It's "risk assessment" again. The old equation of how long the workers are exposed to the dust, how toxic is the dust, how much dust accumulates over a given period of time, etc etc.Then why are the machines just in open space ? no extractors are present and no filtration system is in sight if as you say it's safe by who's standards ?
there is simply no way the airbourne dust is removed efficently other than by means of circulation and through the open doors etc .
If there were real concerns from royal fail to protect it's 'people' then they would have an extraction system above every machine in the mail centres as a precautionary measure this proves they care more about cost than the health of it's 'people'
There was a London office (now gone) where they insisted on blowing the machinery once a week, and if the rumours were to be believed, it took an employee's suspension to finally stop this mushroom cloud being released into the atmosphere.
It's worth bearing in mind that "our" machines are German, French, American and Japanese, and are installed similarly in the "home" countries, so any failing wouldn't be attributable to RM anyway.