Out with bad air, in with the good - Usually what we’ve done in situations like these is to try and provide fresh air to the operator’s station/ breathing zone - including sometimes air conditioning if the guy is in a hard sided little cab enclosed, or a little flex duct and a fan system maybe combined with a screen (even a little three sided “cab” or screen like a snow blower) so the worker’s breathing zone is a little more “enclosed” or separated from the general environment and the supplied fresh air goes into his breathing zone. Watch the velocity you supply the air at so you don’t excessively cool the face or upper body too. Further down the choice list perhaps are fresh air hoods/ helmet types of things that supply low pressure air over the front of the face from the top. When exhaust bugs the operator, he just plugs in the hose , dons the helmet and turns on the fan - there’s no face seal or anything, just air at reasonable volume and ambient pressure (you can even heat or cool this air but that’s getting fancy). With both these types of setups you always have to watch were you get the fresh air from - that it stays fresh - and that somebody doesn’t park idling equipment right beside the air pickup!
May seem like a weird reminder but . . . if the engine is diesel, the emissions might contain carbon monoxide, but more to the point they contain small particulates (carcinogens) and oxides of nitrogen (NOx), the latter which are very irritating to lungs if levels are high enough for a long enough time. Why this is important is that NOx (and SOx) are both pulmonary irritants known to be capable of causing pulmonary oedema (edema in the US) - fluid accumulation in the lungs. Someone can feel ill, go home and lay down and fall asleep and not wake up again due to fluid building up. I was part of a fatality investigation years ago where a summer student who was a non-declared asthmatic fell ill at work after working in an area where diesel exhaust (and other things) were present, he went home and his parents found him passed away that evening from pulmonary oedema. It happens. At the least, it could be like operating equipment while slightly impaired, again depending on pollutant levels, and tree work is the type of job where you want everybody sharp and wide awake (CO from smoking doesn’t help either). Hope that helps a bit. Stay safe ’n sound everybody.
