I guess you will have to review what the inspector is asking for compared to what you have now.

Do the suggestions for improvements really improve safety/exposure to hazardous substances by operators or are they just 'nice to have' improvements?

This has been said before but most LEV inspections just test the level of “suck” produced by the LEV based on some standard (but essentially arbitrary) set of criteria. What you need to be looking at is how and if the LEV is providing you with the level of operator protection you require for that particular job. Something like a smoke testing is a good indicator of this. It is perfectly possible that a 30 year old system is giving you exactly what you need and a brand new system could be completely wrong for what you want even though the level of airflow at the face is what some standard says it should be: it’s just the wrong standard for what you need.

I always worry when a new contractor turns up to do an inspection and suddenly old equipment which is performing well "needs to be replaced or you need to do a lot of work to bring it up to standard to comply with new or updated legislation".  The question I will always ask of them is how do you know and explain to me why and under what legislation.  Especially if they also try provide the replacement/upgrade work.  I have come across a number of companys over the years who will try and gain work following an inspection by bending or omitting parts of legislation.  My message is dig deep into inspection reports and ask questions of the people who have proved it. Then if necessary go out for quotes.

As a qualified Statutory Inspector off LEV systems I survey Older systems all the time.

Note without knowing what was picked up or recommended it is difficult to make an informed judgement against recommendations in this case so the following is a suggestion for guidance only.

Firstly do you have the original Design Specification for the LEV System and can you produce it for comparison.

If you have and the Flow, Capture, Velocity and Static Pressure readings achieved in the survey are comparative with the  original design specification initial test results or are better and the capture has been deemed sufficient using smoke as a verification then there should not be any main issues.

If no design is available, then the flow rates as mentioned in HSG 258 should at least be met and if so then the system should pass.

Most recommendations raised for older systems are normally around Flow indication not being provided for the system which in the new HSG is a recommendation and the removal of so called (Chinese Hats) from the top of the vent stacks which are for weather protection and are no longer allowed.

These should be replace with something suitable such as a Jet Cowles for Weather protection.  The former type impedes the flow of contaminant from the system and causes back pressure.

Secondly has the process being carried out or substance used changed since the LEV was designed and installed, or has it been modified in any particular way which now prevents or reduces the  capture rate.

Additionally is the method of capture being applied now the most suitable way of controlling the contaminant e.g. is it being drawn away from the face of the operator and not across their face to enter the system. Or would an enclosure, Down Draft or Back Draft bench be better suited to the process as opposed to a canopy over the system. I hope this helps.