proof of linear extrapolation of embassy pm2.5-aqi relationship above 500

Well, I’ve officially been called “geeky” on Twitter. I wear the label with pride. Not wanting to let my fans down, I decided to prove my earlier conjecture that the US Embassy linearly extrapolates the AQI-PM2.5 relationship from the EPA’s 400-500 range for concentration values above 500. As I noted before, this is NOT supported by regulatory language in the US, since the PM2.5 concentration almost never goes above 500.

Here’s a plot of the US EPA’s regulatory AQI-PM2.5 relationship definition (blue, stops at 500) as well as a smattering of data from the Embassy monitor (red). Looks pretty clear that the Embassy is just using the EPA’s same AQI-PM2.5 relationship from 400-500 for all values above that.

2 Responses to “proof of linear extrapolation of embassy pm2.5-aqi relationship above 500”

  1. FK says:

    EPA (USA) provides this relation (PM2.5 and AQI) that you tried to plot as above. Latest revision dated 14 Dec 2012 can be found on http://www.epa.gov/pm/2012/decfsstandards.pdf.

    This formulae can also be found on http://en.wikipedia.org/wiki/Air_quality_index

  2. Vance says:

    FK:

    Thanks. I linked to the Dec 2012 revision in my previous post. This post here is showing the relationship >500, which is not defined in the EPA’s regulatory documents. I assumed it would be linear, and these data here prove it.

    Vance

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