Fun with Air Pollution Indices (APIs) in Hong Kong and Beijing

Note: This page is woefully inadequate, contains errors in basic data, premises, and analysis, and fails to address any actual issues concerning air pollution in either Hong Kong or Beijing. I hope to address these issues in the relatively near future; in the mean time, it is helpful for me to keep this page as it is.

Links to this page from Wikipedia and other sites lead me to emphasize again (and I cannot emphasize enough) that this should not be used as a source of information about APIs. The basic argument, that Hong Kong and Beijing calculate APIs differently, is true, but pretty much everything beyond that is suspect. Also, I’m probably never going to update this page.

Both Hong Kong and Mainland China report levels of air pollution using a number called an “API”, or “Air Pollution Index”. These numbers are calculated based on levels of specific pollutants, but are not directly equivalent due to different calculation methods. Hong Kong’s API is generally more useful than the mainland’s, as it is calculated based on levels of seven different kinds of pollutants (Sulfur Dioxide, Nitrogen Dioxide, Carbon Monoxide, Ozone, Total Suspended Particulates and Respirable Suspended Particulates), as opposed to the mainland’s three (Sulfur Dioxide, Nitrogen Dioxide, Total Suspended Particulates).

Having lived in both Hong Kong and Beijing, I decided to compare the two cities, mostly to see how much worse Beijing’s pollution really is. To simplify matters, I’ve kept the comparison of APIs to the pollutants both indices have in common: Sulfur Dioxide (SO2), Nitrogen Dioxide (NO2), and Total Suspended Particulates (TSPs). All pollution concentrations are in microgrammes per cubic metre.

The raw numbers:

Now the graphs:

Note: This chart is essentially misleading; the only pollution form in which the Air Pollution Indices of each city are directly comparable is TSP (Total Suspended Particulate) pollution. And even then, the numbers aren’t exactly equivalent (see graphs). That said, it’s still fun to note that in terms of TSP pollution, Hong Kong’s “Very High” is Beijing’s “Lightly Polluted”.

Today in Beijing, the API is expected to range from 275-320; that’s pretty gross however you look at it. I suppose it’s good to know that in terms of SO2 and NOx, this isn’t equivalent to a Hong Kong 275-320; it’s probably closer to 175-220. Particulate pollution levels are probably pretty close to a Hong Kong 275-320, which I think means I will contract lung cancer some time in the next two weeks. I could work out the numbers exactly, but I’ve already spent too much time on this and can’t be bothered any more.

I am also annoyed because I thought it would be easiest to export the contents of this page to HTML from a Word document, but the HTML generated was so awful that I had to redo it. Now the source is nice and clean.

Sources:
“Severe Beijing Air Pollution Information Emerges”, [http://www.pnl.gov/china/bjplca.htm]



Hong Kong Environmental Protection Department Website, [http://www.epd.gov.hk/]