Sunday Commentary: Do We Gain Anything from Additional Air Quality Study of Nishi?

Critics of the Nishi project continue to raise the question of, if there are no problems with the Nishi site, why not just do the studies that Dr. Thomas Cahill is asking for?  But the question I keep asking – to which there has been no satisfactory answer regarding the limited duration of residencies at Nishi – is what level would have to be present in order to create a problem?

That would seem to be a fundamental question.  Because, despite claims by Thomas Cahill that this is one of the most polluted sites in the nation, clearly the data we have doesn’t suggest a huge health threat.

How do we know that?  Because the Draft EIR references the work done already to sample air quality at a location that was near and not on the actual site.  Critics have complained that those findings are problematic because the 10-day measurement wasn’t representative of the possible range of conditions and, again, wasn’t performed on the site.

The EIR notes that “the concentration of diesel PM on the Nishi site approximately 300 feet from the edge of I-80 was estimated to be approximately 0.57 micrograms per cubic meter (μg/m3). This estimate is based on the particulate measurements conducted near the Nishi site in February 2015.”

So, while clearly neither Dr. Cahill nor other critics believe that level of exposure is above the critical level, they also have yet to define what the critical level is for a few years of exposure and, until and unless they do that, any attempt to further study Nishi is akin to hitting a moving target.

In his op-ed this week, Thomas Cahill continues to raise issues that Nishi is one of the most polluted sites in the nation.

But there are reasons to be skeptical of these claims.  Data compiled over a 10-year period suggests wind patterns would not produce the worst case scenario most of the time, and a question that I
continue to ask is how high do the particulate matter levels have to be in order to actually cause problems over such a limited exposure time?

They base risk levels to a 70-year exposure, but most people at the proposed Nishi site will live there for one year, with a possibility of two to three years at most.

The other problem is that reaching Dr. Cahill’s threshold appears to be akin to hitting a moving target.

In an email exchange a decade ago, Dr. Cahill told Tim Ruff the “bad news” about conditions at a huge rail freight station.  But Nishi isn’t building by a huge freight station, which would be worse “because the engines are left idling.”

Then Dr. Cahill writes that “it is the 24 hr/day factor that drives the bad news for residences, and most of that is indoor. It is possible with very minor modifications of heating/cooling systems to make the air inside the houses essentially pristine. We did such tests as part of the vegetation study, and in a test, reduced diesel/smoking car exhaust in Arden Middle school by 70%.”

Moreover, in a 2007 study that Dr. Cahill was a part of, they found that “vegetation near very fine particle sources can be effective in removing some of the most toxic particles in the air before they get mixed into the regional air mass.”

The opponents and critics of Nishi keep calling for more testing on the site.  But is testing really going to resolve the problems?

For example, Charles Salocks in analyzing 10-year wind direction data, found, “Worst case scenario winds (SW) occur very infrequently (5% of the time).”

Second, toward my question about exposure time, “The health assessment in the EIR is based on an assumption of a residency of 70 years with no mitigations. (The) typical residency at Nishi will be 1-3 years, not 70. This alone reduces long-term health risk by at least 95%.”

He also found that the mitigations will further reduce exposure.

“A 100’ x 2000’ peripheral greenbelt and an internal ‘urban forest’ will filter particulates from the freeway.  Future residents of Solano Park, and other nearby properties, will also benefit from this measure.  Air filtration systems will further enhance indoor air quality where students spend most of their time,” the professor wrote.

Then there was the presentation by Don Shor.  He found that the urban trees play a huge role in reducing pollution and improving air quality by as much as 16 percent.

Among the studies cited:

• Trees planted outside the home can provide substantial reductions in PM inside the home (>50% reduction).
• A field study in Sydney, Australia, showed a 42% reduction in particulate matter from sites with more trees.
• Cahill (2008) found that redwood vegetation removed 79% of 0.17μm diameter particulate matter in a wind tunnel experiment.
• Further wind tunnel research used by Dr. Cahill estimated very high filtration of very fine particles by two species of conifers (redwood and deodar cedar), from 79 – 99%.
• As of April 2017 the state Air Resources Board now includes vegetative buffers among their recommended strategies that reduce traffic emissions.

So what we have now is a growing body of counter-evidence.  Data on the wind directions suggest that the worst case scenario only happens 5 percent of the time – we have ten-year wind studies that won’t be impacted by more on-site study.

We have research on mitigation measures such as air filtration.  Once again, additional on-site studies will not better inform that.  A decade ago Dr. Cahill said filtration units could reduce particulate by matter by 70 percent, and the EIR with more modern techniques has pushed that higher.

We have research on the impact of vegetation – including a decade-old study from Dr. Cahill himself that concluded: “[V]egetation near very fine particle sources can be effective in removing some of the most toxic particles in the air before they get mixed into the regional air mass.”

If that is the case, then we won’t know what level of particulate matter actually reaches the residents until and unless the site is built and tests are done then.

Finally, as Dr. Salocks has pointed out, echoing our point, the health assessment is based on a 70-year residency assumption, and, if the typical residency at Nishi is more like one to three years, that alone will reduce any long-term health risk by a huge amount.

If all that is true, how is air quality testing going to help us answer the problem any more than we have it right now?  The mitigation measures, the vegetation, the wind directions and the exposure time are all crucial variables and none of them will be better informed by more testing on-site.

So my question remains, what do we actually gain by doing further studies?  Is this just a delay tactic by opponents of the project?   Can we establish a level of danger prior to additional study?

A telling answer from Dr. Cahill may explain his view, though, and whose view seems captured here: “Even one preventable death is not acceptable.”

His allowable risk level is therefore not merely very low, but zero.  If that is the case, why bother with further air quality studies – he already has his answer.  The risk isn’t zero, it’s just very low and it can be mitigated.

Until someone wants to define what the acceptable risk is, there is no point to any further study.

—David M. Greenwald reporting