When Guido challenged Sadiq Khan over the toxic levels of particulates in the air on the London Underground, a spokesperson for the Mayor of London said:

“Londoners deserve to breathe clean air wherever they are. That’s why the Mayor is taking action to improve air quality both above and underground and within central and outer London. For too long not enough was done to tackle Tube dust. But since 2016 under the Mayor’s direction, TfL has enhanced tunnel cleaning practices to reduce Tube dust, increasing the amount spent by over 30%. By doing this Tube dust has already been reduced by around 20% when measured at the platform and nearly 40% when measured from the driver’s cab. TfL monitoring has shown that dust levels on the Tube remain well below the limits set by the Health and Safety Executive (HSE).”

Guido understands that plans made in 2011 by Mayor Boris for a new tunnel-cleaning train to hoover up potentially harmful dust on the London Underground network hit the buffers in 2017 under Mayor Khan. The project was cancelled supposedly because of “technical difficulties”.

Sadiq’s spokesperson also claimed “Tube dust is predominantly made up of iron oxide. Iron oxide is not currently known to be a carcinogen or have other significant health impacts.” This is not true, and it is well-known that airborne iron oxide particulate matter is a danger to human health.

The term particulate matter 2.5 (PM2.5), refers to tiny particles that are two and half microns or less in width. PM2.5 is an air pollutant that is a concern for Londoner’s health when levels in the air of tiny particles are elevated. The current legal limit for PM2.5 in the UK is currently set at 20 μg/m3, the World Health Organisation limit is set at half that 10 μg/m3. London Underground levels are way over the safe limit.

According to the US government’s National Center for Biotechnology Information, iron-rich air pollution nanoparticles are an environmental risk factor for myocardial mitochondrial dysfunction and cardiac oxidative stress:

Exposure to particulate air pollution is a major environmental risk factor for cardiovascular mortality and morbidity… Both acute and chronic cardiovascular impacts have so far been attributed to particulate-mediated oxidative stress in the lung and/or via ‘secondary’ pathways, including endothelial dysfunction, and inflammation. However, increasing evidence indicates the translocation of inhaled nanoparticles to major organs via the circulation. … Of potential major concern is the abundant presence of iron-rich air pollution nanoparticles, emitted from a range of industry and traffic-related sources. Bioreactive iron can catalyse formation of damaging reactive oxygen species, leading to oxidative stress and cell damage or death.

High-angle annular dark-field scanning/transmission electron microscopy (HAADF-STEM) of left heart ventricle tissue, 3 year-old (A–C) and 26 year-old (D–F)

The research concludes “acute and chronic exposures specifically to iron-rich airborne nanoparticles, which are abundant in the urban environment, constitute a plausible, pervasive risk factor for cardiac mitochondrial dysfunction and subsequent Cardiovascular Disease development, from earliest childhood”.  Sadiq says it is safe, scientists say it increases heart attack risks even in children…