The inversion effect is a phenomenon that keeps smog at ground level due to layers of air having different temperatures. This happens mostly in polluted metropolises during the dry season. It is predominant in Bombay, and other Indian cities, as well as Los Angeles, California.

This phenomenon sees the smog getting entrapped in a cool air layer that prevents the pollutants from rising above ground level. The pollutants in the air form a brownish haze that can cause respiratory problems. The effect is more pronounced when there is a lack of wind and humidity.

See also: Temperature inversion