Dying to Get to Work


As New York State sets up a commission to study the costs and benefits of New York City’s congestion pricing proposal, a new study by the Clean Air Task Force finds that, for many New Yorkers, the greatest exposure to dangerous and unhealthy air pollution comes during the daily commute. "Although we spend only about six percent of our day commuting to and
from work, it is during that time when we receive over half of our
exposure" to diesel exhaust, researchers found.

CATF is a nonprofit organization dedicated to restoring the environment through scientific research, public education, and legal advocacy. They are responsible for research at New York University that linked asthma rates in the Bronx to traffic pollution.

This more recent study investigates the levels of diesel particles during commutes in several cities (Austin, Boston, Columbus and New York City). CATF measured pollutant levels during commutes by car, transit bus, commuter train, ferry, and while walking. One surprise among the findings is that pollution levels measured inside cars, buses and trains were many time greater that levels in the air outside at the same time.

The report makes several recommendations like banning the use of diesel in underground tunnels and installing catalyzed diesel particulate filters which can reduce exhaust by 90%. New York City’s diesel-electric hybrid buses were singled out as a possible solution because their exhaust levels were barely detectable.

The report found that even short exposures to these harmful pollutants have a wide range of serious health effects. Only a few hours of breathing diesel particles may lead to:

  • Irritation of nose and eyes, respiratory/lung function changes, cough, headache, fatigue and nausea.
  • Pulmonary inflammation found after one hour of exposure to diesel exhaust.
  • Increased risk of pulmonary inflammation to asthmatics after two hours of exposure.
  • Adverse cardiovascular effects. Changes in heart rate variability, heartbeat and blood indices were recorded in North Carolina Highway troopers exposed to elevated in-vehicle particulate matter during midnight to 9 AM shifts.
  • Doubled risk of death due to stroke. Risk increased by a factor greater than two within two hours of exposure to high levels of fine particles in a Japanese study.
  • Suppressed defense mechanisms and increased susceptibility to lung bacterial infection for a week after exposure. Rats exposed to diesel exhaust for four hours per day for five days experienced prolonged growth of bacteria in the lung during exposure.
  • Larry Littlefield

    One thing for sure — the diesel engine, more than the rubber tires and almost as much as the lack of an exclusive right of way, is the reason that when buses replaced streetcars transit became the transport mode of losers.

    Prior the RTS buses that came on line in the 1980s I couldn’t even ride one without feeling sick.

  • Jason, I don’t think anyone “takes it lightly when Bloomberg mentions asthma.” What is worth examining critically, however, is the assumption that the congestion pricing proposal will make a noticeable dent in asthma rates. Intuitively, I don’t believe it will. Has anyone presented a convincing analysis on this score? My sense is that asthma reduction is far far down on the long list of impressive benefits from the proposal. — CK

  • anon

    I love the Bush straw man “some skeptics”- nice work. Traffic will be worse in the Bronx, where ppl will drive and try and park to avoid the congestion zone. Its a red herring and a straw man all in one paragraph.

  • This is a very good report on some very interesting work; thank you.

    I think CK’s point is well taken. There is no reason I have seen to think that congestion pricing will affect diesel soot emissions. Therefore, the claim that cp will cut asthma rates has always seemed under supported at best to me. To the moderate degree soot emissions are associated with asthma, significant tail-pipe controls and decreases in diesel miles driven could have some impact, but congestion pricing?

  • Most of the exposure comes from not from diesel particles in the ambient environment but from diesel particles in the vehicle itself:

    “pollution levels measured inside cars, buses and trains were many time greater that levels in the air outside at the same time.”

    The study doesn’t say whether pollution levels inside cars are greater than inside trains, so we don’t know if congestion pricing will reduce exposure by shifting commuters from cars to trains. (But I don’t know if they are even talking about subway trains.)

    But it does seem to say that pollution levels in hybrid buses are much lower, so we will presumably reduce exposure if congestion pricing shift commuters from cars to hybrid buses:

    “New York City’s diesel-electric hybrid buses were singled out as a possible solution because their exhaust levels were barely detectable.”

    Presumably, that affects the level of pollution inside the bus as well, but we really need more information about this.

  • Angus Grieve-Smith

    I can’t believe they’re talking about diesel levels inside subway trains. The only diesel trains in the subway are the work trains, and they’re pretty rare. Oh, and boy do they smell!

    Similarly for commuter trains, diesels aren’t allowed in the tunnels in NYC. The only terminals within a few miles of Manhattan that have diesel trains are Hoboken, Newark, LIC/Hunterspoint and Jamaica. The LIRR runs some dual-mode diesel-electric locomotives; it’d be interesting to know how long the diesel particles linger after the locomotives switch to all-electric operation.

    Anon 3:07, it’d be nice if you and the other people predicting that “ppl will drive and try and park to avoid the congestion zone” actually had some evidence that that would happen. Something to counter all the evidence that shows that no, people generally don’t do anything like that.

  • Angus Grieve-Smith

    Ah, from the FAQ:

    Q: People are exposed to high pollution levels traveling on commuter trains and
    buses. Does this mean that mass transit is a dangerous way to commute?

    A. No. In fact, electrified subways and light rail were the cleanest modes of

    This is a good argument for (re-)electrifying the remaining diesel rail lines in the area, like the Erie Main Line in New Jersey and the LIRR in eastern Long Island.

  • Steve

    There is only a single passing reference in the report to a London study that found that levels of bicycle were elevated along with pedestrian and passenger auto expsoure. I wonder how bicycling stacks up to motorist or pedestrian exposure.

  • mfs

    Angus- I think the diesel in tunnels recommendation refers to vehicular tunnels, not subway tunnels.

  • Angus Grieve-Smith

    Makes sense to me. I feel bad for all the people who commute through those tunnels every day.

  • Charles and anon,

    We had edited and rewritten the beginning of this article. Unfortunately, the changes didn’t stick due to work that we were doing on our publishing system on Friday morning. An older, unedited version of the article was published accidentally.


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