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Do coal and diesel trains make for unhealthy air?

A project funded by over 270 individuals via microryza.com

Project team:
Dan Jaffe, Sofya Malashanka, Greg Hof, Jeff Thayer and Justin Putz
University of Washington Bothell and University of Washington Seattle

APOLLO Research

Article with Research Findings Accepted for Publication, February 22, 2014

Atmospheric Pollution Research will be publishing the Apollo research team's article on the air quality implications of rail traffic in Washington State, "Diesel particulate matter emission factors and air quality implications from in–service rail in Washington State, US." The Apollo team measured particulate matter at two sites along rail lines, one in Seattle and one along the Columbia River Gorge. They found that living close to rail lines significantly increases one's exposure to particulate matter.

Here is the abstract from the article:


We sought to evaluate the air quality implications of rail traffic at two sites in Washington State. Our goals were to quantify the exposure to diesel particulate matter (DPM) and airborne coal dust from current trains for residents living near the rail lines and to measure the DPM and black carbon emission factors (EFs). We chose two sites in Washington State, one at a residence along the rail lines in the city of Seattle and one near the town of Lyle in the Columbia River Gorge (CRG). At each site, we made measurements of size-segregated particulate matter (PM1, PM2.5 and PM10), CO2 and meteorology, and used a motion-activated camera to capture video of each train for identification. We measured an average DPM EF of 0.94 g/kg diesel fuel, with an uncertainty of 20%, based on PM1 and CO2 measurements from more than 450 diesel trains. We found no significant difference in the average DPM EFs measured at the two sites. Open coal trains have a significantly higher concentration of particles greater than 1 µm diameter, likely coal dust. Measurements of black carbon (BC) at the CRG site show a strong correlation with PM1 and give an average BC/DPM ratio of 52% from diesel rail emissions. Our measurements of PM2.5 show that living very close to the rail lines significantly increases PM2.5 exposure. For the one month of measurements at the Seattle site, the average PM2.5 concentration was 6.8 µg/m3 higher near the rail lines compared to the average from several background locations. Because the excess PM2.5 exposure for residents living near the rail lines is likely to be linearly related to the diesel rail traffic density, a 50% increase in rail traffic may put these residents over the new U.S. National Ambient Air Quality Standards, an annual average of 12 µg/m3.

Read the full article here.

First Report to Supporters, November 4, 2013

First, thank you to all of the people who supported our project!

We worked hard to make our measurements and analyze the data as quickly as possible. The summary below is similar to the summary from the talk I gave at the University of Washington Bothell on November 4th, 2013. By now, you may have seen some of the media reports on the study. Here are the preliminary conclusions from our project. More details will be available in the final peer-reviewed scientific publication posted, which I will post here as soon as it is available.


Preliminary conclusions:
  • Living very close to the tracks in Blue Ridge neighborhood of Seattle increases one's exposure to Diesel Particulate Matter (DPM) by about 6.7 µgram/m3. This level of exposure is comparable to that in the most industrial parts of Seattle (Duwamish Valley).

  • We found a significant increase in large particles (>1 µm) in the air when coal trains passed as compared with other train types (passenger, freight, etc.). This result suggests that these trains are emitting coal dust into the atmosphere during transit.

  • An increase in train traffic will increase the DPM exposure for residents along the rail lines. A 50 percent increase in rail traffic will put some neighborhoods at risk of exceeding air quality standards.

  • We measured the DPM emission from over 450 trains to get a mean value of 0.94 grams diesel particulate per kg of fuel burned.

  • A publication describing this work has been submitted to a scientific journal and is currently in peer-review. The results presented today should be considered as preliminary until the final paper is available.

  • Our exposures (µg/m3) are based on one month of measurements at a home in Blue Ridge. At present, we do not know how the PM concentrations change as a function of distance to the rail lines.

  • Determining compliance with the EPA air quality standard requires a minimum of 3 years of data. Our one month of observations gives an indication of whether they may be a problem or not, but does not tell us about overall compliance.

  • Uncertainty on all values is +/- 30%.

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