I was a bit horrified when I watched the documentary and heard the very idea of testing exhaust on primates or humans to prove a point about diesel NOx not being harmful to breath... Or at least that's what I assume was their aim.
Then I had to stop and think for a second. Oh wait. I breath that in all day every day. And particulates, because I still fix mostly older TDIs that predate DPFs! ****, maybe they should just do studies on technicians, they have a big enough pool of them in their dealer network. Speaking from experience, they run cars indoors all the time and breath the fumes!
Then I went back and remembered some reading I did. One was even from the EPA on the subject of NOx. Another a separate article about the breakdown of diesel NOx into individual components and their amounts... NO, NO2, NO3 etc. Apparently, the vast majority of diesel exhaust is just plain old NO. NO is pretty harmless. Hell, if your body isn't naturally producing NO in your veins via your endothelial cells, you get plaque clogging your veins eventually causing a serious health crisis.
The amount of really harmful NO2 and other forms of NOx is very minimal in diesel exhaust. The only problem is when NO is lingering in the right atmospheric conditions, it can combine with VOCs/NMOGs (which come from gas engines in much larger quantities than diesels) in the local air and do a chemical reaction with sunlight and low winds, relatively high ambient temperatures (conditions often present in many areas of California) and cycle into O3 and NO2 among other unhealthy forms of NOx.
So, looking at it that way, realistically no harm would have actually been done to the test subjects, despite the slightly inaccurate portrayal (c'mon, they even used a gasser Ford on the dyno and a mk4 Beetle, which never came with a "clean diesel").
Also, I hear today that California is now going to sue places that sell coffee for not having Prop 65 signs. For those unaware, Prop 65 warnings basically just say the facility you're entering contains chemicals known to the state of California to cause cancer... Which is basically everything at this point, according to the state.
Some days I wish I could replace all those signs with more accurate wording: "WARNING: The number one cause of death is being alive!"
And if you still think forcing primates to breath diesel exhaust is bad, maybe you should be nicer to the person turning wrenches on your car because he does it all day every day and still soldiers on. Bring him/her a beer or something. I hear alcohol does wonders for flushing NOx out of your system