New Report Highlights the Health Risks of Living Near Freeways, Renews Concerns about Nishi

Back in 2016, one of the issues that arose during the Measure A campaign was whether the air quality levels at Nishi should preclude residential development on the site.

Thomas Cahill, a respected Professor Emeritus and an expert on air quality, expressed concerns about “the viability of the Nishi property for residential use.”

In short, he argued that Nishi is directly downwind from I-80 with a number of air quality factors, and in close proximity to a heavily-trafficked rail line as well.  He argued, “These aerosols are closely tied to decreased lung function in children living near Los Angeles freeways and a greatly enhanced death rate from heart attacks in the southern San Joaquin Valley (and to a lesser extent in Sacramento).”

He argued, “These reasons form the basis of my opposition to single family or condominium residential use that would expose sensitive populations, especially children and the elderly, to the diesel exhaust and the ultra-fine metals from 1-80 vehicles, especially during braking.”

As such, he recommended a two-year study period for the aerosols at the Nishi property, he proposed an “apartment dwelling proposed use (of) the technique of low pressure drop ultra-filtration,” and he suggested that, prior to residential use, “the buildings be evaluated for effectiveness of the mitigation efforts, and modifications made if necessary to improve air quality to at least City of Davis average in-home values as measured near City Hall.”

Nearly a year later, Nishi was narrowly defeated, and the future of a Nishi project remains unknown as no new project has emerged.

However, last week the LA Times published a major new story which reports, “L.A. keeps building near freeways, even though living there makes people sick.

“For more than a decade, California air quality officials have warned against building homes within 500 feet of freeways,” the Times writes.  “And with good reason: People there suffer higher rates of asthma, heart attacks, strokes, lung cancer and pre-term births. Recent research has added more health risks to the list, including childhood obesity, autism and dementia.”

Not surprisingly, local officials have largely ignored the warning and allowed an increasing amount of home building near traffic pollution, according to a full analysis of census data and building permits by the LA Times.

They write, “In Los Angeles alone officials have approved thousands of new homes within 1,000 feet of a freeway — even as they advised developers that this distance poses health concerns.”

In fact it gets more ironic, as they found that public funding, “including millions of dollars from California’s cap-and-trade program to cut greenhouse gas emissions, are going to developers to build new homes in freeway pollution hot spots.”

The Times found, “More than 1.2 million people already live in high-pollution zones within 500 feet of a Southern California freeway, with more moving in every day. Between 2000 and 2010 — the most recent period available — the population within 500 feet of a Los Angeles freeway grew 3.9%, compared with a rate of 2.6% citywide.”

The Times cites LA Councilmember José Huizar, who called freeway pollution an urgent and complex problem and has asked the city to establish buffer zones.  He called for a “comprehensive, citywide study of development near freeways that would analyze all impacts of limiting development around freeways.”

On the other hand, Mayor Eric Garcetti acknowledged growing up near several freeways and that many of his family have had cancer, but he opposes new restrictions and instead believes “improving air-filtration, building design and tailpipe emissions are a better way to reduce risks to residents.

“I take this stuff very seriously, but I also know that in looking for housing we have a very constricted city,” he said.

The Times notes that “a prohibition on building within 1,000 feet of freeways, for example, would cover more than 10% of land currently zoned for residential construction in the city.”

Part of the problem in LA, as we saw in the Nishi campaign, is that the science is not settled.  Discussions that the Vanguard had with Thomas Cahill on this subject focused on risk assessment as much as anything else.  Professor Cahill wanted the city to do the analysis before building the units – in the middle of a campaign, that was an impossible ask.

At the same time, the city has taken steps to keep the door open to a new Nishi proposal – and yet there seems to have been little incentive to evaluate the actual risks.

As the LA Times notes, “Scientists have long known that polluted air cuts lives short. But pinpointing the harmful agents in traffic pollution is difficult because it’s a stew of ingredients including toxic combustion gases, microscopic soot particles, compounds from worn tires and dust from vehicle brake pads. Recent research has narrowed in on one component of special concern: ultra-fine particles, pollutants in freshly emitted vehicle exhaust that can be five to 10 times higher near traffic.”

The particles are “so tiny they are hard to capture with pollution controls or filters. Scientists suspect ultra-fine particles are able to pass through the lungs and into the bloodstream, where they may harm the heart, brain and other organs. Yet they remain unregulated by state and federal authorities.”

The Times writes, “That emerging science has raised concerns that decades of government regulations, aimed at curbing smog that builds up across vast urban areas, are not sufficiently tailored to the more localized problem of roadway pollution.”

In a long-term study, “USC researchers have for more than two decades measured the lung capacity of thousands of school children across Southern California. They found that children growing up near major roadways have higher rates of asthma and other respiratory illnesses, including deficits in lung function that can be permanent and lead to a lifetime of health problems.”

The Times notes, “Even in communities with cleaner air, such as Santa Maria near the Santa Barbara County coast, children living near traffic had the same lung function loss as those in Riverside and other smoggy inland areas, the scientists found.”

One of the big questions that arises is not whether exposure to these particulate matter is harmful to the health of residents, but how to place that within an overall risk assessment.

Page 62 of the final EIR on Nishi explained that the consultants compared air pollution health risks to those within other areas of the state.  They write, “South Coast Air Quality Management District (SCAQMD) conducted a district-wide evaluation of air pollution health risks in 2014, finalized in May 2015. The average air pollution health risk was estimated to be 1,025 per 1,000,000 residents (SCAQMD 2015). The report also estimates that diesel particulate matter represents approximately 80 percent of the total air pollution health risk or 820 per 1,000,000 residents.”

Here they found that the DPM (Diesel Particulate Matter) health risk, in the unmitigated form, “at the Nishi site was determined to be approximately one-fourth of that.”

They added, “The Sacramento Metropolitan Air Quality Management District (SMAQMD) estimates that the reasonable worst-case level of health risk from free-way generated toxic air contaminants is approximately 919 per 1,000,000 residents for a residential dwelling located just 50 feet from the busiest freeway in Sacramento County.”

Gary Jakobs, the EIR consultant, told the Vanguard that “a health risk, as presented in the Nishi EIR, is most easily and readily defined as the possibility or estimated probability of adverse health effects (e.g., illness, injury, or disease) from a person’s exposure to toxic air pollutants. The numbers presented in the EIR are a quantitative measure of the probability of such a risk.”

He noted, “A health risk is not a guarantee that a specific number will contract a particular adverse health effect, but rather an assessment of a particular condition (e.g. proximity to elevated freeway) and the probability that individuals subject to that condition could experience an adverse health effect.

“It is true that the conditions at the Nishi site do not make it the worst place to live in the state,” Mr. Jakobs stated, adding that “the relative health risks within many of the urban areas in the state are likely much greater.”

He also stated, “It is important to note that ultra-fine particulates (UFP) is not generally assessed as part of current health risk assessments, and there are no established ambient air quality standards (national or state) for UFP, as of yet.”

Back in January of 2016, Robb Davis, then the Mayor Pro Tem, himself a public health professional, argued that the risk assessment at Nishi was actually quite low.

Section 4.3 of the Draft EIR, for example, notes, “One common metric of health risk is the number of additional cancer cases that may occur in the population exposed to a particular TAC [toxic air contaminant], or located in an area exposed to TACs in general. This is typically reported as additional cancer risk per million people.”

Here the EIR notes that, according to the American Cancer Society, “the lifetime probability of contracting/dying from cancer in the United States is 43.3%/22.8% among males and 37.8%/19.3% among females.  In other words there is a lifetime probability that over 430,000 per 1 million males and over 370,000 per 1 million females will develop cancer over their lifetime.”

In his comments to council, Robb Davis noted that the lifetime risk of respiratory cancer was about 10 percent or 100,000 in 1 million.

The numbers shown above are on the magnitude of 1025 per 1 million, a far lower added risk than the overall risk.

But what we are learning is that it might not just be Nishi that is at risk.  The Times writes, “Public health officials have long warned that traffic pollution can drift well over 1,000 feet from traffic — and more recent research suggests that it may waft more than a mile.

“Yet it took lawsuits and a nationwide mandate from the U.S. Environmental Protection Agency to force Southern California air quality officials to begin regularly measuring pollution near Southern California freeways in 2014.”

Davis does not have good pollution measuring levels at Nishi.  But what LA found should be quite alarming:

“The first readings confirmed that people near freeways breathe higher levels of the exhaust gases nitrogen dioxide and carbon monoxide. Then, in 2015, the South Coast Air Quality Management District detected the region’s highest concentrations of fine particulate matter at a new monitoring station 30 feet from the 60 Freeway in Ontario. The findings added compelling evidence that traffic emissions are piling on top of regional smog, hitting people near freeways with a double dose of pollution.”

The Times did their own study and found, “Pollution readings near the freeways were three to four times higher than in neighborhoods at a distance from traffic.”

The question is if the city wants to go ahead with another proposal at Nishi, what should they do?

Dr. Cahill’s final comment to the Vanguard last year was the need to err on the side of caution – or what he would call the “precautionary principle.”

He said, “After getting all the scientific information possible I would have to make my judgment with the ‘Precautionary Principle.’ This requires that in the face of uncertainty, I would have to choose on the basis of the most conservative estimate of the impact, which is almost always lower than  the scientist’s bottom number. In Davis, this means that (if) there is any reasonable chance that I and my colleagues are right, I would have to reject residential use and maximize protection of workers in commercial or research facilities. The best way to solve this is to have better data, covering at last a year and including all the most toxic components. This is what I recommended in Jan 2015.”

—David M. Greenwald reporting

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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29 thoughts on “New Report Highlights the Health Risks of Living Near Freeways, Renews Concerns about Nishi”

  1. Tia Will

    Professor Cahill wanted the city to do the analysis before building the units – in a middle of a campaign, that was an impossible ask.”

    I think this is an excellent example of how our current process of the developer acquiring property, investing large sums of money into a project that is then presented to the community for consideration is inadequate since it creates the above, unnecessary adversarial situation.

    Imagine how much more efficiently a project might proceed as follows:

    1. Developer has interest in a project in a given location

    2. Presents concept to city and any regional stakeholders, in this case including the university and actively solicits commentary from any local/regional experts and community at large to elicit their concerns.

    3. If safety studies are recommended, developer considers whether or not said studies are economically feasible. If not, he will have saved large sums on developing a project that will likely be defeated. If undertaken, this step will ensure that “last minute” safety concerns will not sabotage a project as was almost certainly a factor in Nishi.

    I know that this is not our current model, but what would we have to lose in a situation in which no Measure J/R has passed recently , and in which attempts by the developer to modify a project after presenting it are framed by some members of the community as a “bait and switch” whether accurate or not ?

  2. Greg Rowe

    This reminds me of an experience I had while working on economic development and environmental issues for the Oakland Chamber of Commerce, 1996-99.  City Council District 3 was represented 1996-2012 by Nancy Nadel, a former USEPA environmental engineer. That district is adjacent to the Port of Oakland, where docked ships would continually run their diesel engines.  The docks were close to the district’s lower income neighborhoods, primarily occupied by African Americans.  It is also traversed by I-80, which passes above the district’s lower income neighborhoods before crossing the bay.  As a result, the residents of those neighborhoods were exposed to high levels of fine particulates in diesel emissions and the braking action of heavy-duty trucks.  Based on her professional expertise, Nadel was able to produce data showing that children in those neighborhoods consistently had higher levels of respiratory disease than children living elsewhere.  While not precisely a comparable situation to Nishi, the distances between those residential areas and the emission sources were not all that much different than the distances from such sources at the Nishi site.  Given this information, the alternative development approach suggested by Tia Will makes a lot of sense to me.

  3. Alan Miller

    Thomas Cahill, a ‘respected’ expert, says the risk may be quite high!

    Rob Davis, a health care professional, says the risk is actually quite low!

    Like I always say, trust the experts!!!

    1. David Greenwald

      While the science doesn’t seem quite set yet, the emerging view probably favors Cahill’s more cautious approach.  What I would like to see is some studies along the lines of what the LA Times did – if the council wants to see this project developed, I don’t quite understand why that wouldn’t become a priority.

      1. Ron

        David:  ” . . . if the council wants to see this project developed, . . .”

        Then they’ve got some explaining to do, especially to the majority of voters who rejected it the first time.

        On a more serious note, I sincerely hope that the city isn’t even THINKING of funding an air quality study (using public funds), to subsidize a proposed private development. 


        1. David Greenwald Post author

          They don’t have any explaining to do. The LRDP response letter made it very obvious they want the door open for a new proposal.

          I would also suggest that if they were to do an air quality study, it should be a good deal broader than just at Nishi. I don’t know that the city is the appropriate agency to do this, there are other jurisdictions that would seem more appropriate. Given that the LA Times did their own study, it doesn’t seem like it is that expensive an undertaking.

      2. Howard P

        David… suggest you clarify the tone, and statements in the article, where you seemed to be talking about ‘a new proposal for for the Nishi site, vs. your 11:43 post where Ron quoted you seeming talking about ‘the same or similar project‘, on the site.

        You are the only one who can clarify what you meant/intended.

        Just a suggestion… my guess is your article was given much more thought than your subsequent post.

        1. David Greenwald Post author

          Howard: It’s not really a huge mystery here, part of the LRDP response by the city was to keep the possibility of Nishi on the table.  There is no new proposal at this time.  But if council wants a project here – and from the LRDP discussion they do – then it would seem incumbent on them to take this time when there is no project and thus no clock ticking to get some air quality readings and figure out if there is a potential health hazard for Nishi.

      1. Tia Will

        Not that I know of, but what we do know about Olive Drive is that there is no increase in ER visits for respiratory illness from that neighborhood as compared to the remainder of Davis, but such an increase is seen in close proximity to the freeway in West Sacramento.  What would be useful is air samples from Olive Dr. for comparison to Dr. Cahill’s samples. If the Olive Dr. samples were similar or higher in contaminants than the Nishi site, it would be one small reassuring factor with regard to the relative safety of the site as regards respiratory illness. Obviously this could not be extrapolated to cardiovascular disease, pregnancy outcomes, or autism, but that data could also be obtained epidemiologically as well.

        1. Ron

          Tia:  ” . . . there is no increase in ER visits for respiratory illness from that neighborhood as compared to the remainder of Davis, . . .”

          Just wondering – would respiratory illness necessarily require more visits to an ER?  Also, in the case of Olive Drive, is there sufficient information overall, to arrive at a conclusion (e.g., an actual study)?

      2. Alan Miller

        Have we taken air quality samples on Olive Drive?

        Didn’t stop the speculation on Nishi.  Olive Drive is also wedged between the freeway and the railroad — in fact, it is even more pinched between them.  No one seems to care about the — the — CHILDREN!!!

  4. John D

    This is a great conversation.  Funny that nobody is talking about/protesting the horrendous bottleneck design of Eastbound I-80 that is now placing inordinate air quality burdens on Davis and environs.

    What about parallel implications for organic farming on this same property?

    Anybody working on/talking about the root cause of the problem?

  5. Tia Will


    I would shorten your response to “too many drivers”. We used to have one poster here who’s solution was to add more lanes. I would hate to see that revised in response to the “using too small of a road” portion of your comment.

    1. Ron


      Point noted.  When more lanes are added, it ends up subsidizing more sprawling development, regardless.

      But, I do think that private transportation (in some manner) is here to stay.  (Public transportation is well-suited for daily commuters, traveling to areas that employ large numbers of workers.)

  6. Ron

    David:  “But if council wants a project here – and from the LRDP discussion they do . . . “

    Fortunately, it’s not up to the council.  However, they do have a choice regarding whether or not to throw the city into turmoil, again.  (Assuming that the developer wants to try, again.)

     David ” . . . – then it would seem incumbent on them to take this time when there is no project and thus no clock ticking to get some air quality readings and figure out if there is a potential health hazard for Nishi.”

    It’s incumbent upon the owner to pay for air quality studies on the site, assuming they want to try this again.  I’m sure that it would be “popular” among residents if taxpayer funds (from any public source) were used to subsidize a proposed, private development – especially after the proposal was defeated the first time that it was attempted.

    1. David Greenwald Post author

      So you view the council putting forward projects for the voters to consider tantamount to “throwing the city into turmoil”?

      I very strongly disagree with you that it’s incumbent on the owner to pay for air quality studies especially when there are likely other health concerns in other places that you appear not to give a crap about because there is no proposed project there.

    2. Don Shor

      It’s probably worth pointing out that Nishi was to be a collaborative process between the city and the developers, with shared risks, responsibilities, and benefits. I think the city actually initiated the process.

      1. Ron


        If the city is a true “partner” (and paying for part of the cost), then perhaps it’s not unreasonable to ask a developer to disclose and share expected profits that would result from a proposed development.


  7. Ron

    David:  ” . . . especially when there are likely other health concerns in other places that you appear not to give a crap about because there is no proposed project there.”

    Not sure if your comment above was subsequently removed/deleted.  (Not seeing it, after logging in.)

    Nothwithstanding the “civil tone” of your comment (and the assumptions you’re making), it’s a lot easier to avoid development in an area with potential health concerns in the first place, vs. trying to mitigate concerns in an already-developed area.

    Regarding already-developed areas, this reminds me of developments that are built in a flood zone, and then requiring taxpayers to subsidize the development via expensive levee systems (and, figuratively/literally “bailing out” those residents using taxpayer funds again – when the levee inevitably fails, anyway).

  8. David Greenwald

    My post is just above yours.  My view on the subject is that we ought to study the air quality across the board including at Nishi.  For the most part I continue to view this issue as your attempt to stop development rather than any real concern for people’s health.

    1. Ron

      David:  ” . . . I continue to view this issue as your attempt to stop development rather than any real concern for people’s health.”

      Certainly your prerogative, to speculate.

      One could view this as your attempt to promote private development using taxpayer funds, rather than any real concern for people’s health.

      I sincerely doubt that you’d be advocating for a taxpayer-funded, “across-the-board” air quality study, if you weren’t interested in promoting development at Nishi.

  9. Todd Edelman

    Have to dig further generally and specifically, but curious how much concern there has been about sound emissions from I-80 within the context of this project, and more generally, i.e. inclusive of 113.

    In a relatively optimistic scenario highway noise is mitigated to some extent by improved pavement surfaces and any vehicles operating in electric mode, but there is still considerable noise – and vibration – from tires and the wind resistance of vehicles.

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