Commentary: Inconvenient Truths for Air Quality Expert Cahill

What Cahill Omits from Two Articles is Telling

On January 25, Dr. Thomas Cahill sent the Vanguard his own op-ed and two other articles, one of which was the December 30 LA Times piece, Freeway pollution travels farther than we thought. Here’s how to protect yourself, which we quoted from heavily yesterday.

Dr. Cahill has been citing the LA Times article as proof positive for his concerns about Nishi, and he also noted in an interview with the Aggie that Nishi is in some ways worse than near Highway 60, that some consider the most polluted site near a freeway in the nation.

But, as we pointed out yesterday, there are portions of the LA Times article that contradict Dr. Cahill’s conclusions, such as its view of the elevated section of roadway.  This is a point that Dr. Charles Salocks also disagrees on.

We noted, while Dr. Cahill has argued that the elevated section of the roadway makes Nishi more problematic, Dr. Salocks argues that “the elevated section of roadway will result in greater dispersion of traffic-related contaminants than would occur if the residences were at the same grade as the freeway.”

But a reader pointed out that the article that Dr. Cahill sent out is not a link, but rather a word document that he has saved.  But, remarkably, he has edited out several portions where he apparently disagrees with the document.

Here is the .pdf of the article Dr. Cahill sent out.

But after the paragraph that ends: “Make sure the model you choose is certified by California regulators.”  There is a chart in the article, but the next section, “Find physical barriers” is removed by Dr. Cahill.

Find physical barriers

If you can’t avoid living near a freeway, some locations offer more protection than others.

It’s better to live behind a sound wall, especially one with thick trees and plants extending above it. Such obstacles, though not designed to block vehicle emissions, can reduce pollution levels immediately downwind.

It’s also preferable to live near a freeway that is elevated above or sits well below your home. That vertical separation can help disperse pollutants. At-grade freeways, where lanes sit at the same level as surrounding buildings, are worse because they put vehicle tailpipes right next to people’s lungs.

If you live on a major boulevard, you’re better off when there are buildings of varying heights, parks and other open spaces that allow exhaust pollutants to disperse up and away from traffic, state regulators say. Avoid “street canyons,” blocks with masses of tall buildings that can trap pollution.

Later, he removes another section following the sentence: “When you’re in the car, roll up the windows and set your ventilation system to recirculate. That button can cut pollution to 20% of on-road levels.”

He omits the next section:

Stay away from interchanges, intersections and other hot spots

The risk to your health can be compounded if you live near multiple pollution sources. Avoid living close to highway interchanges and freeway ramps, which regulators and scientists have identified as hot spots that can hit residents with twice as much as pollution.

Keep away from major intersections and stoplights, where vehicles spit out a lot of exhaust when drivers step on the gas, and copper dust and other toxic particles when they hit the brakes.

“There’s basically a big cloud of fairly concentrated pollution when the light turns from red to green,” Fruin said.

Also factor in whether you live in a smoggy area. If you live near a freeway in a community with higher smog levels, like the Inland Empire, you could get a double dose of dirty air from traffic emissions piling on top of regional pollution.

The section he keeps, though, is kind of interesting: “Spending time in a car on the freeway can expose you to pollution levels five to 10 times higher than surrounding areas.”

The recommendation is “if you can, live closer to work, use public transit or take other steps to limit your driving time.”  But Dr. Cahill has never discussed the trade off of Nishi versus commuting from out of town.

The biggest omission is the first, where, again, the Times notes: “It’s also preferable to live near a freeway that is elevated above or sits well below your home. That vertical separation can help disperse pollutants. At-grade freeways, where lanes sit at the same level as surrounding buildings, are worse because they put vehicle tailpipes right next to people’s lungs.”

That is the opposite of Dr. Cahill’s view, and is clearly why he might have chosen to omit that section of article from the portion he shared.  As we note above, it is a view that Dr. Cahill does not share with Dr. Salocks.

Who is to say Dr. Cahill is wrong here?  But that’s not the point, the point is there is intellectual dishonesty in sharing an article, purporting it to be an article in its entirety, and then only sharing the portions that back up your claims and omitting portions that contradict them.

Dr. Cahill also shared a Huffington Post article called, “Even Breathing is a Risk in One of Orlando’s Poorest Neighborhoods.”  A cursory view of this article shows that, while there is no selective editing of sections, he does cut off the article at four pages.

There is some interesting information in the section not included, including a discussion of what Orlando plans to do.  They note that “the EPA doesn’t include ultrafine particles, the most adverse for health, in its index because they’re not a federally regulated pollutant.”

The article notes that Orlando plans to do its own “health disparity study,” with a goal of beginning this assessment within five years.

The Huffington Post reports: “But existing data already suggest that, in an area considered medically underserved, 41 percent of children suffer from chronic health issues. And residents say they don’t need to wait up to five years to know there’s a problem.”

What I find interesting here is that, in Orlando, there is clear evidence of health problems prior to a study.  In Davis, and along the I-80 corridor there is no evidence of such health problems.

Yesterday’s column pointed out the similarity between Nishi and east Olive in terms of location between the freeway and railroad tracks.  Dr. Cahill has argued that the elevated nature of I-80 at Nishi makes the threat there worse than the adjacent location.  Other research suggests otherwise.

We note there is existing data on health impacts from east Olive Drive that we can use, if not as a definitive guide, at least as a baseline.

Dr. Tia Will, a member of the Vanguard board and a retired physician, points out that opponents of the project are consistently downplaying the issue of epidemiology – the health impacts of known exposure along I-80.

She told me, “According to the county epidemiologist who gathered data on this question during the Nishi 1 debate at my request, there is no evidence of increased risk at this location as measured by ER visits for respiratory illness.”

Later she clarified: “I want to clarify what I have stated based on the information provided by the county epidemiologist. There is no evidence of increased health care impacts along the I-80 corridor from Vacaville to West Sacramento. This would imply that the risk along this corridor is not increased over that of the other neighborhoods in Davis.”

In fact, we have ample data here that people have lived in the east Olive Drive era since prior to the 1960s.  And yet, with very similar conditions, we see no evidence of health impacts.

So we note that there is a major difference between Nishi and the sites highlighted in these two articles – clear health impacts in the two articles, none at Nishi – in addition to a selective editing of contrary information of the Times article.

Some will continue undoubtedly to hang their hat on Dr. Cahill’s opposition to the project, but there is mounting evidence to the contrary.

—David M. Greenwald


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About The Author

David Greenwald is the founder, editor, and executive director of the Davis Vanguard. He founded the Vanguard in 2006. David Greenwald moved to Davis in 1996 to attend Graduate School at UC Davis in Political Science. He lives in South Davis with his wife Cecilia Escamilla Greenwald and three children.

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8 thoughts on “Commentary: Inconvenient Truths for Air Quality Expert Cahill”

  1. Tia Will

    Two points I would like to clarify about my previous comments:

    1. “we see no evidence of health impacts” – It is not that we see no evidence of health impacts. It is that we see no increased evidence of health impacts along Olive Drive and other nearby housing ( including my own neighborhood of OED) than we do other areas in Davis, in Vacaville, or any other neighborhood all the way to West Sacramento where we do start to see the increase.

    2. I have stated that opponents of Nishi in multiple conversations about the perceived increased risk at the Nishi site have disregarded, downplayed, trivialized or just plain shrugged when I mention the lack of epidemiological evidence. I should note that this includes Dr. Cahill ( who responded with a shrug)  in a recent one on one conversation. It is difficult for me to believe in the objectivity of a scientist who does not recognize evidence which does not support their own perspective even enough to acknowledge its existence.

      1. Howard P

        And what we see is evidence of ‘lies by omission’… no need to sugar-coat that… irresponsible for anyone… academics/professionals should be held to higher standards, n’est-ce pas?

  2. Alan Miller

    >But, remarkably, he has edited out several portions where he apparently disagrees with the document.

    I highly recommend everyone agree with every expert, and worship them as infallible Gods.

    1. Howard P

      Like… potential double-entendre… two edged admonition… actually, not ‘like’, but ‘love’.

      There are some who posit we should ALWAYS defer to thos “experts” who forward their views,and ignore other evidence/facts… several on this blog…

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