One of the key questions I have been asking since we have started the air quality discussion with the Nishi project has been what these risk analysis rates actually mean. For instance, if we talk about a 197 in one million increased cancer risk, over what period of time is that over?
It turns out that the answer was there, we just had to find the right document, in this case the air quality analysis at New Harmony, which turns out to be quite a bit lower than the risk at Nishi.
However, the duration of exposure is incredibly important because, in the case of the current proposal at Nishi, we end up with a development where the inhabitants are going to primarily be student renters and therefore most of them will be there anywhere from one to three years.
Sunday’s commentary on Nishi’s air quality issue attempts to forge out some ground to put this issue to rest. While there are some reasonable concerns about the air quality, given the limited duration of exposure at a student rental housing project, I tend to believe these are more about stopping the project than exposing legitimate health concerns.
But a key piece that has been missing has been an understanding of what the risk factors mean.
Well, now we have a greater understanding and we pulled up the report from the city-hired consultant on New Harmony. The developer had hired LSA Associates to do an HRA (Health Risk Assessment) on the project.
The figure ultimately derived by these types of studies represents a “maximum potential cancer risk” and “a reasonable worst-case estimate for the nearest point of the project parcel containing the multi-family homes…”
The consultant notes that LSA “concludes that the actual cancer risk would be lower than the values they calculated because…”
First: “The maximum potential cancer risk is based on the assumption that an individual is exposed to the outdoor air concentrations computed by the dispersion model for 24 hours per day throughout
a 70 year lifetime.”
That’s the key piece I was looking for. If that’s true, then even a five-year exposure would be negligible. And, while some have pointed out I am only looking at cancer risks, the reality is that’s what we appear to have data on AND the same principle should still apply for other health risks – it should be a function of concentration over time, not just concentration.
Second, they find that a resident occupies a specific residence an average of nine years and in the same general area for 30 years. For apartments, that is a good deal less, “averaging between 5 and 15 years.” And of course, we expect student apartments to be even less than that. Again, I would say one to three years, but it would now appear that even going up to five and 10 years is not going to be a huge problem.
Finally, they note that “people spend most of their time indoors, averaging 22.5 hours per day, not outdoors. TAC [toxic air contaminant] levels indoors are typically one-third lower in residences and schools than outdoors, and almost one-half lower in offices than outdoors.”
This is helpful information for sure. It puts the risk analysis into perspective – it is the assumed risk over the lifetime of exposure – a maximum possible risk. Now, in the case of New Harmony the risk was about nine in a million, and here it is somewhere around 200 in a million for cancer.
It was pointed out on Sunday that we continue to ignore the risk of other factors. For instance they cite the Bay Area Air Quality Management District (BAAQMD) ordinance: ”Scientific studies show that exposure to particulate matter from air pollution leads to significant human health problems, including: aggravated asthma; chronic bronchitis; reduced lung function; irregular heartbeat; heart attack; and premature death in people with heart or lung disease. Exposure to air pollutants that are carcinogens can also have significant human health consequences. For example, exposure to diesel exhaust is an established cause of lung cancer.”
The reason I have looked at cancer risk is that is the quantifiable data which appears to be available. The question I would have is what are the risk factors for the other possible impacts of TAC pollution?
In this case, unlike New Harmony, the risks were found to be “significant.” The recommendation was not to not build in this area, but rather employ a series of mitigation measures designed to lower the risk.
Ultimately the EIR is a disclosure document rather than a prohibitive one. They found that the air quality impact is significant but partially reducible through a series of mitigation measures.
As the consultant report cited demonstrates, most people spend most of their time indoors (if they are home) and not outdoors. They have found that indoor levels are far lower (one-third) than outdoor levels. Couple that with the relatively short period of exposure (compared to the 70-year baseline) and the real health impacts here are probably less than alarming.
With that said, I would still like to get a better sense for the other risk factors for other impacts listed above, and the upper level TAC levels for the site. Right now it would appear that, even at the upper bounds, you are still looking at an increased risk of less than one in 5,000 over a 70-period of exposure.
—David M. Greenwald reporting