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Old 11-24-2009, 05:55 AM
 
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I don't think kramhorse is accurately describing the ALA's methodology. The ALA is ranking Pittsburgh based on Allegheny County, and Allegheny County based on 24-hour Maximum PM2.5 and Annual PM2.5, and they apparently reported a 55.5 three-year (2005-07) average value for the former and 19.8 for the latter. The document kramhorse linked only reports 2007 24-hour Maximum and Annual values, but the only way the ALA could have gotten those numbers is if they only included the highest monitor on the list, Liberty.
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Old 11-24-2009, 11:52 AM
 
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BrianTH: I don’t think anything I’ve said is inaccurate. For the annual standard, you're correct that Liberty monitor provided the values. However, as I mentioned above, even if we go with our next highest monitor value, we'll still be in the top 20 worst metropolitan areas for annual PM pollution (and that's assuming no other metro areas are allowed to remove the monitors they consider "unfair").

Regardless, it's our #1 ranking for short-term particle pollution that creates all the controversy. For the short-term ranking the Liberty monitor provides many of the data points, but by no means does it provide all of them. If you look at the raw monitor data for the Lawrenceville and Liberty monitors between 2006 and 2008 (available from ACHD (http://www.achd.net/air/air.html - broken link)), the recorded 24-hour max at Lawrenceville was higher than Liberty on just under 1/3 of the days. In other words, between 2006 and 2008, I can tell you for certain that nearly a year's worth of data is coming from a monitor other than Liberty. And note that I've only compared Liberty to Lawrenceville, I'm certain there are days between 2006 and 2008 where neither Lawrenceville nor Liberty provided the highest value in the MSA. (e.g., the North Braddock and Harrison monitors record high 24-hour max values with some regularity).


Does the Liberty monitor affect our ranking? Absolutely, but it’s not the only monitor showing a problem, and by no means is it the only local monitor that figures in to the ALA’s short-term ranking. I suspect that most, if not all cities included in the ALA report tend to get a disproportionate number of their data points from one or two monitors located in problem areas, that's just the nature of using a county-wide 24-hour max. In that regard, Pittsburgh was treated just as "unfairly" as every other metropolitan area.



If people (myself included) spent half as much time working on air quality as they spend arguing over the ALA report, we would cease to have an air quality problem.

Last edited by kramhorse; 11-24-2009 at 11:53 AM.. Reason: typos
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Old 11-24-2009, 12:20 PM
 
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Quote:
Originally Posted by kramhorse View Post
BrianTH: I donít think anything Iíve said is inaccurate. For the annual standard, you're correct that Liberty monitor provided the values. However, as I mentioned above, even if we go with our next highest monitor value, we'll still be in the top 20 worst metropolitan areas for annual PM pollution (and that's assuming no other metro areas are allowed to remove the monitors they consider "unfair").
I agree we don't really know how Pittsburgh would rank if they weren't selecting the worst monitor in the worst county in each metro. Which raises the point that the real problem is the data being collected isn't designed to be used for metro-wide rankings, and metro-wide rankings don't really make sense anyway when so much of this is really a localized issue.

Quote:
In other words, between 2006 and 2008, I can tell you for certain that nearly a year's worth of data is coming from a monitor other than Liberty. And note that I've only compared Liberty to Lawrenceville, I'm certain there are days between 2006 and 2008 where neither Lawrenceville nor Liberty provided the highest value in the MSA. (e.g., the North Braddock and Harrison monitors record high 24-hour max values with some regularity).
I don't think that is the ALS methodology--they seem to me to be giving a figure just based on the Liberty monitor again. That said, I again admit I have no idea how Pittsburgh would rank if you applied that methodology in every metro area--but it still doesn't make conceptual sense. I mean, no one is going to have the bad luck to happen to be in the worst place in the metro area every day of the year. So what is this even telling us?

Quote:
In that regard, Pittsburgh was treated just as "unfairly" as every other metropolitan area.
Maybe, maybe not--the basic point is that the rankings aren't really based on a reliable methodology, and so we're just guessing what would happen if you used a better methodology. And again it wouldn't make sense to do that anyway.

Quote:
If people (myself included) spent half as much time working on air quality as they spend arguing over the ALA report, we would cease to have an air quality problem.
My proposed takeaway is that rather than worry about metrowide rankings, we should be focusing on specific local problems and trying to address them. Which happens to be what the data was designed to do in the first place.
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Old 11-24-2009, 12:52 PM
 
24 posts, read 44,579 times
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Quote:
Originally Posted by BrianTH View Post
I don't think that is the ALS methodology--they seem to me to be giving a figure just based on the Liberty monitor again. That said, I again admit I have no idea how Pittsburgh would rank if you applied that methodology in every metro area--but it still doesn't make conceptual sense. I mean, no one is going to have the bad luck to happen to be in the worst place in the metro area every day of the year. So what is this even telling us?
For the short term standard they use data from whatever the highest monitor was for each day:
Quote:
A.S.L. & Associates identified the maximum daily 24-hour AQS PM2.5 concentration for each county in 2005, 2006, and 2007 with monitoring information. Using these results, A.S.L. & Associates prepared a table by county that summarized, for each of the 3 years, the number of days the maximum of the daily PM2.5 concentration was within the ranges identified by the EPA based on the EPA Air Quality Index
(source (http://www.stateoftheair.org/2009/key-findings/methodology.html - broken link))

As I said above, I can tell you for certain roughly 1/3 of those data points did not come from the Liberty monitor.

Quote:
Originally Posted by BrianTH View Post
I mean, no one is going to have the bad luck to happen to be in the worst place in the metro area every day of the year. So what is this even telling us?
That based on a method of inquiry uniformly applied in all major US metropolitan areas, Pittsburgh came out worst for short-term particle pollution. This may not be the most precise ranking method conceivable, but I don’t think anyone would honestly say the results are meaningless. Maybe under a different method we would come out fifth worst, or third worst. Who cares? Let’s address the problems—which a quick glance at Allegheny County air monitor data demonstrates extend beyond just the Liberty monitor/Clairton Coke Works.

Last edited by kramhorse; 11-24-2009 at 12:53 PM.. Reason: typo
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Old 11-24-2009, 01:15 PM
 
Location: Under Mount Doom
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This is only a philosphical point, but important, I think. The desire to dismiss or diminish or debate fine details about how to show the impacts is interesting and strikes me as odd. As for me, I would like to set the bar pretty damn high. It is your health that's at stake, and I would think that more important than your reputation.

Why not get mad as hell and get people to get your city out of the top 20, by any yardstick?! In LA, the smog come from the lifestyles millions of commuters, which are pretty hard to regulate. In Pittsburgh, I would expect the majority of pollution comes from less than 100 point-source polluters. Why not expect more of them, rather than make excuses?
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Old 11-24-2009, 01:31 PM
 
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Quote:
Originally Posted by kramhorse View Post
For the short term standard they use data from whatever the highest monitor was for each day
I don't think the methodology statement you quoted necessitates that conclusion, and again my spot-checking suggests they must have just used the Liberty monitor--otherwise they should have gotten an even higher three-year value. Note they are not just ranking metros, but also grading counties, and I believe what you are quoting is part of their letter-grade process.

Quote:
This may not be the most precise ranking method conceivable, but I don’t think anyone would honestly say the results are meaningless.
Well, I am honestly saying that, or something very close. The data sources in question aren't designed to be used for metrowide rankings, and I don't think they have found a successful way of doing that. And sometimes when you have the wrong data for the question you are trying to answer, you have to admit that you just don't know the answer.

Quote:
Let’s address the problems—which a quick glance at Allegheny County air monitor data demonstrates extend beyond just the Liberty monitor/Clairton Coke Works.
I think we agree on this point--rankings aside, we do in fact have a variety of different air quality issues we should be working on.
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Old 11-24-2009, 01:34 PM
 
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Originally Posted by Fiddlehead View Post
Why not get mad as hell and get people to get your city out of the top 20, by any yardstick?!
The short answer is that if you use a bad "yardstick", you may not describe the problem correctly, you may design a less efficient solution as a result, and may ultimately think you have made more progress than you have actually made.
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Old 11-24-2009, 02:14 PM
 
24 posts, read 44,579 times
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Quote:
Originally Posted by BrianTH View Post
I don't think the methodology statement you quoted necessitates that conclusion, and again my spot-checking suggests they must have just used the Liberty monitor--otherwise they should have gotten an even higher three-year value. Note they are not just ranking metros, but also grading counties, and I believe what you are quoting is part of their letter-grade process.
The county data (which I think we agree is made up at least ~1/3 of non-Liberty monitor data) is used to establish the MSA rankings:
Quote:
Metropolitan areas were ranked by the highest weighted average among the counties within a given Metropolitan Statistical Area
(source (http://www.stateoftheair.org/2009/key-findings/methodology.html - broken link))

Admittedly the methodology section of the ALA report doesn't do a good job of describing the MSA ranking procedure. So if you're still not convinced, take a look at footnote 1, p.16 of the PDF report, which confirms this is the method they used specifically for the short-term particulate matter MSA rankings.
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Old 11-24-2009, 03:22 PM
 
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Originally Posted by kramhorse View Post
The county data (which I think we agree is made up at least ~1/3 of non-Liberty monitor data)
Not exactly. I'm not sure they used non-Liberty monitor data even for grading the counties by number of days in their various categories. Note that nowhere did they seem to specify they were just using the highest monitor for the annual data--they just did it. I'm not sure why we can assume they didn't do the same thing for the days.

And all that is independent from what they used for ranking the MSAs, because as I understand it the basis for that ranking was not their days-based grade for the relevant county, but rather the reported 24-hour Maximum averaged over three years, and my spot-checking of their reported value for that average suggests they must have just used the Liberty monitor.

Quote:
Admittedly the methodology section of the ALA report doesn't do a good job of describing the MSA ranking procedure. So if you're still not convinced, take a look at footnote 1, p.16 of the PDF report, which confirms this is the method they used specifically for the short-term particulate matter MSA rankings.
I'm not sure what PDF you are referencing.
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Old 11-24-2009, 06:29 PM
 
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Quote:
Originally Posted by BrianTH View Post
nowhere did they seem to specify they were just using the highest monitor for the annual data--they just did it.
They explain it here (http://www.stateoftheair.org/2009/key-findings/methodology.html - broken link):
Quote:
Counties were ranked by design value. Metropolitan areas were ranked by the highest design value among the counties within a given Metropolitan Statistical Area
What's a "design value"? From p.3 of this PDF:
Quote:
The annual standard design values shown here are calculated in accordance with 40 CFR Part 50, Appendix N (2006). The annual standard design value (i.e., the 3-year average annual mean concentration) is computed at each site by averaging the daily FRM samples taken each quarter, averaging these quarterly averages to obtain an annual average, and then averaging the three annual averages.
All annual data is from the Liberty monitor.

Quote:
Originally Posted by BrianTH View Post
I'm not sure why we can assume they didn't do the same thing for the days.
For short term, they do use the highest monitored value from any site on any given day. That's what I've been trying to say.

Quote:
Originally Posted by BrianTH View Post
And all that is independent from what they used for ranking the MSAs, because as I understand it the basis for that ranking was not their days-based grade for the relevant county, but rather the reported 24-hour Maximum averaged over three years, and my spot-checking of their reported value for that average suggests they must have just used the Liberty monitor.
It's way too long to excerpt it all here, but if you read the methodology section beginning with the heading "Description of County Grading System" and ending just before "Year-round particle pollution (Annual PM2.5)" they explain it. The short(er) version is that the highest 24-hour max from any county monitor on each day is placed in its corresponding air quality index category. Orange days are worth 1 point, red 1.5, purple 2; and maroon 2.5. Add them together, divide by 3 (for the 3 year time period covered). The more points a county has, the worse its ranking. The county with the highest score in each MSA is used in the MSA rankings. When they say "weighted average" they're referring to the AQI point system, not to a simple average of all 24-hour values in the 3 year period. Not a simple or intuitive system, but it does take into account monitor readings for each day

Quote:
Originally Posted by BrianTH View Post
I'm not sure what PDF you are referencing.
I mean the ALA report at issue, available here.

Anyone other than me and BrianTH still following this? Or have you all been bored/bewildered to death?
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