Although it's eight years since 9/11 attacks happened, a study published on Wednesday has found that a large number of New York rescue workers involved in the relief work continue to suffer from lung damage due to exposure to World Trade Center dust.
The seven-year study of nearly 13,000 rescue workers from the New York Fire Department (FDNY), which included almost 62,000 individual measurements, is the largest ever longitudinal study of occupational impact on lung faction.
"This exposure at Ground Zero was so unique that no one could have predicted the impact on lung function," said David Prezant, the study's senior author and professor of medicine at New York's Albert Einstein College of Medicine of Yeshiva University.
For the study, published in The New England Journal of Medicine, researchers evaluated nearly 92 percent of the 13,954 FDNY firefighters and emergency workers present at the World Trade Center site between September 11 and September 24, 2001.
They used spirometry, which measures the amount of air exhaled in a single breath, every 12 to 18 months to assess lung function in 12,781 of the workers.
The researchers were able to measure declines in lung function thanks to spirometric results from the participants, who were also tested before 9/11.
A substantial proportion of the rescue workers suffered from severe and persistent lung function decline, and were left with abnormal lung function when the study ended on September 11, 2008.
Prezant and his team said it was critical to identify those individuals most affected and treat them.
The study came on the heels of previous research published in 2006 in the American Journal of Respiratory and Critical Care Medicine that evaluated lung function a year after the 9/11 attacks.
In that study, Prezant and his colleagues found that FDNY rescue workers suffered substantial loss of lung function during that period -- more than 12 times the decline in lung function that usually accompanies normal aging.
Those workers who arrived at the World Trade Center site the morning of the attacks, when the dust cloud was heaviest, suffered the most substantial lung damage.
For the current study, the proportion of workers who never smoked and whose lung function was nonetheless below normal jumped from three percent to 18 percent in the first year for firefighters and from 12 to 22 percent for emergency medical services workers.
Seven years after the attacks, the proportions stabilized at about 13 percent for firefighters and 22 percent for emergency workers.
"The workers in our study population experienced repeated daily exposures to much higher concentrations of airborne particulates and gaseous chemicals" than most other firefighters, said lead author Thomas Aldrich of Yeshiva University.
Aldrich said rescue workers may have struggled to recover in the long term because of the unusual nature of the World Trade Center dust, which was filled with pulverized material from the collapse of the Twin Towers, and due to smoke from fires that burned until mid-December in 2001.
"All smoke contains particulates, but not at the density seen in the WTC collapse, especially if you were at the site during the first two or three days or for long durations thereafter," he said.