Recently, we were called to test a Local Exhaust Ventilation (LEV) system used in the manufacture of seals for submersible suits. The process sounded simple enough — 1.5-metre-long rubber seals glued and joined in one continuous length — but the reality was a perfect example of why proper understanding of LEV use is critical.
The Setup
The operator was using a welding arm–style LEV to control airborne contaminants during the gluing process. The extraction point had a capture distance of around 220mm, and the adhesive’s Material Safety Data Sheet (MSDS) showed it contained toluene — a volatile organic compound known for causing dizziness, headaches, and long-term neurological effects with repeated exposure.
The gluing process involved applying adhesive, waiting for it to go tacky, and then sealing the length in one go. This meant the operator was exposed for extended periods while working close to the source of emission — exactly where concentration levels peak.
The Conversation That Said It All
When we spoke to the end user about how the LEV performed, his response was honest and eye-opening:
“It’s like a good Saturday night out when we’re gluing.”
That one line sums up one of the biggest challenges in occupational hygiene — human interaction and perception.
From a testing standpoint, the system passed: airflow readings were within specification, hood velocity was acceptable, and duct performance was fine.
But from a human standpoint, the system was failing in use. After full assessment, the LEV was recorded as an overall fail due to inadequate capture distance and ineffective control of exposure at the point of use.
Why End-User Understanding Matters
LEV systems don’t protect people just because they’re switched on — they protect people when they’re used correctly and understood by the operators.
It’s not enough to fit an extraction arm and tick a compliance box. If the operator doesn’t know where to position the hood, how far 220mm really is, or why fumes behave the way they do, the protection is lost.
Too many systems are designed, installed, and tested with no follow-through training — and as a result, operators normalize the smell, the dizziness, or the “buzz.”
That’s not compliance. That’s exposure disguised as normality.
The Real Lesson
This job reminded us that LEV testing is only half the picture.
The other half is conversation — understanding how the people who actually use the system think, work, and interact with it. Because when the human side is missing, even the best-engineered system becomes a false sense of security.