Smog is a form of air pollution that comes in 2 forms: sulfur and photochemical. Both of these pollution effects didnít become noticeable until the last 200 years. This is the most dangerous of all effects of air pollution to human health.
Smog is a word composed from a combination of the two words ďsmokeí and ďfog.Ē This is used to describe sulfur smog which started occurring in the 1800ís during the Industrial Revolution. In the Black Fog of London, 1852, thousands died of smog inhalation. The elderly or poor of health are affected the most. That was when coal was used for heating and smelting iron so the pollution built up in the cities, but since we have discovered new methods of keeping the sulfur emissions lower yet we still havenít eliminated them. The two ingredients in this smog, sulfur dioxide and water vapor, donít become extremely harmful until they chemically react and then bond together. This combination is sulfuric acid. Smog of this sort is like acid rain, it eats away and vegetation and can erode specific buildings and statues.
Photochemical is the more common and dangerous smog. It occurs mainly in the summer when sunlight is most plentiful. The ingredients needed for creation of smog are all found in car exhaust: nitrogen oxides, gasoline vapors, and carbon particles. These, combined with sunlight, create the O3 molecule or ground level ozone. It should be clear this isnít the world-saving ozone layer that protects us from the deadly UV rays the sun emits. Neither is it a version of the life giving substance we must breathe to survive. This is ground level ozone which causes a raw throat and watering eyes.
The three key requirements for photochemical smog are sunlight, stationary air, and heavy traffic. The substances for the smog come from cars, the energy for the reaction from the sun, but the stationary air is the key factor. Usually air circulates with the warmer surface air rising and the higher atmosphere air sinking. Sometimes the cold air gets trapped at the surface bellow a warm air blanket. This keeps the air from moving and pollutants just build up. This state of immobile air is called a temperature inversion.
The Catalytic converter was created to be our most effective means of fending off smog. Itís a device made of screens located in front of the muffler. The gases from the car are released through it and the pollutants are broken down into more purified forms. Nitrogen oxides are split into pure oxygen and nitrogen. Water vapors and carbon dioxide are released instead of carbon particles. In 28 states carsí catalytic converters are check at intervals to inspect for high levels of emission. If the converter does not pass it must be replaced. The catalytic converter is only 90% effective and so there are still 10% of harmful car emissions floating around waiting to become smog.