Smog

Smoke + fog = smog, originally used to designate the mixture of natural fog and Waste Gases (from Power Stations, domestic fuel, Motor Vehicles, etc.), and which is today used generally to designate heavy air pollution. A distinction is drawn between two types of smog: London smog, which is formed especially during the cold part of the year, and Los Angeles smog (Photo-chemical Smog), which forms under the influence of strong sunlight. Smog, of no matter what type, has considerable adverse effects on the environment and on health.