Chengdu Air Quality Worse Than Beijing in June

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  • #41180
    Avatar photoStevec
    Participant

    Last month (June 2014), I recorded the Air Quality Index (AQI) scores for Chengdu and Beijing, once per day for 22 days. During that period, Chengdu air was more polluted than Beijing’s! (SEE SUMMARY BELOW).  The AQI score is considered to be a good measure of air pollution, and the important thing to know is that LOWER SCORE = CLEANER AIR.  Here are June’s AQI results (summary)!

    CHENGDU VS BEIJING June 2014 Air Quality Index (AQI) Scores Summary   –  (scores from aqicn.org):
    –>AVERAGE DAILY AQI SCORE FOR 22 days: Chengdu 141 Beijing 119
    (LOWER SCORE = CLEANER AIR)

    AQI Score (all 22 days combined):  Chengdu 3101 Beijing 2612
    (LOWER SCORE = CLEANER AIR)
    # of Hazardous days: Chengdu 0 Beijing 0
    # of Very Unhealthy days: Chengdu 1 Beijing 1
    —># OF UNHEALTHY DAYS: Chengdu 12 Beijing 6
    # of Unhealthy for Sensitive Groups days: Chengdu 7 Beijing 6
    # of Moderate days: Chengdu 2 Beijing 7
    # of Good days: Chengdu 0 Beijing 1

    LIMITATIONS OF THESE RESULTS:
    1) This is just a data snapshot. I recorded the AQI scores once a day for one point in time (often 2pm), but in reality air pollution levels (and AQI scores) change throughout the day. The AQI scores are updated hourly on aqicn.org. Unfortunately, the average AQI score based on the entire 24 hour period in a day is not available.
    2) For month 1 (June) I only recorded 22 days out of 30. For month 2 (July) I will try to include every day of the month. Stay tuned for July’s results!

    FYI I obtained the AQI scores from the website aqicn.org, which is a foreign (non-Chinese) operated site. (I am not affiliated with the website, but am glad it’s there!).  The people who created the website have installed air pollution monitoring devices in cities across China and use the data derived from them to calculate the AQI scores.  As mentioned above, the AQI score is considered to be a good measure of air pollution, and the important thing to know is that LOWER SCORE = CLEANER AIR.  Feel free to check out the site to read more about it.

    -Steve

    #41182
    Avatar photoAl the Dead
    Participant

    Such data is about as worthless as it gets, since there is no info about what exactly is being measured. Doesn’t make Chengdu any safer or cleaner though.

    P.S. And yeah, i went on site. As expected Chengdu beats Beijing in everything but PM 2.5 (read: dust).  No surprise here.

    #41190
    Avatar photoCharlie
    Keymaster

    Well, this is depressing. I thought the pollution has markedly improved in Chengdu in recent months. It felt much worse in the spring.

    Such data is about as worthless as it gets, since there is no info about what exactly is being measured. Doesn’t make Chengdu any safer or cleaner though.

    I don’t think this is true – judging the air quality by the appearance of the sky would be worthless. AQI is a legitimate way to simplify and communicate the complexities of air quality to laypeople. It’s factored by collecting ground-level ozone, particulates, sulfur dioxide, carbon monoxide and nitrogen dioxide.

    #41192
    Avatar photoRick in China
    Participant

    Right – one thing to keep in mind though is not all particles are created equal when evaluating how they affect our health.. I guess that is why some sites/apps include %s (when possible) of the various particles/gasses being measured. That being said, as a pretty general indicator, I think AQI has been sort of established internationally as a pretty standard measurement that can indicate health affects, so should stick with it as the baseline. I don’t understand how that could be considered “worthless”…

    #41197
    Avatar photoStevec
    Participant

    Hi Al the Dead,

    Thanks for contributing. Yes, the AQI scores above reflect the amount of PM2.5 particles in the air (particles which are 2.5 micrometers are less). Why do you say the PM2.5 particles in Chengdu are merely dust?

    From what I have read, PM2.5 particles are actually considered to be worse for your health than larger PM10 particles,  because the smaller (PM2.5) particles are composed of more toxic things and travel more deeply into the lungs.
    From AirInfoNow.org:

    “Both PM10 (big) and PM2.5 (small) particles can cause health problems; specifically respiratory health (that’s the lungs and the airway). Because the PM2.5 travels deeper into the lungs AND because the PM2.5 is made up of things that are more toxic (like heavy metals and cancer causing organic compounds), PM2.5 can have worse health effects than the bigger PM10.” 

    I agree that it would be nice to see specifics about what the PM2.5 particles (and PM10 particles) are comprised of,  but both PM2.5 and PM10 are often used internationally for  measuring air pollution, so I wouldn’t call the measurements worthless.

    #41209
    Avatar photoniklas
    Participant

    I don’t think this is true – judging the air quality by the appearance of the sky would be worthless. AQI is a legitimate way to simplify and communicate the complexities of air quality to laypeople. It’s factored by collecting ground-level ozone, particulates, sulfur dioxide, carbon monoxide and nitrogen dioxide.

    There’s just so many variables that can make the AQI value diff such as which part of the city a sensor is located in, how high above ground it’s located, if there are big roads or construction nearby etc.

    Maybe they’ve thought about this when installing the sensors so that all sensors are doing the measurement under similar conditions. Anyone know?

    #41211
    Avatar photoCharlie
    Keymaster

    There’s just so many variables that can make the AQI value diff such as which part of the city a sensor is located in, how high above ground it’s located, if there are big roads or construction nearby etc. Maybe they’ve thought about this when installing the sensors so that all sensors are doing the measurement under similar conditions. Anyone know?

    That’s true but you have that problem wherever you take measurements or in whatever way you present data. The US Consulate reports AQI from a single location but the local Chengdu government has 8 testing sites within 3rd ring road (which you can see here by clicking on the map icon). You can see how the pollution varies by location depending on proximity to major roads, etc.

    #41213
    Avatar photoniklas
    Participant

    That’s true but you have that problem wherever you take measurements or in whatever way you present data. The US Consulate reports AQI from a single location but the local Chengdu government has 8 testing sites within 3rd ring road (which you can see here by clicking on the map icon). You can see how the pollution varies by location depending on proximity to major roads, etc.

    Wonder if either of those stations’ values could make a significant drop if the sensor was to be moved to a higher or lower floor. I’m not sure, maybe it wouldn’t differ that much. Seems like more stations have popped up in recent months. Would love to have my own sensor to experiment with to get a better idea of how the values can be affected by different variables.

    #41216
    Avatar photoBrendan
    Moderator

    Would love to have my own sensor to experiment with to get a better idea of how the values can be affected by different variables.

    Surprised no one’s done this yet. Would be a great way to compare results over time if enough accompanying data was collected (weather, cloud cover, visibility level, etc.).

    Here’s the short version though: The air is fucked!!!

    #41220
    Avatar photoCharlie
    Keymaster

    Would love to have my own sensor to experiment with to get a better idea of how the values can be affected by different variables.

    I was researching this a few months ago. Here’s what I found:

    • At the low end for very cheap you can get something like this (which I mentioned in the comments in the Smart Air interview post). It only shows current and average pm2.5 levels (in microns per square meter, which is different from AQI). I have a review of this which I will publish soon, I’ll link to it here. The data that this collects is rudimentary, but works good enough to tell you if your in-home air purifier is working.
    • The next level up is basically something like the Dylos 1100 (or the newer model, the Dylos 1700). This is far more advanced than the Samo Air and also costs ten times as much, but provides much more accurate pm2.5 and pm10 data. The upgraded 1100 or the standard 1700 have PC interface ports so you can collect and automatically chart changes in air quality over time on a graph (this is what Smart Air uses on their Particle Counting blog). You could use this to chart interesting things like see how the air quality changes over the course of the day, when it begins or stops raining, when you open a window, etc.
    • Two students in England made a custom air quality and weather monitoring device called the AirPi and offer it for sale. I tried to get one to install it on my roof and have it provide live data on weather and air quality on CL. I got on the Tindie wait list and never heard anything – then I contacted the creator and pitched the idea of setting on up in Chengdu to gather data and got no response. The project has basically been neglected seeing as the creator is a young adult probably pursuing other things. This would be a really cool thing to have, though.
    #41239
    Avatar photoChris Ziich
    Moderator

    I must have been in China for too long, because I’m very satisfied when the AQI is under 200.

    #41244
    Avatar photoIan
    Participant

    First photo taken 26th June 2014 second photo taken 28th June 2014

     

    #41254
    Avatar photohankrandell
    Participant

    Having lived in Australia, I used to think air quality in HK is poor.  After the last 2 years in China, when I now landed in HK it is really a breath of fresh air.

    #41280
    Avatar photoRick in China
    Participant

    I just came back from Dali, rockin’ 20 AQI. The fresh air and sunshine made mornings, and the whole day, much more energetic… realize just how lethargic poor air and lack of sunshine can make you feel.

    #41281
    Avatar photoCharlie
    Keymaster

    I just came back from Dali, rockin’ 20 AQI. The fresh air and sunshine made mornings, and the whole day, much more energetic… realize just how lethargic poor air and lack of sunshine can make you feel.

    Totally. Dali is a wonderful place with so much natural beauty.

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