Wood Heat: Up In Smoke?

[Paul J Hetzler]

Where There’s Smoke

An upswing in woodstove use might sound yawn-worthy, but recent findings about the dire health effects of wood smoke might mean the long-term future of wood as a heating fuel is in question.

As someone who grew up with wood heat, I assumed  it was hands-down one of the most sustainable, eco-positive fuels for home heating. Like many other widely shared conventions, it turns out the veracity of that assumption depends on a lot of things.

How many people burn wood in a given locale is an obvious factor. The number of homes using wood heat rose sharply in the years following the 1998 ice storm which left residents without power for weeks on end. Also no surprise, the COVID-19 pandemic has accelerated the use of wood heat.

My neighbor, who is a longtime chimney sweep, told me he’s noted an increase in the use of wood heat in the past eighteen months. The much-publicized exodus of urban dwellers to the country has meant additional work for him, and he said “I don’t need any more business right now.”

This frenzy of wood burning is ill-timed, however. As reported in The Guardian on 1 January 2021, health-care professionals now say wood smoke “…may be damaging every organ in the body, with effects including heart and lung disease, diabetes, dementia, reduced intelligence and increased depression. Children and the unborn may suffer the most.”

The referenced article notes that “Dr. Nick Hopkinson, medical director at Asthma UK and British Lung Foundation, said both indoor and outdoor pollution caused by wood burning stoves caused serious health issues, from breathing problems to an increased risk of heart attacks, strokes and lung cancer.” The story also states that “…wood-burners triple the level of harmful particulates inside the home as well as creating dangerous levels of pollution in the surrounding neighbourhood.”

The fact is that these fine particulates, smoke elements less than 2.5 microns in diameter that remain suspended in air almost indefinitely, are the real concern. They are tiny enough to lodge in the alveoli, the deep lung tissue, and accumulate there. This can reduce lung function permanently in adults, and arrest the full development of children’s lungs. Other harmful pollutants in smoke include volatile aromatic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs), both of which are known carcinogens.

Again, having grown up around wood smoke and being mostly not dead yet, I could brush off such reports as hyperbole. But I had lived in a remote area with only one neighbor within a mile. Population density matters a lot.

In terms of places where wood-smoke pollution can be significant due to population, let’s look at Montréal. The public health department estimated that on the island of Montréal, wood smoke causes nearly 1,000 premature deaths, over 6,000 childhood bronchitis cases, and at least 40,000 asthma attacks annually. In addition, a city-wide wood-smoke study released in 2000 found that in winter, levels of fine particulates and other dangerous air pollutants were higher in Montréal’s residential neighborhoods than in its urban core. Considering that children are at higher risk of smoke-induced health complications, the grim warnings sound less like exaggerations.

Going back to my friend the chimney sweep, he has a few thoughts on the future of wood burning. Given his profession, he’s not against it, yet he contends “There are greener ways to heat your home than with wood.” First of all, he urges everyone to get a thermal audit of their home. In addition, he’s a big proponent of thermal pumps, which he feels are an underutilized yet readily available technology. He also brought up the issue of forest management, saying that imprudent harvesting is neither sustainable nor “green.”

Today’s catalytic-combustion woodstoves emit little to no smoke when run properly. They also deliver more heat per wood volume burned, so they will save you big on firewood costs. One catch is that burning firewood of less than 20% moisture content is a requisite for the modern breed of stoves to work right. Typically that means at least twelve months of wood being cut, split, stacked and sheltered from rain in a well-ventilated space. I asked my neighbor if he thought the recently arrived ex-urbanites had a decent grasp on woodstove operation. He laughed. “Most haven’t got a clue.”

This is where education comes in. He told me that although cleaning soot and creosote pays the bills, his real passion is educating folks about the importance of burning wood right. Yes, fire is an amazing tool that has been with us since the Stone Age, and back when there were six people on the planet, all that mattered was keeping it lit. Today we have a ton more neighbors, and we just found out that we’ve grossly underestimated the health effects of wood smoke.

It’s imperative to burn clean, burn less, and explore ways to conserve energy and make our homes more efficient. It will keep children healthier, save firefighters from risking their lives at house fires caused by improper wood burning, and save tax dollars. This doesn’t mean entirely giving up on wood-burners – they’re here to stay. As this veteran chimney cleaner told me, “It gives people a sense of empowerment. Plus there’s nothing quite like the warmth from a wood fire.” Amen to that, sir.

Paul Hetzler has been an ISA-Certified Arborist since 1996 and is a former Cornell Cooperative Extension Educator.