How to Muddy The Water on Fine Particulate Matter

One of the results of a career choice is that you meet other people in the same field and are in the habit of sharing information and comparing notes. This is true for me in the field of environmental protection, and it occasionally crosses over into my blogging habit. This is one of those times. This is my own opinion, on my own time, and has no bearing on the opinions of my employer or of my work on any related issues. It is a one-shot screed with one document as the focus.

A friend sent me a link to a recent issue of the Texas Commission on Environmental Quality‘s (TCEQ) informational publication Natural Outlook. It contains a piece on the subject of air quality standards for fine particulate matter (PM2.5 – particulates below 2.5 microns in diameter) and an argument against a more strict public health standard. This is in response to the EPA’s propsed lowering of the annual National Ambient Air Quality Standard (NAAQS) for PM2.5, and the document refers to the TCEQ’s public comment submission on this process, though it does not provide a link to those comments. It also give no details on how the annual standard is calculated or interpreted, and the relationship between that and the short-term or hourly standard. These are not minutiae, but the specific framework of the particulate matter health standard discussion.

On the face of it I have no problem at all with disagreement on public health standards. As a professional in the field I know that there is a need for disagreement, discussion, and a tolerance for diverse viewpoints. I also believe that a well informed populace is the best kind of populace, and that they can make better decisions, better process information, and make better personal decisions regarding public policy. Some of those personal decisions might take place in a voting booth, for instance.

That is where I began to have some concerns about the document in question. I believe it is chock full of misleading information and I believe it serves to confuse the reader about the public policy process and the science behind it. It also seems to cherry-pick over where to provide a technical discussion, and where to treat the reader a a pure layman.

The first paragraph is a basic description of the pollutant. No problem there. The article even includes an info-graphic depicting particle size relative to a standard-issue human hair. Enjoy it, because it is the only graphic you get. We then get a description of the change in the air quality standard: 15 ug/m3 to 12 ug/m3. OK, not much to freak out about yet, except the lack of context for an annual standard versus a 24-hour short-term “event” standard.

From here on out things get weird. TCEQ participated in the public comment period? OK, how? Where is the text of the comment? After that we find out that “many” studies have taken place… involving “large” groups of people… again, no references, citations, or details. This is equivalent to “some say”, a strawman alert if there ever was one. Then we find out that particulate matter is naturally occurring, which is true. And that it can be composed of many types of material, and be generated from many processes, which is also true. But pollen and spores are given as examples of naturally occurring PM2.5, which is not true.  Pollen and spores are larger than 2.5 microns, and in only a few cases are they smaller than 10 microns, so they fall almost entirely out of the regulated particulate matter discussion of PM10 (less than 10 microns) or PM2.5 (less than 2.5 microns). We also find out that PM2.5 is not regulated by composition, which is also true… But then then the penny drops when we find out that Texas thinks the problem might be regional. “The health effects that have been linked to PM2.5 exposure in human studies also vary by region. Multiple studies report potentially increased levels of disease possibly linked to PM2.5 in the eastern United States, but the evidence is inconclusive for the central and western portions of the U.S.“. Rough translation: “Yankee Problem”.

One reason for the enhanced focus on the “eastern United States” may be that states in the northeast US found out very early in the PM2.5 monitoring process that they are heavily impacted by airborne PM2.5 transported from large combustion sources in the mid-west. The upshot is that regulating sources within a state’s borders may be, and has been, insufficient to meet the ambient air quality standard. In an effort to better define the sources of particulate matter, Northeastern states have conducted studies where particulate matter is collected and analyzed to determine the type and content of the actual particles. These states operated a monitoring network targeting the quantity and the composition of particulate matter, and did back-trajectory analysis to attempt to identify potential sources. They found out that you can tell a lot about the source of the particles by analyzing their composition. Another point that the TCEQ presentation misses is that there is over a decade of research into PM in many areas of the US, not just the eastern US. Since no specific studies are cited we can’t know how deeply they have investigated the issue. What we can conclude is that instead of deciding that a speciated (composition analysis) PM study might be useful in their region, they seem to be indicating that the problem itself is regional, not the response to the problem.

Then we are treated to a very odd health effects discussion, where the “London Smog” incident of 1952 is the sole example cited, despite the fact that there are many more current examples of PM-spikes, many in the US, and the London example predates any form of scientific PM measurement. The fact that it excludes any of the studies conducted in the US over the past 20 years, including the studies that made the primary case for PM-related health effects in North America, and form the basis for the original PM2.5 standard, is either perplexing or predictable.

There are a plethora of  studies that have shown a relationship between elevated fine particulate concentrations and increased hospital admissions and increased mortality in sensitive groups like people with pulmonary and respiratory problems. This kind of study has been repeated worldwide, both in active studies and in analysis of historical data. [In the news this very day, we could discuss the potential of China becoming little more transparent with its health data, and whether we would see a spike in admissions and mortality associated with their current particulate pollutions crisis]

This is followed by a very balky discussion of dose-response. We are taken back to Paracelsus… and the 14th century, and an example involving aspirin. Then we are told that PM levels are declining, since the year 2000, with no mention of the fact that “since 2000” corresponds to the implementation of the original EPA PM2.5 standards and the resulting requirement for PM2.5 controls. They just declined. That’s all.

The kicker is the introduction of our good friend Epidemiology! Yes, the “science” that couldn’t prove health impacts from either tobacco or asbestos [that required lawyers, with access to internal communications at places like J.R. Reynolds and Johns-Manville, with admissions that they knew of the health effects and were making business decisions based on them] is here to take the fall for lack of evidence on PM-related health effects.

At this point the damage is done. The reader has been set up for failure, having neither the information or the tools to dissect the final broadside against another crop of unnamed, unreferenced health effects studies that don’t measure up to the situational standards of the TCEQ.

I know that I am riding a fine line, and that it sounds like I am just out to blast some good-intentioned tech writer at TCEQ. I am not.What I am against is pamphleteering in the name of public health policy. I believe that someone intended this document to be informative, and that someone else had a lower bar for “informative”. There is an argument to be made against constantly tightening air quality standards in the absence of health effects evidence. That argument is made on the basis of sound science, and the arguer might have to get their hands dirty with actual research, or funding of actual research. At the very least they would prepare a peer-reviewable analysis of the current science and be available to defend their conclusions. What we have here is what I personally believe to be a good example of bad public communication. The reader has no chance to adequately understand the framework of the discussion, the details of the discussion, or the science behind the discussion.

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