EarthTalk: Inflating Car Tires & Fire Pits

Dear EarthTalk: Is using nitrogen to inflate my car’s tires really better for the environment than using air? And if so, how? -- Roger Mawdsley, Abbotsville, BC

Whether or not it makes environmental sense to inflate car tires with nitrogen instead of air is a matter of much debate. Proponents of nitrogen say the element is a smart choice for the environment primarily because it leaks from tires at a slower rate than air, so tires stay inflated longer at full capacity, which helps a vehicle attain maximum fuel efficiency, i.e. better gas mileage. According to the Get Nitrogen Institute, a Denver-based non-profit which advocates for replacing the air in our tires with nitrogen, under-inflated tires inadvertently are a big contributor to global warming as they cause drivers to waste fuel.

Although auto experts recommend checking your car’s tire pressure weekly, studies show that the majority of drivers rarely if ever check to see if their tires are properly inflated and usually only add air when a tire is visibly low or beginning to go flat. A recent study by the European division of tire maker Bridgestone found that 93.5 percent of cars in Europe have under-inflated tires, wasting some 2.14 billion gallons of high-priced, polluting fuel every year. Analysts believe that a similar percentage of North Americans are driving around on under-inflated tires as well.

While properly inflated tires certainly promote better fuel efficiency and are thus good for the environment, not everyone is convinced that filling tires with nitrogen instead of plain ol’ air makes a difference. Terry Jackson, who writes the influential “Driving for Dollars” column for the Bankrate.com website, points out that air is composed primarily of, you guessed it, nitrogen; some 78 percent of the regular air you put in your tires is nitrogen, with oxygen making up most of the remainder. “So going to pure nitrogen only squeezes out a small amount of the oxygen molecules that nitrogen proponents argue are so detrimental,” relates Jackson.

Nitrogen proponents may quibble that it’s the oxygen in the mix that causes problems, though, as oxidization can start to degrade the rubber inside tires while corroding the interior of the wheels as well. But Jackson counters that tires and wheels will have been long worn out on the outside before any oxygen-induced interior damage causes them to come apart. Also, he adds that a lot of the leakage from tires happens because the wheel and the tire do not line up perfectly, and air (or nitrogen) escapes accordingly.

Another factor, of course, is cost. Nitrogen-equipped service centers will fill up your tires with nitrogen for something like $10 per tire, which is a far cry from the couple of quarters (if even that) it takes to trigger the air machine at your local gas station. “When it comes down to a dollar decision, it’s hard to argue that spending as much as $40 for nitrogen in a set of tires is a good fiscal move,” writes Jackson.

“Save your money and just keep an eye on your tire pressures,” he concludes.

Dear EarthTalk: Backyard fire pits have become the latest must-have gardening feature. How bad are they on the environment? -- Michael O’Laughlin, Tigard, OR

With Fall setting in and the mercury starting to drop, many of us want to extend our time outdoors, and sitting around a backyard fire pit has become one of the most popular means to do so. But even though it may be fun—s’mores anyone?—it is not good for the environment, especially during times when air quality is already poor.

It’s hard to assess the larger impact of backyard fire pits on local or regional air quality, but no one questions the fact that breathing in wood smoke can be irritating if not downright harmful. According to the U.S. Environmental Protection Agency (EPA), so-called fine particles (also called particulate matter) are the most dangerous components of wood smoke from a health perspective, as they “can get into your eyes and respiratory system, where they can cause health problems such as burning eyes, runny nose and illnesses such as bronchitis.”

Fine particles also aggravate chronic heart and lung diseases, and have been linked to premature deaths in those already suffering from such afflictions. As such, the EPA advises that anyone with congestive heart failure, angina, chronic obstructive pulmonary disease, emphysema or asthma should steer clear of wood smoke in general. Children’s exposure to wood smoke should also be limited, as their respiratory systems are still developing and they breathe more air (and air pollution) per pound of body weight than adults.

Geography and topography play a role in how harmful wood smoke can be on a community-wide level. People living in deep, steep-walled valleys where air tends to stagnate should be careful not to light backyard fires during smog alerts or other times when air quality is already poor. Lingering smoke can be an issue even in wide-open areas, especially in winter when temperature inversions limit the flow of air.

The Washington State Department of Ecology reports that about 10 percent of the wintertime air pollution statewide can be attributed to fine particles from wood smoke coming out of wood burning stoves. While a wood stove may be a necessary evil as a source of interior heat, there is no excuse for lighting up a backyard fire pit during times when you could be creating health issues for your neighbors.

Another potential risk to using a backyard fire pit is sparking a forest fire. Some communities that are surrounded by forestland voluntarily institute seasonal burn bans so that residents won’t inadvertently start a forest fire while they are out enjoying their backyard fire pits. If you live in one of these areas, you probably already know it and would be well advised to follow the rules.

If you must light that backyard fire pit, take some precautions to limit your friends’ and family’s exposure to wood smoke. The Maine Bureau of Air Quality recommends using only seasoned firewood and burning it in a way that promotes complete combustion—small, hot fires are better than large smoldering ones—to minimize the amount of harmful smoke. The moral of the story: If you need to burn, burn responsibly.

GOT AN ENVIRONMENTAL QUESTION? Send it to: EarthTalk, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881 or e-mail: earthtalk@emagazine.com. Read past columns at: www.emagazine.com/earthtalk/archives.php