Just anecdotal. It's always said that living in Los Angeles is like smoking a pack a day. I suppose when you add the strenuous exercise on a bike and the extra respiration, you double it.
However, Darwin or other such areas might not prove much of a solution. There may be particulate pollution in some of those areas, red dust, or desert areas sand.
I think there was some study or concern here at Owens Lake as the dust storms there were considered the worst air in the state.
dc