I have come across something i have not seen previous so thought i would put t to the hive mind for comments.

I have been at a company that produce stone/quartz worktops. Their main cutting equipment is an enclosed CNC controlled cutting saw which uses a direct water feed to control the duts - it's very effective. However, they also do hand finishing and polishing of the worktops before delivery, and the chap doing so uses a small hand-held polishing disc, and sprays water onto the worktop from a small water pipe which has a diffuser fitted to produce a cone of water about 6 inches across, in order to control any dust produced durng the polishing.

The user was not wearing a mask - nor any goggles - although in his partial defence the water hose was held pointing away from him all the time (although it doesnt stop him inhaling any aerosol droplets).

Although the water is cold - below 20c - I still have a concern that he is breathing in the mist and the water will warm up when it gets into his lungs.

An FFP3 mask will not protect againt aerosol water mist so is there something that will protect him, short of a full head resprator with an air feed? I ask because his manager had the usual issue about getting the chap (who is a 'mature' worker) to actually wear a mask for the whole working day. The company pride themselves on their hand-made products so this finishing is a key part of what they do so they won't replace it with a mechanised alternative (and they probably can't afford such equipment anyway)

Any thoughts?

Oxford

If the water is from a mains supply at less than 20 degrees C, I would doubt that legionella is a problem even if it were decanted into containers for subsequent use.

In theory if you had one legionella bacterium per litre of water, then I suppose this could multiply in the lungs. Whether this might produce sufficient bacteria before being exhaled or otherwise processed by the lungs to produce sufficient dose to create a measurable risk is one for the experts.

But, this has been one of the recommended ways of suppressing silica dust in the process you describe for at least two decades and this is the first time I have ever heard mention of legionella as a possible risk to be dealt with.

Edited by user 15 May 2021 17:52:04(UTC)  | Reason: Corrected typo

I take it this dust control system is operated on a weekly, if not daily, basis meaning the water is not stagnating at the end of a dead leg.

Given standard legionella controls include weekly flushing of dead legs I would suggest there is no need for RPE in this circumstance, at least not for the purpose suggested in your post.