Is Wood Good?

A FB friend of mine shared an article with me that was recently published in The Guardian. Like my family, he supplements his heat with wood during the colder months at our latitude. My sense is that he was more concerned and inquisitive than alarmed. His friends on the email chain appeared more alarmed. The background is as follows:

A recent study conducted in Athens, Greece has resulted in research that supports the notion that wood burning stoves in urban areas are responsible for almost half of people’s exposure to cancer-causing chemicals found in air pollution particles.  I am reminded that only two generations ago my forebears heated their homes with coal.  Yup, bituminous coal for daytime heat and anthracite for banking the fire overnight.  The last house I owned still had the coal chute built into the basement wall for easy delivery.  And the rafters above the footprint of the coal bunker were still covered in coal dust.  The air quality back then was horrific.  Burning all that coal left a pall - a miasma - across the sky when conditions were sub-optimal. PAHs ruled.

The introduction of gas forced-air heat technology made the previous technology obsolete by the time the 1960s rolled-around.  Like coal, natural gas was a non-renewable fossil fuel; but cleaner-burning than its predecessor. But I digress.

The polycyclic aromatic hydrocarbons (PAHs) in tiny pollution particles are produced by burning fuels and have long been known to have carcinogenic effects. This new study examined the sources of the PAHs and suggests that wood burning produced them in larger quantities than the diesel fuel or gasoline used for vehicles.

This is important on several levels. Researchers suggest that smoke from wood burning is much more toxic than other types of particles suggesting that wood burning is a significant driver of long-term carcinogenic risk. Nevertheless, the concentration of the PAHs in the Athens study was below EU limits but double the World Health Organization’s reference level. Based on WHO data, the PAHs in Athens would be expected to cause 5 extra cancer cases for every 100,000 people.  Can the EU and WHO have it both ways?

The questions that come to mind include the following:

• One study, in one city.

• Urban communities are crowded. More dwellings means more wood stoves concentrated in a smaller area. What about rural dwellings?

• The study suggests that the complex topography of the basin favors the appearance of mesoscale flows throughout the year and the frequent stagnation of air masses. There are seasonal non-local contributions from the Black Sea area, Balkans and Eastern Europe. There are similar effects found in Los Angeles and Denver.  Heck, in Ireland peat continues to be burned as biomass for generating electricity.

• Of critical importance to this blogger are the type of stoves used. Are they ordinary fireplaces or something more efficient? Are they regulated and thus engineered as to reduce emissions output? We have a wood stove that is EPA certified. It operates at an exceedingly high temperature, uses only outside air for the combustion of wood and wood gases. At operational temperature there is more heat produced, more complete combustion and less smoke. Most stack emissions are water vapor. There is also less ash produced.

• We burn only dry, aged hardwood. The study suggests that Athenians burn fresh softwood (pine) and hardwood (olive, oak, beech) This practice has been consistent for residential heating over recent years.

My conclusion is that this study is incomplete and raises more questions than it answers. I would like more background and further study of rural v. urban air quality, results with various wood fuels and stove technology and regulation. If I had to hazard a guess, US and Canadian air quality standards are stronger with added emphasis paid on cleaner-burning technologies in North America. That our diesel regulations are stricter than those of Europe comes to mind. 

Wood is also a sustainable fuel resource.  Non-renewable fossil fuels used for direct burning or power generation is unsustainable.

With modern stove technology my take-away is that choosing to heat with wood continues to be good. 

Link to the study is here.