Although U.S. coal consumption has declined significantly since 2005, the country still consumes millions of tons of it annually and exports tons more, much of it transported by train. Now, new research shows that those trains can affect the health of people living near them.
The study found that residents living near railroad tracks likely had higher rates of premature death due to air pollutants released when coal trains pass over the tracks. Analysis of the San Francisco Bay Area cities of Oakland, Richmond and Berkeley shows that increases in air pollutants such as particulate matter (PM 2.5) are also associated with increased asthma episodes and hospitalizations.
“This phenomenon has never been studied anywhere in the world. There have been a few studies trying to measure just air pollution, usually in rural areas, but this was the first to measure both air pollution and trains in an urban environment,” said Bart Ostro, study author and an epidemiologist at the University of California, Davis.
Persistent coal pollution
Trains carry nearly 70% of U.S. coal shipments, leaving a trail of pollution behind them. And coal exports will have a similar impact during transport. Ostro explained that when uncovered coal trains travel, coal particles spread around the tracks. PM 2.5 levels “(spread) nearly a mile away,” he added.
As a result, the mere passing of coal trains could affect the health of surrounding communities. Ostro was particularly concerned about how these pollutants could harm vulnerable populations living near the Richmond coal export terminal. Previous census data had already shown that Richmond residents living near the rail line had mortality rates 10 to 50 percent higher than the county average. Communities in Oakland could also be at risk, as discussions are underway to build a new coal export terminal in the area.
But before they could study the health effects of these air pollutants, the researchers first had to determine how much of the pollutants were being released when the trains passed through. That was a challenge because coal trains aren’t scheduled like regular passenger trains.
To ensure that the researchers could measure all the trains and pollutants, Ostro and his team developed a monitoring system with three main components: a weather station to provide weather parameters, an air quality sensor to track air pollution levels, and an AI-trained camera to recognize coal trains. The trained cameras were essential to the entire project, identifying different types of trains: full coal trains, empty coal trains, freight trains, and passenger trains.
Using this system, Ostro’s team measured pollution levels and was able to attribute them directly to coal trains. Their results, published last year, showed that coal trains and terminal operations added a significant amount of PM 2.5 pollution to urban areas, more than other freight or passenger trains. Passing coal trains added an average of eight μg/m3 to ambient pollution. This is two to three micrograms more than what freight trains produce. Even empty coal cars contribute to increased pollution levels due to traces of coal dust.
Particle problems
This year, in a follow-up study, the researchers combined these findings with data from the U.S. Census and health surveys to understand how this increase might affect local communities. They estimated that more than 260,000 people would be exposed to an annual increase in PM 2.5 concentrations, and that this exposure was associated with significant mortality and morbidity.
Health effects were quantified for three different scenarios based on different wind conditions. In the worst case, where an increase of about two μg/m is observed3 In the vicinity of the railway line, modelling suggests that premature mortality would increase by 1.3%. Hospital admissions for conditions such as chronic lung disease, pneumonia and cardiovascular disease would also increase by 4.7%, 6.2% and 2.2% respectively. While these figures are relatively small in a small population, Ostro points out that they could be extrapolated to larger populations in other countries.
“I think this is a microcosm of what could happen globally,” he added. While coal use – and its transportation – is down in the United States and the European Union, the same is not happening everywhere. In countries like China and India, for example, coal use is increasing and people living near the railways that transport that coal could be at risk.
“These findings have major implications beyond San Francisco and the United States,” said Michel Abramson of Monash University in Australia, who was not involved in the study. He said Ostro’s assessment “fills an important gap” by examining the health effects of transporting coal in uncovered rail cars, but he doesn’t think there are any solutions to mitigate the problem other than stopping coal use.
“Covering coal cars may not solve the problem, as it could increase the risk of fire,” he added. “Ultimately, the world needs to phase out the mining, transportation and burning of coal, not only to reduce the risks of climate change, but also to improve people’s health.”
Environmental Research, 2024. DOI: 10.1016/j.envres.2024.118787
Bárbara Pinho is a science journalist specializing in climate, health and agriculture, based in Porto, Portugal. For more of her work, visit barbarapinho.com or follow her on X (formerly Twitter) @BarbPinho
