Eric Jaffe at CityLab discusses my post from Monday:
The ever-thought-provoking David Levinson posed a question at his Transportationist blog earlier this week that’s worth a longer look: Are you more likely to die from being in a car crash or from breathing in car emissions? If your gut reaction is like mine, then you’ve already answered in favor of crashes. But when you really crunch the numbers, the question not only becomes tougher to answer, it raises important new questions of its own. …
| road injury + other transport injury | total air pollution | |
| Deaths: | 15 | 36 |
| DALY: | 797 | 624 |
| Years of life lost: | 653 | 565 |
Just as estimating deaths from air pollution is inexact (no death certificate says “air pollution” as cause of death; instead rates of outcomes like heart attacks are elevated slightly in the presence of air pollution), so too it is inexact to estimate contributions from specific sectors (e.g., road transport) to the air pollution total. Some PM2.5 is emitted directly and some pollution forms in the atmosphere from chemical reactions of precursor emissions; the latter type (called “secondary PM2.5”) is harder to attribute.
The most useful number to look to, from an overall health standpoint, probably is the DALYs, since that number includes both mortality and morbidity (death and disease).Accounting for uncertainty, to a first approximation the numbers above are roughly comparable to each other, for the two causes.
In the early twentieth century, people fled over-crowded cities for suburbs, or at least lower-density areas of the city, in part because of the poor environmental quality. While water quality in cities has significantly improved, and sewers are sanitary, and horses no longer befoul our streets, today still, air quality in cities is usually worse than in lower density areas.
Recent research by University of Minnesota colleagues reports:
Results: The proportion of physically active individuals was higher in high- versus low-walkability neighborhoods (24.9% vs. 12.5%); however, only a small proportion of the population was physically active, and between-neighborhood variability in estimated IHD mortality attributable to physical inactivity was modest (7 fewer IHD deaths/100,000/year in high- vs. low-walkability neighborhoods). Between-neighborhood differences in estimated IHD mortality from air pollution were comparable in magnitude (9 more IHD deaths/100,000/year for PM2.5 and 3 fewer IHD deaths for O3 in high- vs. low-walkability neighborhoods), suggesting that population health benefits from increased physical activity in high-walkability neighborhoods may be offset by adverse effects of air pollution exposure.
Over the coming decades however, hybrid-electric and electric vehicles are likely to be more common, if not the only vehicles allowed on city streets. The smell of the city will change. EV cities will be less polluted and much nicer, and thus more attractive than earlier polluted cities, or cities without such vehicle-type regulation. It will come a time that not only will cities be better for the global environment, resulting in less overall carbon emissions than lower density areas with greater distances and fewer shared walls, but they will be as good (if not better) for the individuals residing in them, with less overall pollution per capita and perhaps lower pollution intake than suburban areas.
On February 1 (at 6:05 am) I found a BART card with $1.35 of money still on it on Sacramento Avenue near the North Berkeley BART station. I picked it up and used it. In economics there is the parable that you never find $10 bills on the ground, because someone would have picked it up already. And that of course is true in a steady state where no one ever drops another $10 bill. Eventually they will all be picked up. But if someone does drop a bill, it is on the ground until someone picks it up.
The most charitable view of emissions, and it doesn’t matter which pollutant (e.g. the EPA criteria NOx, SOx, VOC, CO, PM10, PM2.5, or even CO2, among others), is that nature has not yet adapted to take advantage of the changed environment. If we increase nitrogen in the air slightly, we expect life will evolve over time to be slightly more nitrogen-phillic somehow. Those gene-lines that manage this evolution survive, those that don’t die off. The problem of course for big slow species like large mammals, or trees, is that it takes a long time (many generations, hundreds, thousands, tens of thousands of years) to evolve in a way that is well-adapted to the new environment. So after a sudden change or shock, a species may find its way to a new equilibrium, assuming there are no other shocks or external changes to the system, or be beaten to its appropriate niche by some other species, and go extinct.
But life itself is a disequilibrating process. Humans (and a few other species) for instance invent “technologies” (from using sticks for digging, or rocks for breaking things, to fire or iPhones). These technologies change the environment for humans and other species. If we did that and stopped, an equilibrium could possibly be found. But we continue to invent.
Further, the earth itself is not a closed system. We are being continuously showered by radiation from the sun (you know, light and heat and all), (which we adapt to, assuming it is roughly constant). The earth is also periodically showered by the detritus of the universe (meteors and asteroids). These add to the disequilibrium we face, and are reputed to have done in the dinosaurs.
So it is one thing to say life will adapt to the changes in the environment humans create, undoubtedly some life will do better than others unless we manage to extinguish it all. The question is how long it takes to come to a steady state ( without any external shocks).
Should we privilege the “steady state” ante-Industrial Revolution vs some current or future “steady state”. That seems to me an entirely arbitrary preference. By restoring life to some elysian past we are condemning those species that evolved faster and co-evolved with our technology (from chickens and cows to pigeons and squirrels, among the larger life forms). To say this is the perfect end-state now diminishes possibilities yet to be.
What is our objective? Preservation of the existing mix of species, restoration of some past mixture, maximization of total biomass, maximization of human biomass? Unless people can agree on what it is we want to achieve, the means (pollute, don’t pollute) will remain unsolved. To say “Save the environment” begs the question of which “environment” we are trying to save.
However, if we think of this in property rights terms, we can either define the commons as unowned (which quickly degenerates to a bad outcome), or define it as owned by everyone, as if we are all shareholders in the commons, and the proxy is held by the government (or governments) (1).
In that case, individuals (and firms) have no inherent right to pollute (which we might define as measurably changing the chemical composition of the air (water, land) at some fixed distance, say 10m, at any rate some distance such that breathing does not count as pollution, but tailpipe emissions do). Instead of trying to geo-engineer an ideal world, which is beyond our abilities anyway, even if we could agree upon on it, we would regulate the inputs to that future world in the form of regulating pollution. Nature will then evolve to whatever it evolves to, with a minimal additional influence from humans. We might hope it turns out ok.
The transition from the present “environment as an unowned commons” into which we can dump anything to an “environment as communally owned property” into which we can dump nothing without permission or penalty will obviously be a difficult one. Many processes that were efficient in the absence of pollution prohibitions and penalties are inefficient in their presence. But crisis creates opportunity, and for every old-style industry and behavior the new regime obliterates, a new technology and way of operating arises.
This is the logical outcome of the <a href=”https://en.wikipedia.org/wiki/Enclosure”>enclosure movement</a>, which has been steadily assigning ownership to the unowned over the course of human history.
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(1) We could have an alternative, where the environment is somehow owned by selected individuals instead of as a commons or by nobody, but carving up the air is much harder than carving up the land, since air moves much faster than earth.
With recent neighborhood opposition to noise walls, an interesting question arises related to the effects of noise walls on air pollution. Do roadside barriers protect the neighbors from tail-pipe pollutants? Does this result in more pollution on the roadway itself?
The answer, as with everything is that it depends.
Baldaufa et al. (2008) in Impacts of noise barriers on near-road air quality (Atmospheric Environment Volume 42, Issue 32, October 2008, Pages 7502–7507) write in their abstract:
Numerous health studies conducted worldwide suggest an increase in the occurrence of adverse health effects for populations living, working, or going to school near large roadways. A study was designed to assess traffic emission impacts on air quality near a heavily traveled highway. The portion of highway studied included a section of open field and a section with a noise barrier adjacent to the road. In addition, the section containing the noise barrier included a portion with vegetation in the vicinity of the barrier. Thus, this field study provided an opportunity to evaluate near-road air quality with no barriers, with a noise barrier only, and with a noise barrier and vegetation adjacent to the road. Pollutants measured under these scenarios included carbon monoxide (CO) and particulate matter (PM).
Measurements showed the effects of a noise barrier on near-road air quality. The presence of this structure often led to pollutant concentration reductions behind the barrier during meteorological conditions with winds directionally from the road. CO and PM number concentrations generally decreased between 15 and 50% behind the barrier. However, conditions occurred when pollutant concentrations were greater behind the barrier than when no barrier was present. These results imply that the presence of a noise barrier can lead to higher pollutant concentrations on the road during certain wind conditions. In addition, the study results suggested that the presence of mature trees in addition to the barrier further lowered PM number concentrations.
Emphasis added
I talked before about things we can do to reduce the iciness of sidewalks. That is a supply side solution. We need to think about demand side solutions to the problem of ice-related falls on icy sidewalks.
Bill Lindeke wants to turn it into a game, but in the end, he is still young.
There are things we can do to better accommodate the ice as well.
I like the last one best. Why TF am I walking around on ice? In the end, not all travel can be safely accomodated.
P.S. The number of my falls each year can probably be measured by the number of posts complaining about ice.
Global Warming needs an advertising campaign. While those trying to stop it are well-funded, and many organizations try to deny it or minimize its effects, almost no one is selling us on its merits. Global warming opponents make is seem like the earth is going to become a dried up desert-like husk. One of my friends insists it’s too late, the Earth is Toast.
Embrace that idea. Instead of the “Earth is toast”, we need to say It’s Toasted, giving the new and improved earth a warm and cozy feel, like a hot breakfast on a Winter’s Day. And every day, we are slightly more and more toasted.
Brendon writes in:
Heating a sidewalk section has climate change implications. I calculate the 26-year cost of your section at $8,722 at the low end and $9,708 at the high end (depending on the discount rate you assign to the future impacts of climate change. I tend to lean towards the higher end). This means your break-even point is 8% to 20% higher, meaning maybe 173 to 192 pedestrians per day. Of course with a carbon tax in place, there would likely be more walkers in some places, meaning heating the sidewalks become feasible in more places.
Now, if you could use waste heat that hasn’t been previously captured to heat sidewalks, as they are proposing to do with the new “interchange” plaza and HERC steam, the carbon footprint becomes effectively zero additional. Much less per kWh/BTU.
Other interesting facts, heating all the sidewalks in Minneapolis with electricity from the grid for one year would produce more greenhouse gases than the disposal of all our solid waste and wastewater does over the same time period. The additional energy consumption would be equal to about 1/3 of the current annual consumption in all residential properties in the city. It would increase the city’s annual electricity consumption by 8%.
He nicely identifies a feedback effect, heating up sidewalks will create more emissions, which will heat the atmosphere, which will eventually negate the need for heating up sidewalks. There must be an equilibrium point here.
More seriously, the use of waste heat is a great idea, especially near the HERC. The problem would be building infrastructure to distribute that more broadly. There might also be waste heat from wastewater (which is still liquid in the winter, and thus warmer than the ground around it) which we don’t capture, or let go to roads, by running sewers under the streets rather than the sidewalks.
Volk et al (2012) Traffic-Related Air Pollution, Particulate Matter, and AutismAir Pollution, Particulate Matter, and Autism:
“Context Autism is a heterogeneous disorder with genetic and environmental factors likely contributing to its origins. Examination of hazardous pollutants has suggested the importance of air toxics in the etiology of autism, yet little research has examined its association with local levels of air pollution using residence-specific exposure assignments.
Objective To examine the relationship between traffic-related air pollution, air quality, and autism.
Design This population-based case-control study includes data obtained from children with autism and control children with typical development who were enrolled in the Childhood Autism Risks from Genetics and the Environment study in California. The mother’s address from the birth certificate and addresses reported from a residential history questionnaire were used to estimate exposure for each trimester of pregnancy and first year of life. Traffic-related air pollution was assigned to each location using a line-source air-quality dispersion model. Regional air pollutant measures were based on the Environmental Protection Agency’s Air Quality System data. Logistic regression models compared estimated and measured pollutant levels for children with autism and for control children with typical development.
Setting Case-control study from California.
Participants A total of 279 children with autism and a total of 245 control children with typical development.
Main Outcome Measures Crude and multivariable adjusted odds ratios (AORs) for autism.
Results Children with autism were more likely to live at residences that had the highest quartile of exposure to traffic-related air pollution, during gestation (AOR, 1.98 [95% CI, 1.20-3.31]) and during the first year of life (AOR, 3.10 [95% CI, 1.76-5.57]), compared with control children. Regional exposure measures of nitrogen dioxide and particulate matter less than 2.5 and 10 μm in diameter (PM2.5 and PM10) were also associated with autism during gestation (exposure to nitrogen dioxide: AOR, 1.81 [95% CI, 1.37-3.09]; exposure to PM2.5: AOR, 2.08 [95% CI, 1.93-2.25]; exposure to PM10: AOR, 2.17 [95% CI, 1.49-3.16) and during the first year of life (exposure to nitrogen dioxide: AOR, 2.06 [95% CI, 1.37-3.09]; exposure to PM2.5: AOR, 2.12 [95% CI, 1.45-3.10]; exposure to PM10: AOR, 2.14 [95% CI, 1.46-3.12]). All regional pollutant estimates were scaled to twice the standard deviation of the distribution for all pregnancy estimates.
Conclusions Exposure to traffic-related air pollution, nitrogen dioxide, PM2.5, and PM10 during pregnancy and during the first year of life was associated with autism. Further epidemiological and toxicological examinations of likely biological pathways will help determine whether these associations are causal.”
In general pollution has been going down in the US, and autism diagnosis has been going up. Some of that may be diagnosis issues (though the previously linked article suggests not). However, there is an interesting point, in the Volk article: “In addition, ultrafine particles (PM0.1) may penetrate cellular membranes.” As we filter larger and larger pollutants from the tailpipe, we may be making more small pollutants (One way to reduce measurable pollution particles is to make them smaller, so they are no longer measured). For instance the as wikipedia says about the Diesel Particulate Filter “maintenance free DPF break larger particles into smaller ones.”
David Levinson, Transportist 
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