Cold winter air laden with smoke particles is no joke - it's a health issue for us all, but especially for Canterbury, Nelson, and Otago residents, where winter air pollution is worse than in other places.

On 1 September 2005, the Ministry for the Environment tightened the emission rules for new woodburners for all urban areas.

Before, the smoke had to consist of no more than four grams of particulate (smoke particles) per kilogram of dry wood burnt. Under the new rules, the limit for woodburners installed after 1 September 2005 is only 1.5g, and the burners must be at least 65 percent efficient.

Because of their pollution problems, in Canterbury and Nelson the authorities have gone further. Canterbury has lower emission-limits than what the National Environmental Standard (NES) requires and they both carry out physical checks on woodburners, to make sure production-line models' critical dimensions are the same as those of "sample" models submitted for testing. (See "Compliance testing" below.)

One upshot of this is that the Canterbury and Nelson local authorities discovered that some woodburner models in stores had design changes and weren't the same as the sample that had been submitted to the lab for testing.

And, as we reported in our 2007 news item, the Ministry for the Environment also did some checking. This led to a number of models being removed from the ministry's online list of authorised woodburners (which is limited to models that meet the Canterbury and Nelson requirements). It also prompted the ministry to investigate further.

Not good enough!

In its 2008 investigations, the ministry randomly selected 10 woodburners and bought them anonymously. It then checked their efficiency and emissions, and whether they were true to their design.

The results were disturbing. Of the 10 burners, only 2 passed all the tests. Of the remaining eight, one was borderline in its efficiency and seven failed. Two failed because of a minor problem, three because of a moderate problem. One had a serious problem, and another a very serious problem.

These are major shortcomings. Some woodburner manufacturers should be blushing.

What's more, it's probable that non-compliant woodburners have been installed in urban homes since 2005.

Check your local air quality

Regional councils monitor air quality every day and most put the data on their websites. The following cities and towns have monitoring data live on their regional council website:

Tauranga, Rotorua, Whakatane, Te Kuiti, Tokoroa, Taupo, Hamilton, Putaruru, Reefton, Rangiora, Kaiapoi, Christchurch, Ashburton, Timaru, Waimate, Geraldine, Alexandra, Clyde, Cromwell, Arrowtown, Ranfurly, Central Dunedin, Mosgiel, Milton, Invercargill, and Gore.

Compliance testing

All new woodburners must be tested for compliance with the National Environmental Standards (NES) - and this must be done by an approved laboratory. The manufacturer sends a sample model to the lab, which notes the critical dimensions of the model and tests its burner's efficiency and emissions.

If a model passes the tests, it's NES compliant. The manufacturer then labels all production of that model as such.