Prof will study flu risk

10/18/2006
By From the Nashua Telegraph

Column by David Brooks

Here’s a bit of potential medical irony:

Research into slowing the spread of flu during a pandemic, part of a hunt for something better than the discredited idea of wearing surgical masks in public, just might find that . . . drum roll, please . . . we should wear surgical masks in public.

Or it might not ߝ you never can tell with research (at least, not with good research). But that’s one highly intriguing possibility that may come out of research by Dr. Don Milton of UMass-Lowell, who just received a $550,000, two-year federal grant to study ways to keep coughing, sneezing folks from spreading virus-laden droplets through the air.

Anticipating such an intriguing result is getting ahead of ourselves, says Milton, because it will be a non-trivial exercise to show whether such masks actually make a difference ߝ starting with making measurements about what icky stuff is breathed out by sick people.

“We’re trying a variety of things. Initially, we’ll probably have people breathe into a tube. But the plan is to build something . . . where basically, people will sit inside a little tent, and we’ll be sampling the air as they breathe, eliminating background contamination,” he said.

“The logistics are not easy. This is a two-year project, which is pretty fast turnaround.”

Not easy at all. The average person breathes around 10 cubic meters of air a day, which is a lot. Sampling that for floating viruses, then capturing and culturing any viruses to see what they are, then determining whether dangerous viruses would remain airborne long enough to be a risk to other people ߝ and doing this with enough people to be statistically significant . . . suddenly two years doesn’t sound like much.

Milton, a physician, is also adjunct senior lecturer at Harvard School of Public Health as well as a professor of work environment at Lowell. His grant is one of eight given out by the Centers for Disease Control & Prevention to study non-pharmaceutical ways to prevent the spread of flu if it should reach pandemic stage.

Milton is involved because his specialty is aerobiology, a field that studies organic particles carried passively through the air.

It’s a field with a pretty high yuck potential, because those particles are often carried on mucus. Milton didn’t quite chuckle, but I think he came close, when he heard my reaction to “ballistic droplets,” his term for the relatively large blobs of moisture sprayed by folks with over-energetic sneezes.

Yuckiness aside, what about the mask question?

Public health officials have long known that wearing surgical masks in public, the way people did during the influenza epidemic of 1917, doesn’t really protect you from other people’s flu because the airborne moisture carrying viruses is small enough (less than 5 microns, or millionths of a meter, in diameter) to slip through the mesh.

Milton, however, notes that virus-laden droplets ߝ “ballistic” or otherwise ߝ dry up quickly, which means when they’re first sneezed they’re bigger, by some unknown quantity, than when they make it over to another person.

It’s possible, Milton said, that when you sneeze these droplets, they’re too big to fit through a mask, even though they can fit after they’ve floated through the air and dried up a bit. The question is, how big are they at first?

“Were they 10 microns? At what point were they 10 microns? . . . How fast do they dry out?” he said. “These are questions that you’d think people would have thought about and answered, but it turns out they haven’t.”

So Milton’s work will perform that most basic and important of scientific tasks, measuring something accurately. If our virus-carrying droplets are big enough as they leave our mouths, then wearing masks in public during a pandemic is a good idea after all, but for the opposite reason than once thought: They wouldn’t protect you from other people, they would protect other people from you.

“If so, it becomes a really interesting moral dilemma,” mused Milton. “What if there’s a pandemic and people are riding a bus, and you see somebody trying to board who isn’t wearing a mask. What should you do?”

It’s also exactly the kind of information the government needs to know to make decisions about how to slow a pandemic.

Should they stockpile 50 million surgical masks, or not? Gather as much relevant scientific evidence as have time to buy, then decide. If only all public policy worked that way.