Feeling sick sounds like co related (or bad pie for your dinner lol...) the cough and bad chest sound like the mold /alge water mist related to me.
All the H&S related info on co poisioning refers to useing a petrol engine inside or in partly sheltered areas, EG car parks, barns etc.
as you will never achieve the critical levels of co air mix outside it's not really considered a problem. (The phrase urinating in the ocean springs to mind) You could turn the machine round so as to point the exhaust outlet away from the work area.
100 feet of hose is 33 metres thats 3 and a bit 10 metre lenghts, seems a bit ott to me if your machine is outside and on wheels. I do use up to 10 lenghts but my machine is in a truck mount situation, most jobs I get away with 3 or 4.
I suffer from a smokers cough and I don't smoke (filthy habit) I can taste mould when I cough, its particulary bad at the moment cos of a couple of big well moldy/mossy jobs Iv'e done will try post a pic later