There are an awful lot of variables here. What’s the capacity of your local exhaust ventilation system, its location to the affected area and whether the dust is dry or humid, what are they using as grit, does the dust settle readily or does it stay suspended, you say the area is open to the atmosphere, is it just an open area or do you have a good air “flow” through the affected area. I have come across this before and we ended up with an enclosure around the gritting site with direct local dust extraction from with in this enclosure (it was just a small mobile scaffold tower and sheeting worked great but you do have to allow adequate air flow into the set up) creating negative air pressure with in the enclosure stopped the dust from leaving other than via the extraction system.

The short answer is "No, LEV will not be effective". See http://www.hse.gov.uk/pubns/priced/hsg258.pdf From para. 146 - "Capturing hoods will nearly always be ineffective when placed more than a hood diameter away from the source." Regards, Ross

We have a situation at the moment were contractors have sand blasted metal frame work on the exterior of our building and are in the process of respraying it for fire integrity. They have used a system called "Envirowrap" however we have had Dust penetrate the building, and even though the windows are kept closed and sealed with masking tape, we are also getting a very strong fume penetration? From what I have read from the above threads and from the HSE book, it seems to me that the contractors are either using a very bad LEV system, or none at all, I am having a teleconference this coming Friday with our ESS team and the contractor and would appreciate any further evidence that I am correct in what I am assuming is correct, any thoughts would be greatly appreciated.