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.
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