Originally Posted by: Bazzer 
I have a client who sprays multiple products onto wood. All are solvent based, and from the SDS have very similar health effects. Since the hazards, first aid and control measures are basically the same would it be acceptable to roll them all into one COSHH assessment (listing the products).
A couple of products are isocyanate based so will have a separate COSHH assessment for these. Is it standard practice to wear air-fed RPE when using isocyanate based lacquers even when sprayed in a spray booth with LEV, or would a half mask with suitable filters be acceptable. I assume health surveillance is also required.
If the practice is to use multiple chemical mixtures on wood, the COSHH should address the
process rather than separate for individual components. However! If the components are used separately as well, there would need to be COSHH assessments for each process.
COSHH assessments are, after all, a risk assessment of the process and the controls of those substances which are hazardous.
As for LEV vs filtration mask, you want to refer to ERICP (or whatever acronym is now used).
E = eliminate. Can you stop the process? Probably not.
R = reduce. Can you use less of the chemical? Can you use a less harmful chemical? Reduce the time of exposure? Potentially, but probably not.
I = isolate. Can this be done in an area where fewer people may be exposed? Quite possibly.
C = control. Can we control the exposure? YES engineering controls including LEV and/or spray booth fall firmly into this category.
P = PPE (or RPE). YES, we can issue masks, but LEV has come before this so should be explored further first.
Of course, this is going to be done so far as is reasonably practicable, and typically masks are cheaper but bear in mind you'll need your SSOW to address the use of LEV/RPE, your risk assessment/COSHH assessment to highlight the amount of exposure and, as you allude to, health surveillance for controlling something that should protect lung function. It's also worth bearing in mind you would need a thorough inspection every <14 months for the LEV, some flow monitor to prove it works when it should, and in the case of masks, correct fitting for the type of mask(s) used.
Apologies if this comes across condescending in places; not my intention. Just thought it more worthwhile to spell it all out in case someone else visits with a similar query.