Vermont's winter weather is unpredictable. But global warming notwithstanding, we can still usually count on a string of polar days when temperatures tumble well below zero. The sky is deep blue, but the air is as raw as a saw, cutting through every last layer. A few of us will still head outdoors anyway, for a run or a ski or a walk with the dog. People passing in cars will shake their heads; family members will express concern about frostbite and frozen lungs.
Just how healthy is it to exercise in the bitter cold Vermont air? "Look at ravens," suggests biologist and long-distance runner Bernd Heinrich, who wrote Winter World: The Ingenuity of Animal Survival. "They fly at minus 30 degrees." Compared to humans, "they are breathing harder and the length of warm tissue that air has to traverse is less," Heinrich points out, "so they're still breathing cold air and their lungs are not freezing up."
Though we don't have feathers, we do have beaks to facilitate our breathing. "We've got long noses to warm our air before it gets to the lungs," says Heinrich, who can't remember ever having trouble breathing while running in the cold. Whether the air we breathe is five degrees or 50 degrees Fahrenheit, the nose takes a quarter of a second to warm it to 98.6 degrees before it enters the lungs.
But what if it's, say, 40 below -- the otherworldly temperature when Fahrenheit and Centigrade numbers coincide? You still won't freeze your lungs. It's a good idea to breathe through a scarf or neck gaiter, though, Steven Bainbridge explains in a recent Runner's World story. The fabric will not only protect against frostbite, which is the real danger of icy days, but can also act as a filter to prevent a burn in the throat. The president of an Alaskan running club, Bainbridge has had plenty of below-zero experiences. The story later asserts that the only way to freeze your lungs is to die outdoors during the winter.
That said, cold air, especially when inhaled through the mouth, can create problems for the 11 percent of Americans who suffer from exercise-induced asthma, according to the American Academy of Allergy, Asthma and Immunology. Air that passes directly into the lungs through the mouth has a relative humidity of 60 to 70 percent, versus 80 to 90 percent humidity when it passes through the nose. When the cold, dry air hits the lungs, they respond by producing histamine, which can cause wheezing, chest pain, coughing and shortness of breath.
Even if we're asthma-free, we may be coughing as a result of another source that can intensify during bouts of cold weather: air pollution. "In winter, idling, especially heavy-duty diesel trucks, is a big issue," says Dick Valentinetti, director of Vermont's Air Pollution Control Division. Alarmed by the recent accumulation of health research on the effects of diesel emissions and very fine particulate, he and other pollution control officials are working on anti-idling legislation for heavy-duty trucks and school buses. These laws could be in place by mid-2005. Says Valentinetti, "We're the only state in the Northeast that does not have regulations in terms of smoking trucks."
Valentinetti is one of several clean-air crusaders referenced in a new book, Gasp: The Swift & Terrible Beauty of Air. The latest from Vermont author Joe Sherman was inspired in part by air-quality data he had amassed while writing about an electric-car entrepreneur. Sherman set out to capture an amorphous substance -- which could fill several encyclopedias --in a single volume. "I was interested in going from the mitochondria in your cells to where the edge of the atmosphere feathers off into the void," he says.
Tracing thousands of years of air use and abuse, Sherman sets out to find the cleanest air in our 21st-century world. "Wow, was I ever dreaming," he writes. "What exactly was clean air, anyway? ... Air contains thousands of trace elements, both natural and artificial ... Atmospheric chemists tell us that we normally breathe about 170 of the thousands of trace elements ... by just walking around outside the house."
The air outside houses in Chittenden County is cleaner than it is in most parts of the United States, at least when it comes to industrial air pollution and ozone. Punch in zip code 05401 at scorecard.org, and the Environmental Defense Website reveals that in 2002, Chittenden County ranked among the cleanest 10 percent of American counties in terms of recognized carcinogens such as lead and ethylene compounds. For ozone concentration, it was among the cleaner 30 percent.
The bad news is, the Burlington area ranks in the "dirtiest-worst" 30 percent when measuring an individual's added cancer risk from hazardous air pollutants. Though we have few "point sources" -- big, chemical-producing plants -- our roads are crowded with thousands of cars and trucks. Motor vehicles are substantial sources of such carcinogens as benzene, formaldehyde, acetaldehyde, 1,3-butadiene and diesel particulate matter. "Warming" up the car in cold weather results in longer running times and more toxins being released into the air.
Stoves and fireplaces emit smoke, too -- enough to cause concern among members of the American Lung Association. "In some localities, fireplaces and woodstoves have been identified as the source of 80 percent or more of all ambient particles smaller than 2.5 microns in diameter," its website warns. It goes on to link the presence of those particles with "adverse health outcomes... especially among those with preexisting cardiopulmonary illness."
How do we stay healthy this winter? Cross-country skiing is one good way to clear the air passages. At Huntington's Sleepy Hollow, there are additional pulmonary plusses. The machines that groom the trails are powered with vegetable oil. And anyone who arrives by hybrid car has the run of the place for free. m