Nick,

From what I can tell, the nanoparticles of biodiesel are somewhat different in character from regular diesel, but are still present. What is absent is not the carbon particles, but the contaminants of sulfur and other potential contaminants. But that is just from a very simple search. I found one reference paper to biodiesel that may be helpful (follow the link on the word "biodiesel").

Apparently Seong Chan Kim has done some interesting research on respirators and nonoparticles too:

http://www.me.umn.edu/~schankim/E16A...44A078969.html

http://www.me.umn.edu/~schankim/6397...54F19B6CB.html

Also, I just found this new book on the NIOSH Nanoparticle website, titled:

Respiratory Diseases Research at NIOSH

Reviews of Research Programs of the National Institute for Occupational Safety and Health

http://books.nap.edu/openbook.php?re...=12171&page=R1

Use the search engine in this on-line book, and you will find a lot of references to diesel. It is the carbon in diesel which is of concern on the nonoparticle scale.

I have talked to researchers on nonoparticles from NIOSH at a conference two years ago, and they were saying that new research, perhaps that done by Dr. Kim above, had shown that nanoparticles such as diesel exhaust (carbon content) was effectively filtered by HEPA filtration on cartridge respirators, and N95 masks too. Probably the EU FFP1 would also do the job, but there needs to be a very good fit on the mask, and if it is the disposable EU FFP1 or USA N95 masks, they need to have both straps in place and the mask fitted well around the face to ensure a seal.

John