In addition. It is not just the extractor that needs testing (as indicated in the article) It is also the ducting system as they generally leak like a sive and are part of the extraction system, especially if you use primarly MDF or other more hazardous woods.
Well frankly anyone stupid enough to ignore an Improvement Notice from a HSE inspector deserves everything they get. I suspect the £10K-ish it cost them in fines and costs is peanuts compared to the kind of wonga it would cost in compensation for a worker who contracts pulmonary disease as a result of shoddy practices re dust.
Before anyone on here with a home workshop (most of us I suspect) panics, it's probably worth re-stating for those who don't already know, that HSE regs are only of consequence to businesses. The HSE gets its teeth from the "Health and Safety at Work Act" - if you're not "at work" you are free to poison yourself till the cows come home