Comments on: what is the API and how is it calculated? http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/ Sun, 05 Feb 2012 10:01:22 -0700 http://wordpress.org/?v=2.8 hourly 1 By: Gerry Beauregard http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/comment-page-1/#comment-38936 Gerry Beauregard Wed, 12 Oct 2011 04:04:50 +0000 http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/#comment-38936 For what it's worth... in cases where the PM10 dominates, the Chinese API is equivalent to Singapore's PSI, with exactly the same piece-wise linear function as described here: http://app2.nea.gov.sg/data/cmsresource/20090401682645441976.pdf Sounds like the air pollution is just dreadful in Beijing. Personally I find that once the PSI gets above 50 (into the "Moderate" range, as defined here http://www.nea.gov.sg/psi/), the air is already bad enough that I avoid vigorous outdoor exercise (e.g. trail running), and when it's over 100 (very rare), I avoid going outside entirely. For what it’s worth… in cases where the PM10 dominates, the Chinese API is equivalent to Singapore’s PSI, with exactly the same piece-wise linear function as described here:

http://app2.nea.gov.sg/data/cmsresource/20090401682645441976.pdf

Sounds like the air pollution is just dreadful in Beijing. Personally I find that once the PSI gets above 50 (into the “Moderate” range, as defined here http://www.nea.gov.sg/psi/), the air is already bad enough that I avoid vigorous outdoor exercise (e.g. trail running), and when it’s over 100 (very rare), I avoid going outside entirely.

]]> By: Beijing to Go Coal-Less in 2015 | TheCityFix.com http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/comment-page-1/#comment-18615 Beijing to Go Coal-Less in 2015 | TheCityFix.com Thu, 21 Apr 2011 20:12:25 +0000 http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/#comment-18615 [...] recent string of blue-sky days may be a more common sight to behold in 2015. This past week, the Chinese capital released the [...] [...] recent string of blue-sky days may be a more common sight to behold in 2015. This past week, the Chinese capital released the [...]

]]> By: Vance http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/comment-page-1/#comment-8276 Vance Sun, 16 Jan 2011 01:33:34 +0000 http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/#comment-8276 Louie, It's correct that PM10 vs. API cannot be described by a single linear function. I use piecewise linear interpretation between each point, as graphed here: http://www.livefrombeijing.com/2009/01/why-you-cant-average-apis/. Vance Louie,

It’s correct that PM10 vs. API cannot be described by a single linear function. I use piecewise linear interpretation between each point, as graphed here: http://www.livefrombeijing.com/2009/01/why-you-cant-average-apis/.

Vance

]]> By: Louie http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/comment-page-1/#comment-8238 Louie Sat, 15 Jan 2011 12:56:12 +0000 http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/#comment-8238 Actually, there is a problem with using a single function to convert all API data into mass. If you're in the sub 50 API range, which is where we'd like to be, since you have to be in this range to fall within the WHO annual PM10 standard of 20 ug/m3, the function converts an API of 10 into something like 50, and an API of 50 into 100. It's basically not possible numerically to have an API that falls within the WHO standard. So, maybe your conversion of API = PM10 mass in the 0-50 range is actually appropriate. But, moot point for you poor souls in Beijing anyways, who never see this range anyways... :) Actually, there is a problem with using a single function to convert all API data into mass.

If you’re in the sub 50 API range, which is where we’d like to be, since you have to be in this range to fall within the WHO annual PM10 standard of 20 ug/m3, the function converts an API of 10 into something like 50, and an API of 50 into 100. It’s basically not possible numerically to have an API that falls within the WHO standard.

So, maybe your conversion of API = PM10 mass in the 0-50 range is actually appropriate.

But, moot point for you poor souls in Beijing anyways, who never see this range anyways… :)

]]> By: Louie http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/comment-page-1/#comment-8237 Louie Sat, 15 Jan 2011 12:31:36 +0000 http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/#comment-8237 Vance, The conversion factors you list above are step functions. An API of 200 vs. 201 has a big difference in the calculated mass. On the other hand, if I plot the 6 API points and the corresponding PM mass concentrations, I get a linear function that should let you calculate the mass concentration equivalent of any API. Mass (in ug/m3) = 1.175x + 41.4, where x = given API. This would be a smoother result over the entire API range. Any reason not to use this instead, especially if trying to look at trend data that spans different ranges? Vance,

The conversion factors you list above are step functions. An API of 200 vs. 201 has a big difference in the calculated mass.

On the other hand, if I plot the 6 API points and the corresponding PM mass concentrations, I get a linear function that should let you calculate the mass concentration equivalent of any API. Mass (in ug/m3) = 1.175x + 41.4, where x = given API. This would be a smoother result over the entire API range.

Any reason not to use this instead, especially if trying to look at trend data that spans different ranges?

]]> By: Dunny http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/comment-page-1/#comment-305 Dunny Fri, 25 Sep 2009 04:05:39 +0000 http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/#comment-305 That's interesting that of the 3 pollutants that they measure, 2 are chemical compounds (SO2 and NO2) and PM10 is simply a measure of any particulate 10 microns or smaller? I guess that's why it's typically the dominant pollutant, since it's not tied to a particular compound? I would imagine that the tests for NO2 and SO2 use chemical reactions, where PM10 is just a filter? What is the dominant source of PM10 in beijing? Neat stuff -- sorry to be a year behind on this one... I clicked on "popular posts" shoulda known better. That’s interesting that of the 3 pollutants that they measure, 2 are chemical compounds (SO2 and NO2) and PM10 is simply a measure of any particulate 10 microns or smaller? I guess that’s why it’s typically the dominant pollutant, since it’s not tied to a particular compound? I would imagine that the tests for NO2 and SO2 use chemical reactions, where PM10 is just a filter? What is the dominant source of PM10 in beijing?

Neat stuff — sorry to be a year behind on this one… I clicked on “popular posts”

shoulda known better.

]]> By: Rob http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/comment-page-1/#comment-6 Rob Mon, 04 Aug 2008 05:04:00 +0000 http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/#comment-6 What's the difference between the scale you have listed here, and the new roman numeral scale that, as you have observed, is now posted on the Olympic air quality site?<br/><br/>I guess the roman numeral scale has no particular value? Or do you just expect that it will eventually change sometime before the Olympics? What’s the difference between the scale you have listed here, and the new roman numeral scale that, as you have observed, is now posted on the Olympic air quality site?

I guess the roman numeral scale has no particular value? Or do you just expect that it will eventually change sometime before the Olympics?

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