Well while we're discussing the theoretical adverse effects of NOx, I can contribute in that in cases of large quantities of exposure, one of the more immediate fatal consequences is known as "odema of the lungs" This occurs when the body recognises that the interior lining of the lungs has been damaged and the lungs start to produce large quantities of fluids in an attempt to repair the damage. The problem is, this is extremely similar to drowning..fluid in the lungs in both cases and you wake up dead. Twice in my underground career (35 years ago) I coughed up large quantities of blood due to excessive exposure to blasting fumes which contain, EXTREMELY large percentages of NOx. WE always know when its present because it gives the blast smoke a very characteristic red colour. I probably inhaled more NOx on those two occassions than 10,000 people in Los Angeles would inhale in their collective lifetimes. If I die tomorrow, its not likely to be due to NOx exposure. This issue REALLY is blown out of proportion by the tree huggers.