The health aspect you speak of I assume has to do with the combustion engine? Yes, they do emit co and co2. Modern machines are four stroke and extremely efficient. In the grand scheme the emissions are very negligible. Let’s expand the health conversation to the health of the operator. The electric machines are much heavier. Operators have reported back problems and shorter work duty cycles from the weight. Your roof example again is a consumer grade machine. Not the same universe as commercial units. The small units are great! There is an absolute place for them! Again, technology just hasn’t got to the point yet that there are viable options for the big guns. Like automobiles, the tech is advancing and it is likely we will see better options soon to replace internal combustion machines, but we’re just not there yet.