Definition - What does Smog mean?
Smog is a type of air pollutant. The major cause of smog is vehicle emissions, but it is also caused by the burning of coal and by photochemical reactions. Smog can be hazardous to the human body because it contains ozone. Ozone is colorless, odorless gas made up of three atoms of oxygen. The ozone in smog is found in the lower atmosphere, near ground level.
Safeopedia explains Smog
The ozone in smog can irritate the respiratory system. This can lead to coughing, throat irritation and and an uncomfortable feeling in the chest. Lung function can also be impaired, making it difficult for a person to breathe as deeply as they normally would. This may make breathing feel uncomfortable. Smog can aggravate asthma and it can also damage and inflame the lining of the lungs.