What's in a number?

The 9/11 memorial has been open 16 weeks and has already has had a million visitors. The memorial opened on the 10th anniversary of the tragic destruction of the twin towers.

On the memorial's bronze plates, surrounding the plunging fountains, are the names of the 2,751 killed in the collapse of the towers -- brought to a total of 3,000 people killed in the 2001 attacks, plus the six who died from the earlier 1993 attack, when a truck bomb was detonated in the parking garage under the former towers.

The number of workers who have registered with hospitals in ground zero programs is now 37,000 and going up about 500 individuals a month, according to a 2007 National Institutes of Health report. According to a September report by CBS, 15,000 ground-zero workers now get treated for chronic disease like sinusitis, GERD, rhinitis and worse. About 1,600 people at present have lawsuits related to health issues from working at the site, and federal lawmakers, with the Zadroga Act, have allotted $2.6 billion for coverage of those who get sick from the exposure to the toxic brew in the smoke and ash of the collapsed buildings, according to AP. However, the deadline to be part of that act's fund is Jan. 2, 2012 . That's when those 1,600 must decide if they want to be compensated and cared for by that fund, or if they want to keep their lawsuits going. The choice is made far worse by the fact that the fund is still determining which illnesses are 9/11 related. Beyond that, it will probably be six years before any money will come to the victims -- cancer is not one of the illnesses covered.

So if you get cancer from the toxins in the smoking rubble of the towers, your health expenses may not be covered. What are the odds. Again, numbers.

Life is reduced to a series of numbers. 9/11, 1/2/12...3,000...1,600...

There is an old saying about numbers. Lies, damned lies and statistics. I think about that time a decade ago, when those I loved, for example, who have not registered for this fund, emerged from the Fulton Street subway stop into shin-deep ash, who walked through the cloud passing people with broken arms that had bones protruding, covered with soot and debris. Was that the day they took a dose of poison into their bodies that they will pay a health-price for someday? How long? How much? What's the number of molecules of toxin it takes to reach a damaging dose? And how long before the effects are known?

Then there are my friends who lived downtown. They were in the swirling dust for days, maybe weeks, maybe forever, from sidewalks and rooftops, all but invisible, but lingering on in nooks and crannies. Some have developed respiratory illnesses or cancers since then. Of course, those might be unrelated. I am sure of it. Statistically, what are the odds? What's the number? We will never know.

Were a million people exposed to the toxins that day? I remember seeing photos of the plume from space as it stretched far and wide. It engulfed downtown but also spread far and wide. Do we have a number for that? A number of meters or miles away that was safe. Or a number of parts per million in the air that made it safe? Was that just a million people exposed to those toxins? Was it tens of millions? Will we ever find out the number of cancers, lung problems, autoimmune diseases and other ailments brought on by that single act of terrorism. An act whose number is just one?

More numbers. Numbers we will never know.

We will never know the full extent of the health effects that day. For an unlucky few, mostly the closest and the bravest, the first responders and the workers who toiled in the smoldering pit for what seemed like forever, the toll on their health is clear, or clearer, than for the hundreds of thousands or millions of New Yorkers and others in the region as a whole exposed at close range and then later for months, if not years.

It will just be forever a cloud, not just 10 years after, for a generation from now. How many generations? Even that we will never know.

What we do know is that a million have come to pay their respects. And that millions more will come as the years go by. The number who come to bear witness to a terrible, sad time, which is a number we can know.

Follow Tom Dworetzky and IBTNewYork on Twitter