Thanks for this.
Agreed about the impact compared to big industry....but I was just thinking to myself at the sheer number of weld and fab shops, factories, training centres and thought 'Wow, I bet they add up'.
So am I right in thinking that it is only the particulates that get filtered, as it is not possible to filter out the fume such as Ozone, Carbon Monoxide, etc, etc.
Particulate filtration is pretty easy generally, as it can be captured fairly well, HEPA etc. It's any gaseous or molecular contaminants that are difficult and or expensive. That said there now exist all sorts of specialist filtration units within the HVAC industry to treat the most common contaminants. Remember that LEV isn't just associated to welding, it's a diverse requirement aand basically any process that has dust, fumes, or noxious by-products dangerous to health are covered. COSHH guidelines give far more detail than I can here, however from our perspective welding is probably the one we're concerned with, but in essence it affects many other industries, pharmacutical etc...
Carbon filters, electrostatic, chemical filters / scrubbers, ozone filters, UV etc etc etc. Theres a good selection of means of dealing with the by products, it's the sort of thing thats very complicated pretty quickly, however it's alwaays the case of is it needed to comply? no, then unlikely to be done. However, you're right the quantity of fumes can accumulate quickly, espeially in industrial areas / zones, but again, more so for the larger industries. I'm not aware of any specific requirement to treat discharged welding fumes specifically after Local capture etc, plenty of requirements for the treatment / filtration internally, but none for the treatment of the discharge to atmosphere (maybe something @Parm could comment on?) I've been out of the uk for way too long now to be up to date on the latest regs, the chartered institude (CIBSE) would probably be a good starting point for research information, .