This is a transcript of John Snawder's personal experience and observations at the hydraulic fracturing sites visited by NIOSH and for which worker exposure levels are described in the NIOSH hydraulic fracturing site reports of 2010/2011 and by the resulting journal article, Essweing et al., 2013. The basis for this transcript was a telephone conversation between John Snawder of NIOSH and Whitney Long and John Eyraud of ERG, May 29, 2014.  
If you've seen the JOEH paper, and seen the actual company reports, then you'll know the exposures are very job related. The blender has a cab on it. The worker in blender often times would have door open or window open, so often it is not a controlled environment. Depending upon the placement of people and specific wind and weather conditions, the cabs almost can become a collector, and workers might get higher exposures to silica inside the cab. Operators of sand movers, which usually have open controls, open to the environment, can work on the ground or higher up, but there are no cabs in any case. Usually they have some sort of respiratory protection. It might not be full face, but at least half mask or filtering face mask. [Sand delivery] Truckers are only there 10 to 30 minutes. They tended to be in and out of their truck, usually somewhat upwind of the operation; its not like they stayed in their truck. Other workers don't like to have truckers sitting in truck, they tended to be in and out of truck. For Hydro unit operators (no cab) and water trucks (truck cab), there was less of an exposure issue. Chemical techs would have a cab, but it's usually doors/windows open. So the cab issue mainly concerns blender operator. 

Folks working in the control trailer, they were always inside, with tempered air. Both the manager and the technicians in here, from which a lot of site activity is controlled remotely. The guys who are controlling and monitoring pumps, they are instructing other workers on site by radio. The Site manager would be there, including the chief or head technician for a given operation that day. 

The wireline crews, if they are perforating along with the frac, usually are not in a cab but usually are set back away from that work. They are in their trailer, loading perf guns. This is not a booth per se but usually they are off doing job. When they are around, there is no pumping or blowing sand. 

Truckers, it is not so much they plan to be upwind, sometimes they aren't, but typically, it is just the way the pad is arranged. They are coming to outside perimeter to offload, primarily staying out of the high concentration zone. 

For workers who are in the cabs, it is most common that it [the cab] is open to the air, [during the NIOSH fracking site visits of 2010/2011 this investigator] rarely saw blender operators with the cab closed. They need to see, they have swing out type windows, and the windshield on the cab and that will be rocked out forward, to see what is going on in the blender without looking through a dirty window. 

Only 5 or 6 guys of all the workers, during well stimulation, are in the dusty area. These are the workers who had the elevated exposures during the NIOSH site visits. Workers who area already often spending most of the shift enclosed (e.g., in the control trailer) are not the ones who had the elevated exposures measured during NIOSHs visits to fracking sites.

Do we need a better cab? Often times the [blender] operator cab, not the vehicle cab, have some better design, such as where it is angled on front to face the hopper itself, also better to have the door in the back, so then upwind side takes the brunt of the exposure. 

In the JOEH [i.e., Esswein et al, 2011] paper and others, you'll see the blenders were second highest exposure group. We saw some operators using equipment with cabs, but seldom saw operators using them as enclosed cabs (operators typically did not keep cab doors or windows closed). 

Would use of enclosed cabs help reduce exposure?  Yes, shutting doors, A/C in cabs, [air] filtering in cabs would help a lot.

Would a video system work [to improve visibility]? Is remote operation possible? Industry has talked about this. They currently control the pump centrally (from the site control trailer); it is partly tradition the way it is arranged now. The truck could be controllable remotely too. People do need to make sure sand is blowing and not clogging. Not possible to have people inside 100% of the time. 

He has not seen refuge cabs or any special system for cabs [at these sites]. He has seen no new approaches to doghouses. Although it is pretty darn high tech, as far as tech side, but is the box super-upgraded? No. 
Some cabs have larger picture window, some don't. Looking right now at frac equipment for sale, might still see some that don't have cabs at all, not all are computer controlled, not electronic. 
 
On front page of a brochure, the blender on their cover does not have a cab (The Stuart Stevenson fracturing/blender page) and they don't have a cab. But scrolling down, have some really good models. 

Typically the person who owns, the operator runs all and everybody else is a contractor. 
Might be a big oil or big gas company. Workers earn a Special SafeLand card, SafeRig (offshore) card. It is pretty much an industry wide standard. The first orientation, it is about an 8 and 10 OSHA training. Lot of voc tech colleges offer classes. Some unions do it. For Entry level workers, usually the operator for a given site, they will have their safety, EHP, all workers have to then have taken operator's EHP, 4 or 5 hours. They check your helmet for a sticker when you are on  site. Each of the contractors have own training. When on a site, it is complicated when multiple jobs occurring, usually have site meeting. Lots of JSA of different companies. They describe hazards and answer questions at opening daily meeting. The concern is high consequence, low frequency events. Considering the tasks they do, really amazing industry safety record they have. You can't pick up 400 lbs 1,000 times per day and not get some reportable events. 

