[Bill S (OP)]

The 10 monkeys were placed in sealed chambers in front of TVs showing them cartoons, as Volkswagen Beetles drove on a treadmill, and their diesel fumes were pumped into the breathing spaces…..

But over the weekend, the German newspaper Sueddeutsche Zeitung unearthed further reports indicating that nitrogen dioxide tests were carried out in humans around the same time.

Volkswagen’s Emissions will Lead to 1,200 Premature Deaths in Europe

[Bored chemist]

It depends (among other things) on whether or not the humans volunteered.

[Bill S (OP)]

It depends (among other things) on whether or not the humans volunteered.

Chances are they did, and were paid, but I'll bet the monkeys didn't volunteer. 
Nor, I suspect, did the people who may suffer as a result of exposure in public places.

[alancalverd]

Bizarre. The concentration limits for chronic and acute exposure to nitrogen and carbon oxides are set down in law, and the composition of exhaust gases can be measured very accurately. What on earth were they trying to show?

[evan_au]

Apparently, as a young man, Sir Humphrey Davey shut himself in his laboratory gas chamber, and told his assistant to keep pouring in Nitrous Oxide until he passed out.

This was a lot more successful (and pleasant) than a previous episode where he tried inhaling carbon monoxide....