WHO double data mix up

This week the World Health Organisation (WHO) released a global survey of urban air quality, but the figures for New Zealand have caused more than a bit of confusion.

The survey collected PM10 values from official sources in over 1000 cities from around the globe. PM10 values are a measure of air pollution, standing for the amount, in micrograms, of particles smaller than 10 micrometers per cubic meter of air (PM10 µg/m³). PM10 particles. The WHO provided the results of their survey in the excel spreadsheet format, available from their air quality website.

You can read the UN WHO press release here.

Initial figures released by WHO were reported in the New Zealand Herald and Fairfax papers as 2009 PM10 figures from the NZ Ministry for the Environment (MfE):

Dundedin 19
Christchurch 20
Wellington 21
Hamilton 22
Auckland 23



New Zealand Herald: Auckland air just as polluted as Tokyo’s
Stuff.co.nz:  Auckland air pollution worst in NZ

Unfortunately for the WHO, this data didn’t actually match with figures from the Ministry for the Environment (MfE) from 2009 – or the more recent 2010 figures – despite WHO referencing the Ministry as the source of the data. The official PM10  figures from the MfE are:

2009 2010
Dunedin 20 25
Christchurch 18 17
Wellington 11 11
Hamilton 14 13
Auckland 16 15


Environment Minister Nick Smith was quick to publically question the WHO data:

TVNZ News: Govt challenges report on New Zealand’s ‘bad’ air
NewsTalk ZB: WHO air quality assessment challenged by Govt
Radio NZ: Air quality claims questioned

By 9.30amWednesday, the data on WHO site had changed again, now listing 2010 figures for NZ cities:

Dunedin 25
Christchurch 11
Wellington 13
Hamilton 13
Auckland 15


The change was picked up by Fairfax reporter Delwyn Dickey

Stuff.co.nz:  UN body backs down on NZ pollution

These values, while a better effort, didn’t fully match up with the MfE figures. The 2010 PM10 figures for Wellington and Christchurch were still wrong.

On 7.45am Thursday a WHO representative fronted up on Radio New Zealand to apologise for the error:

By Thursday morning, the spreadsheet had been changed again and finally the data now matched the MfE website.

Followup coverage:

Waikato times: WHO clears the air over Hamilton (noted the second error)
TVNZ News: WHO apologises over pollution figure gaffe
Otago Daily Times: WHO removes air pollution error from website
New Zealand Herald: NZ air pollution not as bad as report suggested
TV3 News: WHO apologises for wrong Auckland pollution figures

The new figures, while generally an improvement, didn’t play out well for Dunedin (or as the WHO continues to spell it, ‘Dundedin’)…

Otago Daily Times:  Dunedin most polluted city – WHO