Sanding, lots and lots of sanding.

Most "site vacs" should be at least M class because HSE has provided "guidance" that says this should be the case. However, more importantly is the standard of filtration and in this case HEPA is appropriate. It is possible to have vacs with good filtration (HEPA) that are not "M or H Class" but are still categorized as "HEPA" or "Type H - ATEX". To comply with the EU "class" bit the vacs have to have a warning light or sounder on that warns when airflow through the filter drops to below 20m/s (using the largest hose diameter the manufacturer supplies" and must pass various other tests which include blocked filter burst tests and picking up quantities of furniture tacks to make sure the filter doesn't get destroyed. If you think about it the 20m/s is pretty pointless once you start using different hose diameters, and if you stick a floor tool close to the floor the airflow goes down and the filter warning goes off! Warning of filter blockage through air speed is a c**p idea but there it is in the standard!

Generally, the difference between M and H Class is one of certification and testing/retesting rather than filter performance. There is a difference in the minimum standards but many manufacturers use the same filters in both M and H Class.

This is getting awfully close to my "day job".

one of these will do the trick

 

My wife has Asthma and the filtration is so good she has no problem with using the sanders herself. She quite often uses the CTL Midi as a regular household cleaner as it is much easier for her to use than a regular cleaner and the performance is much higher