I've always wanted to try this.
Did you have a friend controlling the shutter release?
Is it possible to do this solo? Also, did you have to wear a mask?
There were a few photographers there and 2 of us doing the action
The camera is on a Shutter release and as its dark, it can stay open as long as you want
No mask for the wire wool, BUT I would advise taking all safety measures you see fit, all is needed is Wire Wool, a Whisk (to put the wire wool inside and spin) a cable of some sorts to attatch whisk with wire wool in to and some WD40 to give it a little bit of combustion/go (The WD40 isnt always needed it just helps)
For the light I had a mate hiding behind a pillar and then came out spinning it after I finished with the wool
Can it be done solo, sure, in a dark place like the underpass we did it, just takes a bit longer, obviously wear as dark clothes as you can so you dont come out on the exposure