Thailand has tried for years to deal with its pollution problem. One big reason is the burning of corn stubble to clear fields for the next planting, a time of year from February to April that's known as “haze season.” And it gives Chiang Mai, a top tourist destination in the north, some of the world's worst air pollution during those months. One idea for tackling the smoke is requiring people to register to burn their fields. Researchers developed an app that uses weather and satellite data to predict if a fire on a particular day will cause more pollution or whether conditions will blow away the smoke and pollutants.