Posted By Adrian Daniels We have around a dozen closed test chambers that we run vehicles in (diesel and petrol). In these chambers there are fixed exhaust extraction and other sources of ventilation. We have also got systems for gas detection in place but I am currently reviewing them with a view to introducing a new system / systems. I would like to get a feel for what other companies are doing with this issue. The debate I am having is between installing a fixed system (expensive) versus a handheld/portable approach (cheap, but with more emphasis on people using it!) Any information would be greatly appreciated. Thanks