Shanghaiist recently ran a good piece explaining the basics of air pollution, which is a great segue into my occasional series of posts about Shanghai Air Quality. People are freaking out about the Air Quality again, which happens periodically.
In early 2011 I gathered some data about Shanghai’s air quality, did some simple math, and made a few graphs, wondering if the Shanghai World Expo had been a period of better air quality. Now that we’re a healthy term into 2012, I thought it was a good time to evaluate 2011 for air quality, and perhaps play with a few more graphs to see if we can make sense of Shanghai’s Air Quality in 2011 juxtaposed against the previous 10 years.
For review, Shanghai measures PM10, SO2 and NO2. Data previous to this set measured API in aggregate and always noted “Total Suspended Particulates” as the chief pollutant. So, that’s useless and thus excluded.
Also note that these numbers are not raw (otherwise they’d be in Parts Per Million), they are integers derived by the API formula, explained here. I suppose I could have done the math backwards ad derived the core values, but there are PhD candidates on top of that.
I make no claims of any sort about the accuracy of the source data, which was gathered from the Shanghai Environmental Education Center. The site and the ministry do not go into detail about their methods, testing sites, or any other pertinent details, which ruins the fun.
Here’s the big graph, PM10 for the last 11 years.
Click through to see the SO2 and NO2 graphs, and a much much more! (also click any graph to biggify)
The above graphs are a lot of data, but the 200pt trend line helps detect differences from year to year — and there aren’t many. It is hard to see in this scale, so let’s look at a different scale!
Year on Year graphs (2011 in WHITE)
Ooh, look at those 500 days. There were 2 500 API days in 2011, May 2nd and 3rd, 1 in 2011, and 1 in 2007. None before then. Beyond that spike, the White line seems to have at least one color above it most of the way through.
This looks pretty promising for a lower SO2 year than years past.
the NO2 data from 2000 is an outlier, I believe they were measuring NOx and not noting it correctly. Not as convincing as the SO2 charts, but 2011 looks like a pretty decent year, right? I’ve done some sleuthing and data analysis to create some graphs worth reading. Tune in Friday for those!