Like Tree8Likes
  • 1 Post By GeoTommy
  • 3 Post By shri
  • 1 Post By Plutark
  • 2 Post By jw1701
  • 1 Post By shafiq

AQHI vs AQICN discrepancies

  1. #1

    Join Date
    Jan 2011

    AQHI vs AQICN discrepancies

    Can't see very far outside this morning.

    Seems like a big difference between the Government's data on and the data on

    For example, let's take the numbers for Central/Western at 6am this morning:


    Date Time NO2 O3 SO2 CO PM10 PM2.5
    2019-01-12 06:00 110.0 0.6 12.0 - 79.9 59.9


    AQICN has PM2.5 maxed out in the reds around ~150 while the government's AQHI only has it at 59.9 (with an orange color label on their map) but the gov's AQHI has a higher reading for PM10.

    Whose numbers are correct? Did somebody not calibrate their machines properly?

    (...alternatively just ignore both websites and wear a mask)
    JAherbert likes this.

  2. #2

    Join Date
    Dec 2010
    Wrong side of the door to hell

    I haven't used the government site since they changed to their own formula, producing totally meangingless numbers and colours. I use AQICN now where I can easily see the individual pollutant levels. Plus my own eyes, which tell me it's shit outside.

    As to the difference between the 2, AQICN converts values to US EPA standard, so would need to check what hocus pocus the govt is using.

  3. #3

    Join Date
    Dec 2002
    Plus my own eyes, which tell me it's shit outside.
    Very true today. Horrible visibility while the sun is out is a good indicator that its a mess.
    kimwy66, Morrison and chingleutsch like this.
    Have a GeoExpat related problem - please create a support ticket.

  4. #4

    Join Date
    Apr 2012

    I remember someone saying it was because the government doesn't put weight on PM 2.5. Because you know it's just the worst pollutant because of its tiny particles your nose can't filter out. I believe AQICN over the gov one, for the simple reason that HK gov will use whatever metrics show they're doing a great job fighting pollution.

    The air has been absolutely disgusting so far this year and I can't remember when it was this bad.

    kimwy66 likes this.

  5. #5

    Join Date
    Jun 2011

    It felt like air quality was on a positive trend for 3-4 years now, agree this year it seems to have reversed. Just random that weather is trapping pollutants more or has something changed in China again?

    And yes, HK government again shining in their solutions. Every definition of air quality says its horrendous outside today. WHO standard, Australia, UK, EU, USA. But HK is green or orange.. ..great job guys.

  6. #6

    Join Date
    Apr 2003
    Hong Kong

    yeah, because the air was so obviously poor, I checked and found the same. HK map shows everything is fine, aqicn shows red flags PM2.5 over 180 in yuen long and the western side.

  7. #7

    Join Date
    Nov 2010

    using the Air Matters app and switching between indexes you can see:

    AQI (China) - 86

    AQI (USA) - 173


    Morrison and shri like this.

  8. #8

    Join Date
    Dec 2005

    AQICN uses index and HK govt uses microgram per cubic meter. 59.9 ug/m3 is equal to 152 in aqi index. Values are not directly comparable and aqi gets the air quality reading from the govt temetric network of air quality monitors.

    greenmark likes this.