London's buzzing metro system, London Underground, has been seen to be polluted with particles that are both tiny and metallic. SciTechDaily reports how such particles are tiny enough to enter the human bloodstream. Given their minute size, such particles are likely underestimated in pollution surveys conducted on the oldest metro system in the world.
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Metallic and Ultrafine Particles Pollute London Underground
Researchers from the University of Cambridge saw these. Their findings can be seen in Scientific Reports.
As part of the study, the specialists conducted a further pollution analysis. They utilized magnetism to dig deeper into dust samples taken from the operator cabins, ticket halls, and platforms of the London Underground.
The researchers observed how their samples were filled with significant maghemite, a specific iron oxide. Because of the time it takes for iron to form maghemite, these findings suggest that pollution particles have long durations of suspension, because of ventilation poorness across the system, especially in the platforms.
Some of the observed particles have a diameter size that goes as small as five nanometers. This makes it tiny enough to be respiratorily ingested and end up within the bloodstream. At the same time, it is also too tiny to be captured by the usual pollution monitoring methodologies.
According to the Daily Mail, scientists are still unaware of the exact health risks that come along with such particles. Hassan Sheikh, the lead author from the same department, also notes that in answering the concern regarding possible health risks, it is first important to know the particles' composition and properties.
While previous studies have assessed pollution levels within the London Underground and the health risks linked to such levels, this is the first study that deeply analyzes the type and size of particles. The scientists suggest that periodically removing the dust from the tunnels and magnetically assessing pollution levels could boost the quality of air within the system.
Pollution in the London Underground
Daily Mail reports that over 5 million passengers board the London Underground each day. SciTechDaily also notes how several studies have revealed that levels of air pollution within the system are higher compared to London in general. Such levels also exceed the limits defined by the World Health Organization (WHO).
Richard Harrison, a professor from the Department of Earth Sciences at the university and the study's senior author, notes how because of the metallic nature of most air pollutants, the London Underground is an ideal testing place to see if magnetism can be an effective method of monitoring air pollution. Professor Harrison also notes how magnetism is usually used in studying planets. However, their team decided to see if such methods could be applied in different fields and areas, such as in air pollution.
The scientists also say that because of the poorly ventilated setup, dust rich in iron can be resuspended within the air as trains arrive. This worsens air quality in such areas compared to operator cabins or ticket halls.
Considering the magnetic nature of such dust, the researchers also suggest that an efficient removal system may include magnetic filters for ventilation, cleaning tunnel walls and tracks, or adding screen doors between the trains and platforms.
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