Maintenance & systems
Extraction is a strong control, but it is not the only one, and not the first. COSHH sets a hierarchy - eliminate the substance, then substitute it, then engineer it out with measures like LEV, then safe systems, and only then RPE - and treating LEV as the whole answer skips the more reliable steps that sit above it.
The short answer
Extraction is a strong control, but it is not the only one, and not the first. COSHH sets a hierarchy - eliminate the substance, then substitute it, then engineer it out with measures like LEV, then safe systems, and only then RPE - and treating LEV as the whole answer skips the more reliable steps that sit above it.
The detail
COSHH Regulation 7 does not simply say 'fit extraction'. It requires exposure to be prevented where reasonably practicable, and only adequately controlled where prevention is not - and it sets out a hierarchy of control options ranked by how reliable they are. Elimination sits at the top, because a substance that is not present cannot harm anyone and there is nothing left to fail. Substitution comes next, swapping a hazardous substance or process for a less hazardous one.
Engineering controls, including LEV, sit below those. They are effective and they are the workhorse of most real workplaces, capturing contaminant at or near the source before it reaches the breathing zone - but they rank below elimination and substitution precisely because they rely on equipment that has to be designed, used and maintained correctly to keep working. A system that is switched off, mispositioned or unmaintained stops controlling anything, which is a failure mode that eliminating the substance simply does not have.
Below engineering controls come safe systems of work and administrative measures - job rotation, restricted access, procedures - and at the very bottom sits respiratory protective equipment. RPE is the last resort, not because it cannot protect, but because it protects one person at a time, depends on a seal on a face, and does nothing to control the hazard at source. Reaching for it first inverts the whole hierarchy and leans the workplace on its least reliable option.
The common mistake is to treat the hierarchy as a menu and pick the most convenient item, usually PPE, or to install LEV and consider the job done. Neither is what Regulation 7 asks. The duty is to work down from the top: can the substance be removed or replaced before extraction is even needed, and where LEV is used, is it backed by the safe systems and, where necessary, the RPE that cover what it cannot?
What it means for you
Seen properly, LEV is a powerful layer in a stack, not a standalone fix. The strongest control programmes ask the top questions first - can we eliminate or substitute - and only then design extraction for what genuinely remains, so the LEV is doing a defined job rather than papering over a hazard that could have been designed out entirely.
This matters when inspectors look at an assessment. A COSHH assessment that jumped straight to extraction, or straight to masks, without considering elimination or substitution is vulnerable to challenge on exactly that point - it skipped the more reliable controls. Showing that the hierarchy was worked through in order is part of demonstrating the exposure is adequately controlled.
None of this diminishes LEV. Where a substance must be present and a process must run, well-designed, well-maintained extraction is often the decisive control that keeps people safe. The point is simply that it is one step in a ranked set, backed above by prevention and below by safe systems and RPE - and that treating it as the entire answer leaves both better options unused and weaker ones carrying too much.
The service behind the guide
Questions
LEV is an engineering control. Under COSHH Regulation 7 it sits below eliminating and substituting the substance, and above safe systems of work and RPE, which is the last resort.
Because eliminating or substituting the substance is more reliable - there is nothing left to fail. LEV is effective but depends on equipment being designed, used and maintained correctly to keep controlling exposure.
No. RPE is the last resort in the hierarchy. It protects one person at a time and does not control the hazard at source, so it should back up engineering controls, not replace them.
Not necessarily. Regulation 7 requires working through the hierarchy. An assessment that fitted extraction without considering elimination or substitution can be challenged for skipping more reliable controls.
Very. Where a substance must be present, well-designed and maintained LEV is often the decisive control. The point is that it is one ranked layer, backed above by prevention and below by safe systems and RPE.
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