LETTER: AIR POLLUTION FROM WOOD-STOVES
It has long been well known that fine particulates and volatile organic compounds (VOC’s) containing carcinogens, including benzene and other toxic chemicals, are released from wood burning stoves and that these are a proven serious health hazard.
However, what is not widely known is the scale or magnitude of the impact of wood burning stoves on particulate levels in the atmosphere, especially in urban areas.
EPA Certified wood stoves have a limit of 4.5 grams per hour of particulates, recently reduced from 7.5 grams per hour for non-catalytic stoves. To a majority of people these numbers by themselves are meaningless. So what can these be compared with to put them in perspective?
Researchers at Kings College in London (UK) have used techniques which can identify and measure the particulates from wood burning separately from particulates resulting from vehicles traffic. In some cities, they have seen significant spikes in the evening when folks get home from work and fire up their wood stoves and have measured levels that are comparable with particulates from traffic.
One newspaper article publicising this research has the headline ”Wood burning stoves in pollution shock” and starts by saying “Trendy ‘eco-burners’ supposed to cut greenhouse gas emissions – but are as bad as an old diesel engine, say scientists.”
Another article in the reputable BMJ (British Medical Journal) has the headline “Another misguided policy – wood stoves: as many PM2.5 (fine particulates less than 2.5 microns) as roads, and increased global warming.” It goes on to say “emissions from domestic wood stoves in the UK accounted for 17% of the fine particulate emissions, only marginally less than the 18% from all road transport”. It also says… “a log burning stove emits more PM2.5 (fine particulates) than 1000 petrol (gasoline) cars with estimated annual health costs of thousands of pounds per stove per year .”
Equating pollution from wood stoves with levels of pollution from vehicle traffic is intriguing as it represents something that people can relate to.
Information is available in various U.S. Environmental Protection Agency (EPA) reports which gives the quantity of fine particulates and the levels of VOCs emitted from wood stoves and other wood burning appliances. Similar information is also available for pollutants emitted from vehicle engines whilst idling, so it is possible to create a relationship for comparison.
Using numbers from these reports it would appear that the emissions from an EPA certified wood stove are equal to the amounts emitted from about 4 to 6 full-size diesel pickup trucks, idling continuously, over the same operating period. It is far worse for a non EPA certified wood stove or appliance. The worst offenders can emit the same amount of pollutants as up to 35 idling full-size diesel pickup trucks depending on the type of appliance and how it is operated.
These shocking numbers indicate that anti-idling campaigns or bylaws relating to vehicle idling and air quality, (which make it an offence to idle a vehicle for more than a few minutes,) are insignificant and are only dealing with the tip of the iceberg when compared with the pollutants arising from wood burning stoves.
If municipalities are genuinely concerned about air quality and committed to meeting carbon neutral targets, then perhaps it is time to consider taking action on the use of wood stoves within municipal limits.
Asthmatic sufferers, people with other respiratory problems and those with small children would surely thank Councils for taking some action to reduce or eliminate this source of winter air pollution.