This is the VOA Special English Health Report.

Many of the workers who served at the World Trade Center after the September 11 attacks became sick. They breathed a harmful mix of dust, smoke and chemicals in the ruins of the Twin Towers and a third building that fell. Some went days without good protection for their lungs.

Five years later, many of the thousands who worked at Ground Zero in the early days after the attacks still have health problems.

Doctors at Mount Sinai Medical Center in New York City have announced the results of the largest study yet of these workers. The results appeared last week in Environmental Health Perspectives, the journal of the National Institute of Environmental Health Sciences. The study is called the World Trade Center Worker and Volunteer Medical Screening Program.

It confirmed high rates of breathing problems in members of the building trades, firefighters, police officers and other workers.

Almost seventy percent of the workers in the study had a new or worsened breathing problem. These problems developed during or after their time working in the mountain of wreckage. About 60 percent still had breathing problems at the time of their examination.

The researchers say they decided to study the effects on breathing first because other disorders might be slower to appear.

Mount Sinai says it tested almost 12,000 people between 2002 and 2004. Eight out of ten of them agreed to have their results used in the report.

The new results added strength to a Mount Sinai study released in 2004. That study was based on only about 1,000 workers.

Some lawmakers have sharply criticized city and state officials for letting workers labor at Ground Zero without satisfactory equipment. Officials have also been criticized for saying the air was relatively safe.

State and federal officials have promised more than 50 million dollars to pay for treatment of the workers. Doctor Robin Herbert is one of the directors of the Mount Sinai testing program. She says people are still coming to the hospital for treatment of problems they say were caused by the dust at Ground Zero. In her words: "My worry is that money will be gone in a year, and what happens then?"

And that's the VOA Special English Health Report, written by Jerilyn Watson. You can find more reports on the fifth anniversary of the September eleventh attacks at www.unsv.com. I'm Mario Ritter.