Visual recognising the Air Quality Index - a case applied to Hanoi

Posted on February 8th 2015
Share: aqicn.org/faq/2015-02-08/visual-recognising-the-air-quality-index-a-case-applied-to-hanoi

Earlier this week (of February 2015), we got several inquries from Hanoi citizen wondering about the Air Quality Index which was displayed on the Hanoi page (city/vietnam/hanoi).

The main reason for the inquiry was that the Air Quality Index displayed on the World Air Quality Index project was around 50 (green AQI) level, while the outdoor visibilty in Hanoi looked like this:


For reference, on the same day in Beijing where the Air Quality Index in Beijing was arround 180 level, the visibility looks like this picture:



One interresting comment on the above picture for Beijing is that the right-part of the picture is having a worst visibility than the left part. This is actually completely normal, pollution is not always uniform, and depending on the wind direction, one part of the city can have relatively good air quality while the other part can be much worse.

oOo

When comparing the visibility for Hanoi and Beijing (see pictures on the right for a comparitive zoomed view), there is no doubt that Air Quality for both cities is at similar level, and, for sure, than if the Beijing AQI is about 180, then it is very likely than Hanoi AQI is much higher than 50.

However, please note that, sometimes, the poor visibility is due to high humidity rather than air pollution (smog). The easiest way to differenciate between humidity and smog is by checking the haze color. If it is yellow or grey, then very likely this is due to smog. But if it is a clean white, then most likely what you are seeing is water vapor (i.e. humidity).

In case you still have some doubts, you can also refer to the Air Quality forecast for your region: The forecast always starts with the current day, so you can check from the first frames of the forecast animation the AQI level for your city.

oOo

When you notice such issue with reported Air Quality - then, please, drop us an email and we will do the necessary to check, verify the data, and contact the relevant local EPA to get the issue fixed.

The problem with Hanoi actually happened to be an issue with the monitoring station itself emitting too low values. Once the problem was well identified and acknowledged, it took no time for the local Hanoi EPA (Environment Protection Agency) to fix the issue and get the monitoring station working normally again. Many thanks again to the Hanoi EPA for the effort and quick action.


Click here to see all the FAQ entries
  • Nitrogen Dioxyde (NO2) in our atmosphere
  • Ozone AQI Scale update
  • Kriging Interpolation




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    Sobre a medição da aualidade do ar e poluição

    Sobre os níveis de qualidade do ar

    -Valores do índice de qualidade do ar (IQA).Níveis de preocupação com a saúde
    0 - 50Boa0-50: Boa - A qualidade do ar é considerada satisfatória, a poluição do ar representa pouco ou nenhum risco
    51 -100ModeradoA Qualidade do ar é aceitável; no entanto, para alguns poluentes pode haver uma preocupação de saúde moderada para um número muito pequeno de pessoas que são especialmente sensíveis à poluição atmosférica.
    101-150Insalubre para grupos sensíveisMembros de grupos sensíveis podem experimentar efeitos na a saúde. O público em geral não é susceptível de ser afetado.
    151-200Insalubre150-200: Insalubre - Todo mundo pode começar a sentir os efeitos na saúde; membros de grupos sensíveis podem apresentar efeitos mais sérios de saúde.
    201-300Muito InsalubreAdvertências relativas à saúde das condições de emergência. Toda a população tende a ser afetada.
    300+Perigoso300+: Perigoso - alerta de saúde: todos podem experimentar efeitos mais graves para a saúde

    Para saber mais sobre Qualidade do Ar e Poluição, verifique o wikipedia Qualidade do Ar tópico ou o guia AIRNow a Qualidade do Ar e sua saúde.

    Para conselhos úteis de saúde do dr. Richard Saint Cyr, de Pequim, confira o blog www.myhealthbeijing.com .


    Usage Notice: All the Air Quality data are unvalidated at the time of publication, and due to quality assurance these data may be amended, without notice, at any time. The World Air Quality Index project has exercised all reasonable skill and care in compiling the contents of this information and under no circumstances will the World Air Quality Index project team or its agents be liable in contract, tort or otherwise for any loss, injury or damage arising directly or indirectly from the supply of this data.



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