WEDNESDAY, Sept. 10 (HealthDay News) -- Two to three years after the 9/11 terrorist attacks, psychological trauma and new respiratory problems were still elevated among people enrolled in the World Trade Center Health Registry, according to the latest New York City health department study.

Released on the eve of the seventh anniversary, the study looked at the health effects among all 71,437 participants of the registry, which includes rescue and recovery workers, lower Manhattan residents, area workers, commuters and passersby. Among the registrants: more than half reported being in the dust cloud from the collapsing World Trade Center towers; 70 percent witnessed a traumatic sight, such as a plane hitting a tower; and 13 percent suffered an injury on 9/11.

Those 71,437 people represent only about 17.4 percent of people whose exposure to the disaster would have made them eligible to enroll in the registry.

Two to three years after 9/11, 3 percent of all adult enrollees reported they'd developed new asthma, 16 percent had post-traumatic stress disorder (PTSD), and 8 percent had severe psychological distress, according to the study, published in the Journal of Urban Health.

Rescue and recovery workers who worked on the debris pile had the highest rate of new asthma (6 percent), while the PTSD rate was highest among injured (35 percent), low-income (31 percent) and Hispanic (30 percent) enrollees. Overall, minorities, people with low incomes, and women experienced higher rates of mental and physical problems.

Based on the figures from the registry, the study authors estimated that more than 400,000 people were exposed to the WTC disaster, 35,000 to 70,000 developed PTSD, and 3,800 to 12,600 people developed asthma as a result of the day's events.

The study found that 3 percent of Lower Manhattan adult residents and workers had developed asthma in the two to three years after 9/11 -- a rate believed to be twice the baseline rate of asthma development over that period. The asthma rate was 3.7 percent among residents who didn't evacuate on 9/11, 3.6 percent among residents who returned to their homes within two days, and 2 percent among those who didn't return home until December 2001.

High rates of asthma development were also noted among downtown workers who returned to their jobs within days of the disaster (3.5 percent) and passersby who were in Manhattan the morning of the attacks (3.6 percent).

The high asthma rates among these groups are similar to those previously published for rescue and recovery workers/volunteers.

The study also found PTSD rates of 20 percent or higher for residents and workers who couldn't or wouldn't return to lower Manhattan for months after 9/11 and for people who didn't evacuate. The finding isn't surprising, because people with PTSD tend to avoid the site of their traumatic experience, the study authors explained.

"These data show that rescue and recovery workers were not the only groups affected. Living and working near the WTC site also put people at risk of health problems," Dr. Mark Farfel, director of the World Trade Center Health Registry, said in an NYC health department news release.

"The health impact of 9/11 reached far beyond the deaths and injuries that occurred that day," Lorna Thorpe, the health department's deputy commissioner for epidemiology, added in the news release. "But many of the health issues that have emerged, such as asthma and PTSD, are treatable. Free treatment is available. Anyone still in need of help should ... visit nyc.gov."

More information

Here's where you can find the World Trade Center Health Registry.