Outside/In: The Climate and Health Consequences of Burning Woodsmoke
In New England, burning wood in the woodstove can conjure the quintessential image of a cozy winter day - snow falling outside, a pot of tea, tossing another log onto the fire. But the woodstove is not as straightforwardly wholesome as it seems. The process of burning wood releases molecules like carbon monoxide, soot, and fine particulate matter.
To learn more, Outside/In producer Justine Paradis spoke with Jonathan Mingle, a freelance science journalist and writer. He’s reported on the climate and health consequences of wood-burning in Vermont for Inside Climate News in collaboration with the Weather Channel.
This interview has been condensed for clarity and brevity.
Justine Paradis: How common are wood stoves in New England?
Jonathan Mingle: I can speak to Vermont where I live, but the numbers are comparable across New Hampshire and Maine. In Vermont, over a third of households rely on wood for heating to some degree, and Vermonters lead the country in per capita emissions of particulate matter. We've had cold winters up here for a long time in Vermont and New Hampshire, and a lot of trees. So not surprisingly, that led to this widespread practice of burning cordwood and stoves to heat your home. And, culturally there’s this prized sense of self-reliance that a lot of people have -- that old Yankee, I can do it myself tradition of cutting down your own wood and splitting it and throwing it in your wood stove.
Justine: There's also a lot of pride in stacking skills.
Jonathan: Yes, everyone seems to have a strong opinion on the best way to stack your wood and to light your fire, and what’s the best species of wood to make a really warm fire.
Justine: Wood stoves can feel so wholesome, but what's the issue?
Jonathan: People have been burning wood for so long, there's this tendency to assume, oh, what's the problem? It's natural. What could be more natural than wood? But it turns out that wood smoke is just a toxic soup of nasty stuff. And that's true when you burn any carbon based fuel, you get carbon monoxide, which we all know is an odorless, invisible, and potentially lethal gas. You have methane, which is a big contributor to climate change. You have nitrogen dioxide, which is a respiratory irritant, sulfur dioxide, polyaromatic hydrocarbons like benzene, which is a carcinogen, formaldehyde, and volatile organic compounds. And then, of course, last but not least, you have particulate matter, which is the most widely studied and measured kind of air pollutant and the one we use as a proxy for the health impacts of all the other ones... So, when you look at what's actually in woodsmoke, it's pretty alarming.
Justine: I just feel like it hurts to hear this, you know. There's nothing sacred, even something so beautiful as a wood stove or a wood fire. But, you know, what are the health consequences of breathing this in?
Jonathan: I hear you. I have a wood stove and I love splitting wood. I like burning wood as backup heat. But the science is pretty clear on this. Especially if you have kids or someone with asthma in the home. Kids’ lungs are developing, they are lower to the ground where a lot of pollutants pool. They're just more vulnerable than adults to air pollution. And globally it's an even bigger problem -- every year about 3.8 million people die prematurely from breathing in indoor air pollution. That's more than have officially died from covid since the pandemic began. And so it's a pandemic hiding in plain sight. But even here in the U.S. there are people who die because they breathe this stuff in. And indoor air is unregulated. When you start to go down this rabbit hole, the romance of burning wood gets burned off pretty quickly.
Justine: Well, the other element of this is that it's a conservation and a climate issue. Wood is often framed as a renewable fuel source. But that's complicated, right?
Jonathan: It's really complicated. When you ask researchers if burning wood is a good idea to slow down climate change, the answer you get is that it depends. It depends on where that wood is coming from and if it's coming from waste or leftover material from sawmills or paper mills. So if it’s stuff that would have been produced anyway, it can be a net reducer of carbon emissions. But if it's coming from mature trees that are being felled just to meet this increased demand for wood, that's bad for the climate.
Justine: So if someone has a wood stove, what can they do? Do you have any recommendations?
Jonathan: The first thing is to look into getting one of these newer EPA certified stoves, which are required to stay under a tighter emissions limit for particulate matter. If you're not in a position to do that, then make sure you're burning dry wood and make sure you're keeping it hot, because low temperatures and smoldering fires tend to be more polluting. But even if you do all that, there's going to be some emissions. So a lot of people who can afford it choose to just retrofit their house, make it tighter, more energy efficient, and install air source heat pumps. Heat pumps are increasingly popular and available, and installers are more familiar with them now, to the extent that Maine has a target of having 100,000 heat pumps installed in homes by 2025. There's no emissions coming out of the heat pump into your home. But for people who still want to burn wood, and I'm one of them, I have heat pumps in my house for heating, but I also have a wood stove for backup. I just use it sparingly and try to use it with dry fuel.
Justine: And that really does make a difference.
Jonathan: It does make a difference. And if you're not sure how to do it, just go knock on your neighbor's door and I'm sure you'll find people willing to tutor you. Or there’s YouTube.