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What We Know About the Health Impacts of 9-11
  By the NYC Health Commissioner
  More About Physical Health
  More About Mental Health
  Current Studies
  9/11-Affected People
  Healthcare Professionals


9/11 Health - What We Know

A Message from the Commissioner of the New York City Department of Health and Mental Hygiene

Millions of people were affected by the September 11 terrorist attacks — from physical and mental health problems to financial loss. This large and diverse population had different exposures after the collapse of the World Trade Center (WTC), and health effects have varied as a result.

More than a decade of studies suggest that while the majority of people exposed to the WTC disaster are healthy and symptom free, thousands of individuals—including rescue, recovery and clean-up workers and people who lived, worked or went to school in Lower Manhattan on 9/11—have developed chronic, and often co-occurring, mental and physical health conditions.


What We Know

Mental Health

  • Large epidemiological studies conducted by the Health Department’s WTC Health Registry suggest that post-traumatic stress disorder (PTSD) symptoms are the most common health effect of 9/11. Experienced by as many as 20% of adults who were directly exposed to the WTC disaster, this is roughly four times the rate of PTSD symptoms typically found in the general population.

    Risk factors for probable PTSD included:
    • Intense dust cloud exposure or suffering an injury on 9/11
    • Being on a high floor of the World Trade Center, evacuating late or working for an employer that sustained fatalities.
    • Witnessing horror or knowing someone killed or injured on 9/11
    • Little or no social support after 9/11
    • Respiratory illness
  • Rescue and recovery workers who started rescue work on or soon after 9/11 or who worked at the WTC site for a long time were also more likely to develop PTSD. Workers from non-emergency occupations also suffered higher rates of PTSD than emergency responders
  • People who experienced trauma before or after 9/11, such as losing a job after the attacks, or urban or domestic violence, were at increased risk for developing PTSD.
  • Despite widespread evidence of PTSD among all exposed groups, studies have not shown an increase in suicide up to four years after 9/11.Depression, anxiety and substance use disorders have not been as well studied as PTSD among WTC-exposed people. The studies to date, however, suggest that the prevalence of these conditions increased shortly after 9/11, and for many people these conditions persist.  There is significant co-occurrence, or co-morbidity of other mental health symptoms, with PTSD in WTC-exposed groups.
  • A study using WTC Registry data found that five to six years after the attacks, those with the greatest exposure to the events of 9/11, and those with 9/11-related PTSD, were about twice as likely to binge drink. (Binge drinking is defined as consuming four to five drinks at a time).

Respiratory Illness

  • Those exposed to WTC-related dust were more likely to develop respiratory symptoms, sinus problems, asthma or lung problems. One in 10 Registry enrollees developed new-onset asthma within six years of 9/11, three times the national rate. New cases were highest during the first 16 months after 9/11.
  • Intense dust cloud exposure on 9/11 increased the risk of developing asthma. These groups were especially at risk:
    • Rescue, recovery and clean-up workers who arrived early at the WTC site or worked at the WTC site for long periods of time
    • Lower Manhattan residents who didn't evacuate their homes
    • Lower Manhattan residents and office workers who returned to homes or workplaces covered with a thick coating of dust
    • People who both lived and worked in lower Manhattan after 9/11
  • Steep declines in pulmonary function first detected among firefighters and emergency medical service (EMS) workers within a year of 9/11 have largely persisted, even among those who never smoked. It is estimated that four times as many firefighters and twice as many EMS workers had below-normal lung function for their ages six to seven years after 9/11 as they did before the attacks. Among the few active smokers, pulmonary function declines were even greater than for non-smokers.
  • Studies also have identified persistent abnormal pulmonary function in other WTC rescue and recovery workers, including police, and in Lower Manhattan residents and area workers.
  • Seven to eight years after 9/11, continuing lower respiratory symptoms were identified in area workers and people living in Lower Manhattan at the time of the attack. The prevalence of symptoms correlated with the degree of WTC disaster exposure and abnormal pulmonary function.
  • Both epidemiologic and clinical studies demonstrate substantial co-morbidity (co-occurrence) of respiratory illness and mental health conditions in WTC-exposed groups.

Heart Disease

  • Those with multiple injuries sustained on 9/11 and 9/11-related PTSD had a three-fold higher risk of heart disease than those with no injury and no PTSD.
  • Although limited by small numbers, a study using hospital records similarly found that directly exposed male rescue and recovery workers were at increased risk for subsequent heart-related hospitalization. Those who were directly exposed but did not participate in rescue/recovery efforts were not found to be at increased risk. The study also suggested that 9/11-related PTSD increased the risk of being hospitalized for heart disease, consistent with existing studies on PTSD and heart disease.

Other Illnesses

  • Many WTC-exposed people report heartburn, acid reflux or other gastroesophageal reflux symptoms, often with respiratory or mental health symptoms. Since these symptoms are common among the general population, more research is needed to determine the connection between them and WTC exposure.
  • Several studies have suggested that WTC exposure is associated with sarcoidosis (an inflammation that can affect any organ, but typically affects the lungs) among rescue, recovery and clean-up workers who worked on the debris pile. However, these studies cannot rule out the possibility that increased medical attention and testing may be responsible for the detected increases in sarcoidosis rates among WTC workers.
  • A WTC Registry study of enrollees suggested that those with 9/11-related PTSD may be at slightly increased risk of developing diabetes, but more research is needed to confirm this finding.

Birth Outcomes and Childhood/Adolescent Health

  • Findings have been inconsistent regarding the impact of WTC exposure on birth outcomes. Some studies suggest that reduced fetal growth found in some babies delivered by women who were pregnant on 9/11 may be related to the stress caused by the attacks. Other studies, however, found no impact of WTC exposure on birth outcomes.
  • Few studies have addressed the impact of WTC exposure on child and adolescent health, especially physical health. Data from the WTC Health Registry's 2003-2004 survey of 3,000 children and adolescents indicate that very young children caught in the dust cloud on 9/11 were at increased risk for developing asthma. Six to seven years after 9/11, the Registry found that respiratory symptoms were associated with WTC exposures in younger children and with behavior problems in adolescents.


  • Although cancer takes many years, even decades, to develop, three early WTC cancer studies based on diagnoses confirmed through 2008 have been published. This research suggests that long-term monitoring of cancer occurrence among WTC-exposed individuals is warranted:
    • The New York City Fire Department (FDNY) found that nearly 9,000 firefighters with WTC exposure may be at greater risk for cancer than firefighters who weren’t exposed.
    • The WTC Registry focused on cancers occurring in 2007 and 2008 because they are more likely to be related to WTC exposure than earlier cancers. The Registry found small increases in rates of prostate cancer, thyroid cancer and multiple myeloma, a blood cancer, among nearly 34,000 WTC rescue and recovery workers in comparison to New York State residents after adjusting for age, race/ethnicity and sex. No increases were found during the same time period among Lower Manhattan residents, area workers and students enrolled in the Registry.
    • The WTC Health Program found higher-than-expected prostate and thyroid cancer rates among nearly 21,000 rescue and recovery workers enrolled in the Program, compared to overall rates in New York, New Jersey, Connecticut and Pennsylvania, where the majority of workers lived.


  • The only WTC-related mortality study to be published showed that WTC Registry enrollees were less likely to die in the eight years of follow-up than people in the general New York City population. However, the study also showed that among Lower Manhattan residents, area workers and passersby in the Registry, those with higher levels of WTC exposure may be at greater risk for all-cause mortality and cardiac-related mortality, especially compared to people with intermediate or lower levels of WTC exposure.



What Additional Research Can Tell Us

Further studies would grow our understanding of these issues:

  • The full extent and persistence of known WTC-related health conditions, as well as potential new emerging conditions
  • The extent to which people with potential WTC-related health conditions are receiving treatment, and what coverage gaps remain
  • The effectiveness of treatment for patients with WTC-related mental and physical health conditions
  • Whether or not findings from early cancer and mortality studies are replicated, if they are replicated in different populations with different exposure levels, and if they change over time
  • The role WTC-related illness may play in cardiac disease and diabetes
  • How prevalent WTC-related depression and substance use are among WTC-exposed populations
  • The impact of ongoing WTC-related physical health conditions on long-term mental health
  • The long-term impact of 9/11 on children who went to school or lived in the area, whose parents were part of the rescue and recovery effort or who lost family members
  • The health impact of subsequent disasters and events, such as Hurricane Sandy, on people with 9/11-related conditions, including PTSD

The WTC Health Registry completed its third health survey of more than 68,000 adult enrollees and more than 1,300 adolescents and their parents in September 2012. The Registry has begun planning its fourth health survey.


Monitoring and Treatment for 9/11-Related Health Conditions

No matter where they live now, people affected by 9/11 are eligible for treatment and medication with no out-of-pocket costs at the WTC Health Program. The Program includes New York City’s three Centers of Excellence and the National Provider Network.

The Centers and the WTC Health Registry—all funded by the federal government—continue to provide clinicians, epidemiologists and other researchers with the kind of evidence that, over time, will help answer some of the current unknowns. Their ongoing work will help better identify the people who are at greatest risk for becoming ill and further refine treatment options for people who already are sick.


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