Phoenix Journal · LEV & Air Quality
Faced with a hazard, most workplaces reach for gloves and a mask. The hierarchy of control exists to stop that reflex, by insisting you work from the most effective solution down, not the most convenient one up.
Ask why a worker is wearing a respirator and, more often than not, the honest answer is that a mask was the quickest thing to hand. The hierarchy of control is the discipline that pushes back against exactly that instinct. It ranks the ways of controlling a hazard from most effective to least, and it asks a hard question at every level before you are allowed to drop to the next: could this hazard be removed, rather than merely endured?
The hierarchy has five rungs, worked from the top down. Elimination removes the hazard entirely, by designing out the process or the substance. Substitution swaps it for something less dangerous, such as a wet process instead of a dry one to stop dust becoming airborne. Engineering controls physically capture or contain the hazard, with local exhaust ventilation the classic example, taking contaminant away at source before it reaches anyone's breathing zone. Administrative controls change how people work, through procedures, training, rotation and limiting exposure time. And personal protective equipment, PPE, is the last line of defence, worn on the body when everything above has done all it reasonably can.
Why the order matters
The order is not arbitrary. The first three levels, elimination, substitution and engineering, control exposure without depending on human behaviour: once designed in, they work whether or not anyone remembers to do anything. The bottom two, administrative controls and PPE, rely on people following a rule or wearing equipment correctly every single time, and people are fallible, distracted and rushed. A respirator only protects the shift it is actually worn, fitted properly and maintained; an extraction hood protects every shift, whoever is standing at the bench. That reliability gap is the whole reason higher controls sit higher.
This is not just good practice, it is the law's logic. The Control of Substances Hazardous to Health Regulations 2002 build the same priority into Regulation 7: prevent exposure where you can, and where you cannot, adequately control it using measures in that order, with PPE as a last resort rather than a first reach. The burden falls on the employer to justify why a higher control was not used, which means a risk assessment whose only answer is gloves and masks is not just weaker than it could be, it is difficult to defend. For carcinogens and asthma-causing substances the expectation is stricter still, because there may be no safe level at all.
In a real workplace the levels are usually combined rather than chosen singly. You might substitute a lower-hazard material, capture what remains with LEV, limit how long anyone works at the task, and still issue RPE for the residual exposure. That is entirely correct; the hierarchy is about where the weight of protection sits, not about picking one rung and ignoring the rest. What it forbids is skipping straight to the bottom because it is cheaper or easier, and then calling the hazard controlled.
Where LEV earns its place
For airborne hazards, dust, fume, mist and vapour, the engineering rung is where most real control is won, and local exhaust ventilation is the workhorse that lives there. But LEV only counts as a control while it actually captures the contaminant at source, which is a design and maintenance question, not a purchase. The point is sharpest with welding, where managing welding fume means far more than buying extraction: the hood has to be in the right place, used correctly, and proven to work, or the engineering control that looked so reassuring on the risk assessment is quietly doing very little.
From principle to paperwork
The hierarchy of control is not an abstract pyramid to admire; it is the engine that should drive every real decision in a COSHH assessment. An assessment that names a hazard and then reaches straight for PPE has skipped the very reasoning the hierarchy exists to force. That is why doing the assessment properly matters so much, and why how COSHH assessments should actually be done comes back again and again to the same discipline: work down the levels honestly, justify each step, and make the controls real rather than aspirational. The hierarchy tells you what good looks like; the assessment is where you have to prove it.
Questions
From most to least effective: elimination, substitution, engineering controls such as local exhaust ventilation, administrative controls such as procedures and training, and personal protective equipment. The order matters because the higher levels control the hazard without relying on human behaviour, while the lower two depend on people acting correctly every time.
Because it only protects the individual wearing it, and only when it is selected correctly, fitted, used and maintained every time. It does nothing to reduce the hazard itself, and a single lapse leaves the worker exposed. Higher controls remove or capture the hazard for everyone, which is why COSHH treats PPE as a last line rather than a first choice.
The principle is built into UK law. The Control of Substances Hazardous to Health Regulations 2002 require employers to prevent exposure where reasonably practicable and otherwise to control it using measures in a set priority order, with PPE as a last resort. The employer must be able to justify why a higher-level control was not used.
Phoenix Duct Clean · by the numbers
LEV is only a control while it captures at source and passes its test. Phoenix supports LEV that is examined and proven, not just installed. UK-wide.