Reply #1: you'd probably have a hard time finding some...

[Viva_La_Revolution]

As of December 31, 2003, the pressure treated wood industry discontinued the use of chromated copper arsenate (CCA) as the primary wood preservative used for most residential and general consumer construction. Existing CCA-treated stockpiles may be used until exhausted; however, the transition to CCA alternatives is well underway. There are several arsenic-free wood pressure treatment alternatives to CCA already on the market including ACQ, Borates, Copper Azole, Cyproconazole, and Propiconazole. There are also several alternative building materials to pressure treated wood that are available today.
http://www.epa.gov/oppad001/reregistration/cca/alternativestocca.htm

I do a lot of projects outside, and usually don't bother with the masks. If I was working inside I would though.