the geographical source of your air is not only important, but also the altitude it is collected at as trace elements like ozone increase at higher altitudes. and it is the trace elements that can give you the edge over other riders in harsh conditions. here are the approximate percentages at sea level:
Carbon monoxide 0.00001%
Ozone (O3) 0 to 7×10−6%
Nitrogen dioxide 0.000002%
you'll pay a fortune for aftermarket trace element fortified air at the motorbike shops (although cheaper if bought online through the USA).
but some cheap do-it-yourself tricks including pissing in your tube for extra ammonia, farting for methane, supermarket salt for iodine, and stuffing bits of old supeman magazines in for krypton.
it's true you can break up headlight bulbs for xenon but it's hard to get it in the tube. and of course one of the benefits of global warming is the extra carbon content we can expect over the next few decades.
free enduro training vids for gumbies here