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.