The study estimated how much future pollution levels would be reduced by corrective measures that would either (1) reduce vehicle emissions by reducing vehicle age, reducing the sulfur content of diesel fuel, and replacing half of two-stroke mopeds with four-stroke mopeds, (2) reduce the total vehicle kms required for a given number of trips by using buses for heavily traveled routes. Each of these approaches would reduce pollution by about the same amount, but neither alone would reduce pollution to an acceptable level.