Trains And Air Pollution: What's The Connection?

Trains create air pollution, but the extent of their impact depends on various factors, including location, the type of fuel used, and the level of exposure. While diesel trains emit pollutants like particulate matter (PM) and nitrogen oxides, electric trains are much cleaner and produce significantly less greenhouse gas emissions per passenger kilometre. In recent years, there has been a growing awareness of the air pollution caused by trains and a push for decarbonization, particularly in California, where rules have been passed to fund cleaner locomotives and reduce rail idling near residential areas.

Locomotive exhaust contains pollutants like particulate matter (PM) and nitrogen oxides

PM2.5, or fine particulate matter, is composed of particles with a diameter of 2.5 microns or less. These particles can penetrate deep into the lungs and enter the bloodstream, causing cardiovascular and respiratory issues, including lung cancer. Short-term exposures to PM2.5 have been linked to premature mortality and various health issues, making it the pollutant with the greatest proportion of adverse health effects related to air pollution in the United States and worldwide.

Nitrogen oxides (NOx) contribute to smog formation, creating a lethal form of air pollution. Smog has been directly linked to heart, lung, and cardiovascular disease, as well as asthma. Locomotive emissions of nitrogen oxides are particularly concerning in areas with high freight traffic, such as the Los Angeles basin.

While rail is one of the lowest-impact public transport methods in terms of carbon footprint, the impact of locomotive exhaust on air quality and public health cannot be overlooked. The pollution from freight trains is poisoning millions of people, and the rail industry has been criticized for remanufacturing old locomotives instead of transitioning to cleaner, zero-emission alternatives. Efforts to reduce locomotive emissions, such as California's recent rule to fund cleaner locomotives, are crucial steps towards improving air quality and protecting public health.

Rail companies remanufacture old, polluting locomotives, keeping them running for decades

Rail companies regularly remanufacture old, polluting locomotives, keeping them running for decades. This practice has severe health consequences for communities, particularly those near rail yards, who are exposed to toxic diesel exhaust and pollution. Locomotives typically run on diesel engines that emit nitrogen oxides and particulate matter, which are harmful to human health and can even cause premature death. The problem is exacerbated by the fact that emissions regulations are only implemented when a locomotive is newly constructed, rebuilt, or overhauled, allowing locomotives to go years without any upgrades.

The EPA has been criticised for not updating locomotive pollution rules in over 15 years, with standards based on outdated technology. While there have been advancements in battery electric locomotives, the introduction of Tier 4 locomotives, which meet the highest emission standards, has been slow. Rail companies have taken advantage of a regulatory loophole that allows them to remanufacture locomotives to Tier 2 or lower standards, rather than meeting the latest Tier 4 standards. This has resulted in a fleet of "'zombie trains", some of which date back to the last century, that continue to pollute communities with outdated and inefficient technology.

The negative health impacts of locomotive pollution are well-documented. An EPA study from 2014 found that communities near Chicago's Cicero rail yard experienced elevated air pollution when winds blew emissions towards residential areas. Similarly, a 2018 study in California examined 18 freight rail yards and found that children living within five miles of a rail yard had a significantly increased risk of asthma-related emergencies. These health risks disproportionately affect lower-income residents and residents of colour, who are overrepresented in neighbourhoods near rail yards.

In response to growing concerns and demands for change, states like California have taken the initiative to address the issue. California's Air Resources Board has passed rules to fund cleaner, zero-emission locomotives, reduce rail idling near homes and schools, and phase out old, remanufactured locomotives. These rules are expected to significantly reduce nitrogen oxide (NOx) pollution and greenhouse gas emissions, saving lives and reducing the risk of cancer and other health issues. However, the rail industry has pushed back against these regulations, suing California to block their implementation.

It is clear that the remanufacturing of old, polluting locomotives by rail companies has contributed to air pollution and posed significant health risks to nearby communities. While some states are taking action, there is a need for nationwide regulations that prioritise the health and well-being of those affected by locomotive pollution.

Air quality at train stations is often poor due to fumes, restricted airflow, station design, and train component wear

Air quality at train stations is often poor due to a combination of factors, including fumes, restricted airflow, station design, and train component wear. These factors contribute to the generation of harmful pollutants that can have negative impacts on the health of passengers, workers, and nearby residents.

Fumes released from diesel engines are a significant contributor to poor air quality at train stations. Diesel exhaust contains particulate matter (PM), which consists of tiny airborne particles that can burrow deep into the lungs. These fine particles have been classified as carcinogenic by the World Health Organization, posing risks of lung cancer and other respiratory issues. Additionally, diesel engines emit nitrogen oxides, which are a key component in the formation of smog, directly linked to cardiovascular and respiratory diseases.

Restricted airflow and inadequate ventilation in enclosed railway stations exacerbate the problem. The confined nature of these spaces allows pollutants to accumulate, increasing the concentration of harmful substances. Station design plays a crucial role, as certain layouts may hinder proper airflow and ventilation, leading to higher pollution levels.

The wear and tear of train components, such as brakes, wheels, and electrification systems, also contribute to air pollution. The friction between wheel and rail, for example, generates metal-rich ultrafine particles that can be inhaled, potentially causing respiratory issues. Additionally, the age of the train fleet is a factor, with older locomotives often being more polluting due to outdated technology and inefficient fuel systems.

Furthermore, the high frequency of train movements and long idling times can intensify the pollution levels at train stations. Optimizing schedules, reducing idling, and improving engine technologies can help mitigate these issues. Additionally, the adoption of alternative fuels, such as biodiesel and renewable diesel, can significantly reduce greenhouse gas emissions and improve air quality.

It is important to address these issues through a combination of technological advancements, policy interventions, and improved station management. By prioritizing air quality in train stations, we can minimize the health risks associated with poor airflow and create a safer environment for commuters, workers, and nearby communities.

Electric trains produce much less air pollution than diesel trains

Trains do cause air pollution, but the type of train makes a big difference. Electric trains produce much less air pollution than diesel trains.

Diesel trains emit pollutants such as particulate matter (PM) and nitrogen oxides, which have been linked to heart, lung, and cardiovascular disease and asthma. In contrast, electric trains have zero emissions at the point of use, which is particularly beneficial for air quality in pollution hotspots like city centres and mainline stations.

The benefits of electric trains over diesel trains become even more apparent when comparing their carbon emissions. Electric trains typically emit between 20% and 35% less carbon per passenger mile than diesel trains. This advantage will only grow as the electricity generation industry continues to reduce its carbon levels. For example, the UK's decarbonization of the national grid, which involves removing fossil fuel power stations in favour of low and zero-carbon alternatives, will further decrease the carbon intensity of electric trains.

The UK has recognized the benefits of electric trains and is investing £4.2 billion in railway electrification projects across England and Wales. These projects include creating a high-capacity "electric spine" and electrifying additional lines, which will reduce carbon emissions and fares. Similarly, California is at the forefront of the fight against train pollution, with the Air Resources Board recently passing rules to fund cleaner, zero-emission locomotives and cut down on rail idling near homes and schools.

While electric trains are a more environmentally friendly option than diesel trains, it is important to note that the rail industry is complex, and other factors can impact the overall carbon footprint. For example, the manufacturing and maintenance of electric trains, as well as the energy sources used to power them, can vary in sustainability. Nonetheless, electric trains offer a promising solution to reducing air pollution and improving air quality, especially in highly populated areas.

Transport hub buildings, including railway stations, are susceptible to poor air quality

The health impacts of air pollution on train commuters vary depending on location, the type of fuel used, and the extent of exposure to polluted air in enclosed and underground stations. While the impact on train commuters is generally lower than for those who commute by car, the concentration of particulate matter (PM) inside trains can sometimes exceed the WHO's 24-hour indoor guideline. These emissions include tiny airborne particles that can cause illness and disease, affecting passengers, workers, and nearby residents. Locomotive exhaust contains pollutants like PM, which can burrow deep into the lungs, and nitrogen oxides, which create a lethal form of air pollution called smog linked to heart, lung, and cardiovascular disease, as well as asthma.

To address this issue, rail operators can implement train-side interventions such as using cleaner fuels, more efficient engines, and filtering systems, as well as transitioning from diesel to electric trains. Electric trains produce around 20-30% less greenhouse gas emissions per passenger kilometre. They are also lighter, more efficient, and cheaper to maintain and run than diesel trains. Station-side solutions include improving ventilation and airflow within stations, exhaust fans, station design modifications, and real-time monitoring of air quality.

Some regions have already taken steps to improve air quality in transport hubs. The South Australian government has retrofitted trains with electric traction modules and energy-storage systems, resulting in significant fuel and emissions reductions. Additionally, California's Air Resources Board has passed rules to fund cleaner, zero-emission locomotives, reduce rail idling near residential areas, and phase out old, polluting locomotives. These efforts demonstrate a recognition of the health and environmental consequences of poor air quality in transport hub buildings and a commitment to finding solutions.

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