What causes the black dust in the London tube system?
Answers:
About half of the dust is iron. The proportion of asbestos is small and not dangerous; dangerous forms of asbestos were removed in the 80's. "The composition of tunnel dust reflects exactly what might be expected from the source of dust. The high iron content results from wear on the rims and flanges of the wheels and on the heads of the rails and by contact between the moving wheels and the track (HSE 1981). The quartz content comes mainly from wear on the brake blocks which, for the older blocks, contained significant proportions of quartz. Asbestos was at one time of concern because the brake blocks contained 5% white asbestos (considered the least hazardous of the asbestos types)." "Other sources of dust are the gradual wear of ballast, oily matter from lubricating systems, engineering work on the track and track bed and track reconditioning, wear on clothing and particles brought in by passengers and through the ventilation system."
Break dust from the trains
dirt, dust, rat droppings.
pouultion fumes dirt etc
Dust from the Brake pads on the trains.
The coal from the trains, oops i forgot we were in year 2006, sorry! Its the dust from the brakes, rats poop, mouse poop, bat poop. you get the idea?
Brake dust, human skin cells, rat poo, all sorts of things.
Definitely a 'wash your hands' situation if you get it on yours.
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