What is smog?
Drive by any large city in the world and you will see it. Sometimes it looks like a big gray or brown cloud hanging in the air. It's called haze or smog or ground level ozone, and it's a genuine health problem for millions of people around the world.
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Much of the smog problem today is what is known as photochemical smog. Basically, the term refers to a complex chemical reaction whereby sunlight breaks down chemical compounds such as volatile organic compounds (VOCs) and nitrogen oxides (NOX) into their constituent parts. Once broken down, the now free oxygen molecules can link up with the oxygen in the air (O2) and create ozone, which is a variation of oxygen, with one additional oxygen molecule attached to it. Hence, the chemical name of ozone is O3.
Both VOCs and NOx occur naturally, and can contribute to ground level ozone problems. However, anthropogenic (human initiated) sources remain the focal point of policy analysis.
Volatile Organic Compounds (VOCs) represent a group of chemical compounds that share some common characteristics. First, the organic designation means that the compound is almost always composed of carbon (C) and hydrogen (H) molecules. Volatile means the compound is easily evaporated. A quick reflective moment on the evaporative nature of two primary problematic VOCs in terms of ground level ozone, gas and oil, brings to mind the evaporative quality of the property. You can not fill up you gas tank without noticing the odor.
The major man-made source of VOC emissions is motor vehicles. Evaporation of gasoline, solvents, oil-based paints, and hydrocarbons from the petrochemical industry are also significant sources.
Interestingly enough, indoor air pollution resulting from VOCs emanating from products such as oil based paint and carpeting represents as great or greater a threat to human health.
Like VOCs, NOX are mainly produced by oil and gas, but in the case of NOx contributions to ground level ozone, a combustion process proceeds the emission. For example, the exhaust from fossil fuel combustion in our motor vehicles is the primary source, followed by fuel burning in homes, businesses, factories and power plants.
Respiratory ailments from asthma to bronchitis represent the primary health problems associated with human exposure to ground level ozone. The American Lung Association notes that anywhere from 10,000 to 15,000 people are admitted to emergency rooms each year suffering ozone exposure related illnesses. children are especially susceptible to ozone related illnesses because on average they spend more time outdoors than adults and their airways are narrower than adults.
© 2000. Patricia A. Michaels.