Wondering what the massive, yet brief, spikes in Guangzhou are...the ceiling of the Hazardous category of the AQI is capped at 500. That would mean that readings like the 1/12/13 of 827 are quite literally 'off-the-chart.'

The safe bet would be some atmospheric event that concentrated existing pollution. Any new pollution generation event would be expected to have more impact on the baseline, right?

Did a bit more poking around. Could be a temperature inversion causing a spike (http://www.wrh.noaa.gov/slc/climate/TemperatureInversions.ph...). Would be heavily dependent on the location of the sensor and surrounding topography, which all fits. If I find time, I might overlay weather data and see what it looks like.

Possibly. They appear to be events that truly saturate the sensor, as all of the spikes have the exact same concentration and air quality index readings (995 and 827 respectively).

this is really cool!

it'd be even cooler if you could use data for some large, densely populated US cities as benchmarks, adjusted for time zone differences

I know anecdotally that the air in Chinese cities is bad, but I've never been really sure how much worse it is than say, LA, or NYC

Here's some good data for the Los Angeles area:

http://www.aqmd.gov/smog/Forecast.htm

http://www3.aqmd.gov/webappl/aqdetail/AirQualityParameterDat...

Click on "Historical Data" to create a graph.

Bottom line, LA seems to hover around 25 µg/m³.

I wanna see Xi'an's levels. I've been to Shanghai and Beijing and they are nowhere near as bad as Xi'an.

I'm not sure if there's a historical archive of the official Beijing city readings, but if so I'd love to see those figures interposed with the unofficial Beijing embassy readings.

ah, I would love to see HK's levels..