Santiago Chile is the captial and largest city in Chile. Located in the center of the vast country, it’s also known for it’s smog.
Thermal inversion (a meteorological phenomenon whereby a stable layer of warm air holds down colder air close to the ground) causes high levels of smog and air pollution to be trapped and concentrate within the Central Valley during winter months. In the 1990s air pollution fell by about one-third, but there has been little progress since 2000. – Wikipedia