First, I spotted Anna's post about a Swedish study entitled, "Cardiovascular fitness is associated with cognition in young adulthood." Then, I saw a link to an article (I can't remember where) about a study that showed the negative effects of gasoline fumes on the brains of rats. The Wired article I read says that researcher Amal Kinawy of Cairo University found exposure to gasoline fumes made rats more aggressive and anxious. Moreover, some of the changes in the brain are described as "damage."
“Rats exposed to unleaded gasoline showed indications of increased damage caused by free radicals and altered levels of neurotransmitters in the brain cortex region, in comparison with the control or leaded-gasoline groups. Furthermore, inhalation of both fuels induced significant fluctuations in neurotransmitters in the hypothalamus, hippocampus and cerebellum.”Brain damage?! The health benefits of cycling just reached a whole new level. Perhaps, in the interest of public health, the CDC should revive the "Is your trip necessary?" posters from WWII. Of course, they would need to change the imagery to suit the times--one person sitting in a huge SUV amongst a smoggy sea of other solitary drivers in SUV's ought to do it.