In 2007 the Health and Air Pollution in New Zealand report (HAPiNZ) from the Ministry for the Environment estimated that fine particles (PM10) in the air in New Zealand caused 1,170 premature deaths each year.
This estimate was based on an epidemiological study from Europe and assumed that PM10 from all sources - blast furnaces, diesel trucks, petrochemical industries, or from your toaster - are all equally toxic. Most PM10 in the New Zealand air has been fairly reliably measured as coming from home fires.
During the past 20 years the concentration of PM10 in, Christchurch air has about halved. There is no doubt about this. The scientists who measure the concentration in Christchurch are very good scientists.
Acting on the advice of the 30 or so air quality scientists advising the Ministry for the Environment writing in the Health and Air Pollution in New Zealand (HAPiNZ) reports, Wilton and Familton, who work for the Canterbury Regional Council (ECan), concluded that because the toxic PM10 had gone down so much - there were only 150 admissions to hospital for respiratory disease in 2011 compared with 260 in 2001 and only 190 deaths from respiratory disease in 2011 compared with 320 in 2001 - these huge benefits were the result of ECan policies to reduce PM10 from home fires and log burners.
Sounds great, doesn't it?
But hang on. These zealous scientists working for ECan and Ministry for the Environment did not count the actual numbers of the sick and the dead. They only estimated the number, using a formula from the HAPiNZ reports.
The Ministry of Health statistics from the Canterbury District Health Board show a different story. They show that the actual number of sick and dead in Christchurch had not gone down as ECan had claimed .In fact, the number had not decreased - it had gone up!
There were not a hundred fewer deaths as they had claimed, but around 100 more.
There were not 100 fewer hospital admissions as they had claimed, but around 1500 more.
You can decide which to believe.
Whatever the facts may show about the toxicity of PM10, they clearly show that reducing concentrations of PM10 in Christchurch by putting out home fires and log burners has not resulted in improvements in respiratory health.
This experiment has cost Christchurch people hundreds of millions of dollars.
ECan is dead set on repeating it in Timaru.
Pat Palmer is a foundation member of Association for Independent Research who has been studying the relationship between air pollution in Christchurch and claimed health effects since 1996.