and in March 2002,
to staff at college A (n=374) and comparison college B (n=204). Teaching, administrative,
support, and noncontract staff were included in the survey. Respondents were asked about
work duties, mental health and physical symptoms after September 11, past medical history,
and activities related to events at the time of the WTC terrorist attacks.
Questions about physical symptoms were based on presumed types of exposures and employee
concerns. Persons responding affirmatively to "Have you had any of the following
symptoms after the WTC disaster on 9/11/01?" were defined as having symptoms.
Physical symptoms included eye irritation, nose/throat irritation, cough, shortness of
breath, chest tightness, wheezing, nausea, and indigestion. Persistent physical symptoms
were defined as either 1) symptoms that existed before September 11 but worsened after
September 11, or 2) new symptoms that developed after September 11 and had not improved.
To assess mental health symptoms, the Center for Epidemiologic Studies Depression Scale
(1) was used to define symptoms consistent with major depression. The Veteran's
Administration post-traumatic stress disorder (PTSD) checklist (2) was used to determine
prevalence of PTSD.
Participation rates were 83% for high school A, 84% for high school B, 59% for college A,
and 50% for college B. Staff at all four workplaces were similar by age, sex, race,
education, and cigarette smoking status.
On September 11, approximately 40% of high school A and 31% of college A staff saw an
airplane crash into the WTC; 50% and 44%, respectively, witnessed the WTC collapse. In all
four workplaces, 30%--40% of the respondents knew someone who was injured seriously or
killed during the disaster. College A reopened for staff on September 26, and high school
A staff returned to their building on October 20. Both buildings were within two blocks of
the still burning WTC site and adjacent to a barge operation carrying the debris to the
landfill site outside Manhattan.
Approximately one fourth (27%) of staff at high school A and college A lost time from work
because of physical symptoms experienced after the WTC disaster, compared with 14% at high
school B (p<0.003) and 16% at college B (p<0.004). Compared with staff at high
school B and college B, staff at high school A and college A reported a significantly
higher prevalence ratio of new physician-diagnosed PTSD after September 11, but rates for
allergies, asthma, and depression were not statistically different.
Prevalence of eye irritation, nose/throat irritation, cough, nausea, and shortness of
breath was significantly higher (p<0.05) for staff at high school A and college A,
compared with staff at high school B and college B after September 11 (Table 1).
Approximately 4--6 months after the attacks, 5%--30% of employees in high school A and
college A had persistent physical symptoms (Table 2); the majority of these symptoms were
significantly higher (p<0.05) in high school A and college A than in the comparison
Approximately one third (33%) of high school A and 24% of college A respondents reported
symptoms consistent with major depression; 23% of high school A and 15% of college A
respondents had symptoms consistent with PTSD. Rates for symptoms consistent with
depression and PTSD from the survey were significantly higher in high school A and college
A compared with high school B and college B (Table 2).
Reported by: BP Bernard, MD, SL Baron, MD, CA Mueller, MS, RJ Driscoll, PhD, LC Tapp, MD,
KM Wallingford, MS, AL Tepper, PhD, National Institute for Occupational Safety and Health,
The findings from these surveys indicate that 4--6 months after the September 11 terrorist
attacks, workers surveyed near the WTC site had substantial rates of irritative,
respiratory, and mental health symptoms and lost work time, compared with similar workers
surveyed >5 miles from the WTC site. These findings indicate how the impact of the WTC
attacks extended beyond the WTC site to affect the health of persons working nearby.
Mucous membrane and respiratory symptoms among the survey participants described in this
report, the majority of whom were present during the September 11 attacks, might have
resulted initially from exposure to multiple environmental contaminants (e.g., smoke,
respirable airborne particles, fine dust, and fire combustion products) generated by the
collapse of the towers and ensuing fires. Information is limited concerning health effects
associated with complex mixed environmental exposures (e.g., those that occurred during
and after the WTC attacks).
Approximately 30% of workers included in this survey reported persistent physical symptoms
several months after the initial event. The persistence of symptoms in certain persons
might be explained by several factors, including differences in the initial exposure,
individual susceptibility, existing medical conditions, and factors related to social
support or individual stressors.
The results reported here indicate that many high school and college workers near the WTC
site experienced symptoms consistent with PTSD and depression. Proximity to the WTC site
also was a significant finding for "probable PTSD" (a slightly different case
definition using the same PTSD scale) among NYC residents in a recent web-based
epidemiologic study (4).
The findings in this report are subject to at least two limitations. First, responses to
extraordinary traumatic events might provoke a range of reactions, and symptoms alone are
not adequate to document fully psychologic or physical illness. Second, because of the low
response rate for colleges A and B, the percentages and prevalence ratios should be
interpreted with caution because of potential participation bias.
Further investigations using full clinical diagnostic assessment might be useful in
determining the breadth and scope of illness in persons with persistent symptoms. Because
mental health and physical symptoms can persist for extended periods after a disaster,
persons who continue to experience symptoms should seek professional assistance.
Counseling services should continue to target those who are vulnerable to depression and
PTSD, particularly those who have lost family or friends, those who do not have a social
network, and those who witnessed the attacks (5,6).
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population. Applied Psychological Measures 1977;1: 385--401.
Weathers FW, Litz BT, Herman DS, Huska JA, Keane TM. The PTSD checklist: reliability,
validity, and diagnostic utility. Paper presented at Annual Conference of the
International Society for Traumatic Studies: San Antonio, Texas: International Society for
Traumatic Studies, October 25, 1993.
American Psychiatric Association. The diagnostic and statistical manual of mental
disorders-IV (DSM-IV), 4th ed. Washington, DC: American Psychiatric Association, 1994.
Available at http://www.appi.org.
Schlenger WE, Caddell JM, Ebert L, et al. Psychological reactions to terrorist attacks.
Goenjian AK, Molina L, Steinberg AM, et al. Posttraumatic stress and depressive reactions
among Nicaraguan adolescents after Hurricane Mitch. Am J Psychiatry 2001;158:788--94.
Mazure CM, Bruce MI, Maciejewski PK, Jacobs SC. Adverse life events and
cognitive-personality characteristics in the prediction of major depression and
antidepressant response. Am J Psych 2000;157: 896--903.
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