For millions of people, Sept. 11, 2001, was the first mass disaster experienced in real time. Many who watched the event unfold on television can still remember with great clarity, as the 15th anniversary approaches, where they were, and how they felt, on that terrible day.
I was in New York City on 9/11, just starting my career as an epidemiologist. Along with countless other New Yorkers, I watched with horror as the World Trade Center towers collapsed. Stunned by the destruction, our research team quickly became concerned with the potential long-term mental health consequences of the attacks.
Working with colleagues across the country, we designed a series of studies aimed at documenting the mental health effects of 9/11. The first study, conducted a month after the tragedy, suggested that large-scale terrorist attacks can pose health challenges even for populations not directly exposed to such events. We estimated that about 7.5 percent of Manhattan residents had post-traumatic stress disorder, and 9.7 percent had depression that first month, for a total of about 67,000 people with PTSD and 87,000 with depression in Manhattan alone. We then studied residents in the entire New York City metropolitan area and found a substantial burden of PTSD and depression throughout the region.
Other scientific work followed, with researchers finding strong associations between exposure and mental illness — including substance abuse — and respiratory illness, particularly among rescue and recovery workers.
We now understand what happens to the health of populations after large-scale disasters much more clearly than we did in 2001. However, the seemingly interminable string of terrorist attacks worldwide remains a sad and insistent reminder of the need for more work in this area. In moving forward, we can build on three key lessons learned so far.
First, we must expect that the consequences of these events will be pervasive, threatening not only the immediate victims of disaster, but larger populations. As our research has shown, the health hazards of 9/11 affected many, beyond just those who were in or near the twin towers. Subsequent research about other large-scale events, including Hurricane Katrina and the 2005 bombings in the United Kingdom, have confirmed and extended what we learned after 9/11: that large-scale terrorist attacks or disasters can change the trajectory of population health for decades after the initial catastrophe. This means we must invest in strong community infrastructures and in responsive, flexible health systems that can manage these long-term effects in the months and years after disasters occur.
Second, we need to acknowledge that the consequences of traumatic events extend well beyond physical harm. Standard accounts of 9/11 suggest that 6,000 people were injured in the attacks, which killed nearly 3,000 people. But we know that in the wake of these events behavioral illnesses such as PTSD and depression and the use of substances will affect far greater numbers.
Finally, in our focus on the horror and scale of disasters, we must not lose sight of the broader population health picture. The health outcomes of traumatic events are shaped by a complex set of factors that include underlying socioeconomic context, the race/ethnicity of those affected, and ongoing traumas and stressors, all of which influence well-being. When disaster strikes, the highest price is often paid by marginalized groups already at a disadvantage. This is because these groups frequently have less access to resources that could mitigate the consequences of traumatic events. After Hurricane Katrina, for example, the damage from the storm was compounded by poverty, racism, and an overwhelmed health care infrastructure. It is only through careful attention to the foundational drivers of population health that we will be able to cope effectively with the effects of terror attacks and disasters.
While many of us have moved on from the experiences of 9/11, thousands of others continue to live in the shadow of that day, with lingering emotional and physical wounds. The best way to honor the victims of the attacks is to resolve to build on what we have learned over the past 15 years about the consequences of mass trauma, and devise strategies to mitigate these consequences.
Sandro Galea is dean of Boston University School of Public Health.