The 58 year old woman who supposedly nearly died had a history of health problems, and in the experiment, she had a minor complication that resolved within two hours. The original medical publication can be read here. This was published because no adverse health effect from breathing particulate matter had ever been observed before.
Despite the statement in the article at the top of this thread that "EPA has already determined that PM2.5 is lethal and can cause death within hours of breathing it..." there is, actually, no firm evidence of that. That determination was made on the basis of statistical analyses, in which a correlation has been found between high particulate content in the air and (very slight) increase in the number of asthma/COPD deaths. Since correlation is not causation, there actually is no solid evidence linking particulates to death. (I am not giving an opinion one way or the other here.)
Although, overall, I like Steve Milloy's work, I suspect that he is grandstanding with this lawsuit. It is not about supposedly dangerous research (which was conducted after IRB review, and with full consent of informed participants) so much as it is about scoring against the EPA. I'm not a fan of politically motivated lawsuits, no matter which side of the political spectrum is filing the lawsuit.
last September EPA Administrator Lisa Jackson told the Oversight and Investigations Subcommittee of the House Energy and Commerce Committee, “Particulate matter causes death. It doesn’t make you sick. It’s directly causal to dying sooner than you should.”
Now if that's actually true there could be no excuse for these human experiments, IMHO.
If it's not true in the way she allegedly stated it she flat out lied to the committee.