Finding hidden pollution on the tube.
Pollution on the London Underground may be more harmful than previously thought, but the solution may be pure magnetism.
Summary: Researchers from Cambridge University have found a method for measuring previously hard to detect pollution particles using magnetism. Previous studies had found that concentrations of particulate matter (as small as one twentieth the width of a human hair) on the London Underground are higher than those in London more broadly (above ground). However, those studies may have even been underestimating overall pollution levels given that some of the smallest particles have been historically hard to measure. Those tiniest particles are so small you would need 7,000 of them piled on top of each other to equal the width of a human hair! The researchers conclude that removing dust from the underground periodically, and using magnetic monitoring, could provide a cost effective strategy for reducing exposure.
Why this is important: Even in an increasingly remote-working friendly environment, public transportation will remain an important component and the health of workers and impact on productivity remains a key risk and concern for all.
The big theme: Achieving acceptable air quality has various significant investment and decision-making considerations. The most obvious are the implications on human health from a purely altruistic point of view. Decreasing pollution with the aim of decreasing human illness and suffering is (should be) a goal unto itself. In practice however, the focus is primarily on how such initiatives (that more often than not increase costs and dig into profits), will be beneficial to business in the long run, whether it be through decreased healthcare costs, increased health and productivity of the workforce, and reputational gains for such decisions.
The details
Summary of a story from the University of Cambridge:
Previous studies in London and Seoul have concluded that most of the particulate matter on the Underground is created as wheels, tracks and brakes grind against each other and very small metallic particles are thrown up. Given that they are metallic researchers from Cambridge University suspected that they could use magnetism to identify and monitor those particles which are often too small to be caught by standard air filters and even then are not individually identified.
Combining disciplines from the Department of Earth Sciences and the Department of Materials Science and Metallurgy, the team led by Hassan Sheikh and Professor Richard Harrison used high-resolution electron microscopy and electron tomography (think of it as '3D magnetic fingerprinting') to analyse dust samples collected from the London Underground across a number of different lines from ticket halls, platforms and train driver cabins. This enabled them to identify the structure of the different particles that made up the dust. They found that there was a large amount of maghemite particles (a type of iron oxide) with an average diameter of only 10 nanometres. Theses individual particles were found to often form larger clusters of up to two micrometres or microns meaning that traditional monitors were overestimating the average 'particle size.'
