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Study finds coal trains add significant amount of PM2.5 pollution in urban areas

Coal trains and terminal operations add a significant amount of fine particulate matter (PM2.5) pollution to urban areas—more so than other freight or passenger trains—according to a study conducted in Richmond, California, by the University of California, Davis.

The open-access paper, published in the journal Air Quality, Atmosphere & Health, is the first study of coal train particulate pollution in a US urban area. It’s also the first to use artificial intelligence technologies to verify that the source of air pollution detected comes from coal.

Coal Levin terminal_drone (c) Michael Layefsky

A shipment of coal awaits loading at the Levin-Richmond marine terminal shipyard in California. (Michael Layefsky) In 2020, the Richmond City Council passed an ordinance banning the handling and storage of coal and petcoke within the city by January 2023. The move prompted lawsuits in federal and state courts from three companies and Utah, all of which argued it was unconstitutional. A settlement reached in 2021 keeps the law in place but gives the companies to 2027 to comply.

We developed a novel artificial intelligence-driven monitoring system to quantify average and maximum PM2.5 concentrations of full and empty (unloaded) coal trains compared to freight and passenger trains. The monitor was close to the train tracks in Richmond, California, a city with a racially diverse population of 115,000 and high rates of asthma and heart disease.

We used multiple linear regression models controlling for diurnal patterns and meteorology. The results indicate coal trains add on average 8.32 µg/m3 (95% CI = 6.37, 10.28; p < 0.01) to ambient PM2.5, while sensitivity analysis produced midpoints ranging from 5 to 12 µg/m3.

Coal trains contributed 2 to 3 µg/m3 more of PM2.5 than freight trains, and 7 µg/m3 more under calm wind conditions, suggesting our study underestimates emissions and subsequent concentrations of coal train dust. Empty coal cars tended to add 2 µg/m3.

Regarding peak concentrations of PM2.5, our models suggest an increase of 17.4 µg/m3 (95% CI = 6.2, 28.5; p < 0.01) from coal trains, about 3 µg/m3 more than freight trains. Given rail shipment of coal occurs globally, including in populous areas, it is likely to have adverse effects on health and environmental justice.

—Ostro et al.

The authors released a full report last week to the California Air Resources Board (CARB) with additional measurements of coal and petroleum coke (a byproduct of oil refining). It demonstrated that the storage and handling of these materials at shipping terminals and train holding yards also emit PM2.5, and that this air pollution reaches residential communities.

That report further describes the health and environmental justice implications of coal-related pollution for residents in Richmond and in nearby Oakland, where a coal terminal proposal is currently under discussion.

Rail conveyance of coal accounts for one-third of US rail freight tonnage and is a source of fine particulate matter, which is associated with a range of health problems, from heart and respiratory disease to premature death and adverse birth outcomes. But the contribution of air pollution from coal trains has been difficult to quantify, given difficulties in monitoring and discerning coal-carrying trains from other trains.

For this study, UC Davis air quality researcher Nicholas Spada developed an artificial intelligence-driven monitoring system to quantify the average and maximum PM2.5 concentrations of full and empty coal trains compared to freight and passenger trains. The device can differentiate between coal, freight and passenger trains, day or night, and measure the fine particulate pollution they produce in real time.

The researchers said an unforeseen benefit was that this technology can be applied to help pinpoint the source and level of pollution of many air pollution concerns, from refinery flaring and construction dust to unloading and loading at shipyards.

The World Health Organization and US Environmental Protection Agency indicate there is no known safe level of PM2.5. A recent study of the Global Burden of Disease estimates that fine particulate matter pollution contributes to 6.7 million deaths per year globally.

The scientists did not measure ultrafine or coarse particles (PM10), which are also generated with PM2.5. This indicates that the study likely underestimates the actual health risks posed by passing coal trains.

The study was funded by the California Air Resources Board Community Air Monitoring Grant Program.


  • Cite this article Ostro, B., Spada, N. & Kuiper, H. (2023) “The impact of coal trains on PM2.5 in the San Francisco Bay area.” Air Qual Atmos Health doi: 10.1007/s11869-023-01333-0



Interesting but it is generally known that you have to cover cargo!
Only neither the skippers nor the truck drivers close the cargo with a tarpaulin or a lid and thereby pollute the airways of people and animals and the entire air of the earth illegally but tolerated by politics and ecos! Why am I not the only one asking? In Europe and Germany, where I still live, this pollution from DUST is particularly bad because the trucks, agricultural machinery and ships mostly drive in the area of villages and cities! Complaints to German authorities are always dismissed because they understand that the trucks and ships are ecological. Well, the lives of people and animals are less valuable in Europe and Germany than cheap trucks and agricultural machinery tours with dusty dirt through the villages!
Yes, in Gemany this is an agricultural license for environmental pollution as there are no emissions regulations!
You now know that the dusty dirt is not only a problem when transporting coal by rail, but all journeys with dusty goods such as sand, straw, hay, earth, gravel, dirt from building demolition and much more!

Do you remember "S.L.A.G" from a TV series from the 80s?

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