What are the main findings of the study?

Our main finding is that air pollution from outdoor tobacco smoke can be quite high near active smokers. The average levels can be comparable to those measured _indoors_ when people smoke. When one is within a few feet of an outdoor smoker and downwind, the levels are highest. An important finding was that a person near an outdoor smoker could breathe in wisps of smoke that could be 10s or 100s of times more concentrated than normal background air pollution levels.