ABSTRACT
Particulate concentrations in Santiago during the winter months are among the highest for any urban area in the world, due to heat inversion and lack of wind in the valley basin where the city is located. A closed valley with little wind, little rain and thermal inversions during winter months contribute to worsening the impact of emissions. Climatic conditions differ significantly from those experienced in many capitals of tropical countries in the region where heavy rains in winter months, often windy summer months, and little possibility of severe heat inversions help to reduce relative concentrations, even under equal levels of emissions.
