September 28, 2011

Auckland air as dirty as New York?(updated 2x)

The Herald is reporting a WHO report that says the average levels of particulate air pollution are higher in Auckland than in New York.   The Environment Minister doesn’t believe it, and I tend to agree with him.

As the Green Party correctly points out, Auckland has far too many cars on the road.  But the same is true of New York, even though a larger fraction of their cars are taxis.  Auckland is surrounded by ocean, and the background levels of pollution in incoming air are very low.  New York is surrounded by a conurbation with a population of 21 million, nearly all of whom drive everywhere, and gets a substantial amount of pollution from the old coal-fired powerplants in the Ohio Valley.   Yes, the Northwestern Motorway is full of cars, but have you seen the Jersey Turnpike?

As usual, the newspaper doesn’t link to the data, but it’s not hard to find. That’s where things start to really get strange.  The map of global PM10 levels shows Auckland, Hamilton, Wellington, and Christchurch as yellow dots, having levels over 20μg/m3, and a green dot for what is presumably supposed to be Dunedin (the dot is roughly on Mt Cook).  That matches the stories.  If you download the Excel database and scroll to New Zealand, you see

That is, the WHO database agrees with the Environment Minister, not with the WHO map.  There are some other minor anomalies — for example, nearly all other countries have cities listed in increasing order of air pollution, but NZ doesn’t.   It’s also worth noting that the database gives the NZ Minstry of Environment as the source of the data.

Update:  Adam Bennett, the reporter who wrote the Herald story, says that the WHO have changed the data since they went up and sent me a copy of the original.  That explains some of the discrepancies, though the WHO certainly should have noted the change (they have a nice Read Me sheet in the spreadsheet that would have been perfect for the purpose).  The figure for Dunedin looks strange, but it turns out that Dunedin consistently has moderate levels of PM10 pollution, rather than having low background with seasonal peaks.

Updated again: On Radio NZ Morning Report, WHO confirms that they made a mistake in compiling the database and that they have corrected the numbers. The map has also been fixed (apart from the location of Dunedin).

 

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar

    So just to clarify, Auckland’s data *was* incorrect in the report from WHO and it is not as polluted at NYC? If so, then the Herald needs to update their story quickly to reflect it.

    13 years ago

  • avatar
    Thomas Lumley

    Yes, that’s right. All the NZ data was incorrect, and Auckland is not remotely as polluted as NYC or Tokyo.

    The Herald should be updating their story — they certainly know about the changes.

    13 years ago

  • avatar

    The problem is that there’s literally hundreds of stories now about the incorrect figures when you search in Google news, I doubt there will be the same number written about the data entry mistake.

    13 years ago

    • avatar
      Julie Middleton

      … and that’s the worry. People will have “Auckland’s air is bad” as the take-home message – worrying when tourism is our single largest foreign exchange earner. However, it will be easier to get the correct message out there if the Government decides to kick up a fuss and asks for a formal apology from WHO, which will make the news in the way a straight correction wouldn’t. Environment Minister Nick Smith was sufficiently concerned to have a press release out on Tuesday expressing doubt about the figures before we knew that “human error” at WHO was the problem.

      13 years ago

  • avatar
    Thomas Lumley

    The correction articles are starting to appear. There seem to be quite a lot of them, partly because people want stories about NZ being clean and partly because it was someone else’s mistake, not a media mistake.

    13 years ago

    • avatar
      Julie Middleton

      What do you think are the implications for WHO of having made such an error? Apart from getting a dent to its credibility ….

      13 years ago

      • avatar
        Thomas Lumley

        I think the main issue is that both the original stories and the ‘WHO got it wrong’ stories distract from the WHO’s main point. The point isn’t that Auckland is above or below a pretty strict PM10 threshold. The point is places like Lagos and Kathmandu, Delhi and Qom, with annual average levels higher than ChCh’s worst days.

        Industrial (though not agricultural) pollution has been decreasing in the Western world for more than 50 years. London doesn’t have the lethal pea-soup fogs it had when my mother was a medical student. The Cuyahoga river, which caught fire in 1969, now supports bald eagles and blue herons. Lead pollution in the US air has fallen so far that there was serious debate a few years ago about just declaring victory and stopping monitoring.

        On the other hand, in many developing countries pollution is increasing rapidly.

        13 years ago

  • avatar

    One doesn’t have too look too hard to find the origin of the error in this data. The initial figures reported – if listed in the WHO order – are:
    D: 19, C:20, W:21, H:22, A 23.

    Anyone see a pattern? A consequence of a spreadsheet auto complete function perhaps?

    It is worth also noting that the ‘corrected’ figures from the WHO on the 29th Sep (screenshot in the post) still did not match the the Ministry for the Environment 2010 data (D:25, C:17, W:11, H:13, A:15)

    The WHO spread sheet has been updated *again* and now the correct data is included.

    But Dunedin is still spelled ‘Dundedin’….

    13 years ago

    • avatar
      Thomas Lumley

      Since neither the name of the city nor the location on the map match Dunedin, why are we assuming that’s what they meant? Perhaps they think there is a city called Dundedin somewhere near the Franz Josef glacier.

      13 years ago