We discussed Acid rain in our previous article. Let’s continue the discussion further and take up smog this time.
Smoke refers to the minute carbon particles that are formed as a result of incomplete combustion and fog is the dispersion of liquid particles which remain suspended in atmosphere near the earth’s surface. Smog simply put, is a mixture of smoke and fog.
Smog can be of the following two types-
Sulphurous smog- It is formed due to the presence of SO2 which may be due to the release of burning of coal. There is no photochemical process involved here. It can blanket urban areas at night or on cold days when the atmospheric conditions are relatively calm. A very famous example is that of London smog of 1952. This smog killed approximately 12,000 people and sparked a debate about environmental pollution. In the aftermath, the clean air act was passed.
It can cause diseases like asthma, bronchitis, pneumonia etc.
Photochemical smog- NOx preset in the atmosphere which may be released due to the automobile exhausts causes another type of smog formation that is known as photochemical smog (Los Angeles Smog). High vehicular density areas are more prone and it occurs when vertical air movement is a bit restricted. It consists of No2, PAN (Peroxy acetyl nitrate), Hydrocarbons, CO and Ozone. It can cause irritation, damage to vegetation and also reduce visibility.
PAN (CH3COOONO2) is one of the constituents of photochemical smog. It causes eye irritation. Also known as oxidising smoke and has brown fumes which can cause damage to the eye and lungs.