I went on a 3 day trip last weekend and you can see from the pictures in the photo linke below
how much particles collected in 3 days.
Lexus has authorized the dealer to change the a/c and heat exchange and have asked for samples
of the particles.
Lexus has been very quick to authorize whatever is need to fix this problem.
here is the link if you want to take a look at what I am talking about:
http://picasaweb.google.com/ccds22/RX350WhiteParticleProblem
just double click the thumbnails to enlarge the pictures