Since doing research on here I have switched from standard nozzles that come with a backpack to Teejet AI drift resistant nozzles. When I'm spraying round up I will smell the odor of the chemical. Is this JUST the odor or am I getting particles down in my lungs? I'm sure we've all had those times when a draft comes out of no where and you get a huge whiff of chemical. I always put my back to the wind (when there is a breeze) but the wind won't cooperate sometimes. When can you tell you are actually inhaling microscopic particles versus just the odor?