Err... Are you aware that the PCV valve (when properly functioning)
prevents backfiring from igniting crankcase fumes?

Not to mention that your whole logic on this is equally flawed. If
you're really concerned, simply run the PCV hose to the air filter
housing, and connect it via a filter like most older american V8
engines used. That way you retain the positive benefits of the PCV
valve, and filter out any of the airborne contaminants you are so
concerned about.

Read paragraph 6 he
http://autorepair.about.com/od/maint...maintain_2.htm

See second last item he
http://www.ramairbox.com/accessories.html