Courtesy of The Firewood Association of Australia
In the US the federal EPA has recently released a proposal to update the 1988 emission limits for new wood stoves. While the new legislation is still in its consultation stage, it is proposed that it will be introduced as law in 2015 and will have a 5 year phase in period.
In the US they measure particulate emissions in grams per hour instead of the grams per kilogram that we use in Australia, which makes a direct comparison difficult. But the intent of the legislation is much the same as proposed in the recent draft of the Australian wood heater emission standards, which is to significantly lower emission rates for new heaters. [The Alliance did a more in-depth analysis of the new, proposed Australian wood heater regulations in August 2013. - eds]
Similar to the situation in Australia, it appears that these new limits are generally supported by the large heater manufacturers, who have the capacity to develop new, compliant models, but opposed by the smaller manufacturers who cannot easily afford the costs of development and testing.
In both the US and Australia the new limits will not apply to existing heaters, so any lowering of neighbourhood smoke levels will take a long time to materialise, given the 20 year plus lifespan of most wood heaters. In both countries wood heater manufacturers would like to see governments support (or enforce) the replacement of old heaters with new models, for the obvious reason. However, it appears that governments are reluctant to head down that path.
Because these new designs of wood heater are much easier to operate without creating excessive smoke, the gradual replacement of installed heaters should result in less smoky heater complaints. The experiment carried out in the town of Libby, Montana where every wood heater in this small town was modernised or replaced, showed that improving the heater stock can have a modest impact on smoke levels (30%). However, this experiment clearly shows that heater operation practice has by far the greatest influence on smoke emissions and is something that can by changed at no great cost with immediate impact.