<p>More than half of the New York City Fire Department firefighters who developed what has been dubbed "World Trade Center cough" have not returned to active duty, according to reports out Monday.</p>
<p>In the six months after the World Trade Center attacks, the eponymous ailment — defined as a cough severe enough to require at least four weeks of medical leave — occurred to 332 firefighters and one emergency medical services worker, says David Prezant, the fire department's deputy chief medical officer.</p>