Dr. Ray L. Winstead
Professor of Biology, Indiana University of Pennsylvania

Air Pollution


        A general trend in modern, industrial societies is to first have water pollution and then have air pollution.  The basic, fundamental cause of air pollution is overpopulation.


Air pollution exists in 3 categories:


Category 1: Personal air pollution – smoking

        Smoking is a direct cause of serious health problems to the smoker (e.g., chronic pulmonary disease, cardiovascular disease, and lung cancer), and also tobacco smoke presents a serious risk to the health of nonsmokers as well.


Sidestream smoke – the smoke from the burning end – has higher concentrations of noxious, dangerous compounds than the mainstream smoke inhaled by the smoker, because of the filtering effect of the cigarette, i.e. nearby nonsmokers may breathe in even worse smoke than the smokers themselves.


Usually the smoker is not sensitive to the smell because of the destructive effects of smoke on the inner lining of his or her nose.


On average a woman will die 16 years earlier if she smokes.

On average a man will die 12 years earlier if he smokes.


 (Note illustration of disruption of major mechanism of disease prevention (also asbestos fibers).


Osteoporosis is the loss of calcium from bone, causing bone fractures.  Smokers inhale cadmium in tobacco smoke and this stimulates the release of calcium from bone.


Smoking constricts blood vessels and reduces blood flow, e.g., men who smoke have decreased erections in comparison to nonsmokers.


Children of smokers are more likely to have respiratory illnesses and slower intellectual development.

If a baby is in a room where smoking has occurred, the risk of sudden-infant-death syndrome (SIDS) increases 800%.  (Two-thirds of SIDS cases are documented to be linked to tobacco smoke.)


Statistics show that smokers are 50% more likely to have a car accident than nonsmokers.  No one knows the direct cause, but it has been suggested that smoking may just be an index of poor judgment, rather than a direct cause of an accident.


Category 2: Occupational air pollution

Category 3: Community air pollution

        A. Sources and Pollutants

            1. Natural Sources, e.g., smoke from a forest fire set by lightning, dust. 

            2. Man-made sources.  The most important source of man-made air pollution is incomplete combustion of fossil fuels.  In the USA the highest percentage of man-made air pollution comes from transportation.


        B. General Adverse Effects
            1. Economic Losses, e. g., crop damage, deteriorating materials, property devalued.
            2. Health Hazards, e. g., Respiratory diseases, such as chronic bronchitis (excessive mucus), asthma (air passages narrow), pulmonary emphysema (alveoli destroyed).
            3. Personal Discomfort, e.g., eye irritation.

            4. Aesthetics – pertaining to the senses, e.g., dark skies or offensive odors: category of no real, physical damage – just insults the senses.


        C. Major Pollutants

            1. Carbon Monoxide (CO)

Estimated to be 1/2 of all man-made air pollution - 90% of this comes from automobiles by incomplete combustion of gasoline.


            2. Greenhouse Gases

These gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth’s surface, some of it is reflected back towards space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere. Over time, the amount of energy sent from the sun to the Earth’s surface should be about the same as the amount of energy radiated back into space, leaving the temperature of the Earth’s surface roughly constant.  Many gases exhibit these “greenhouse” properties. Some of them occur in nature (water vapor, carbon dioxide, methane, and nitrous oxide), while others are exclusively human-made (like gases used for aerosols).  Levels of several important greenhouse gases have increased by about 25 percent since large-scale industrialization began around 150 years ago.  Given the natural variability of the Earth’s climate, it is difficult to determine the extent of change that humans cause. In computer-based models, rising concentrations of greenhouse gases generally produce an increase in the average temperature of the Earth. Rising temperatures may, in turn, produce changes in weather, sea levels, and land use patterns, commonly referred to as “climate change.” Assessments generally suggest that the Earth’s climate has warmed over the past century and that human activity affecting the atmosphere is likely an important driving factor. (source: U. S. Department of Energy)

            3. Sulfur Oxides

The main pollutant in this group is sulfur dioxide which comes from the incomplete combustion of fossil fuels, especially coal and oil.  Most of the pollution comes from electric power generating plants.  Sulfur dioxide is an irritant gas that causes health problems, e. g, more cases of bronchitis, paralyzes cilia in respiratory tract, changes into sulfuric acid to produce acid rain that damages vegetation and corrodes metal.


            4. Photochemical Pollution = photochemical smog.

Photochemical pollutants are created by chemical reactions of other pollutants already in the air and stimulated to occur by the presence of sunlight.  Note that photochemical pollutants are not emitted directly into the air.  The pollutants that contribute to the production of photochemical pollutants are the hydrocarbons and nitrogen oxides.  The problem hydrocarbons come from incomplete combustion of gasoline in automobiles.  The direct effects of hydrocarbons are small – the problems develop because of later chemical reactions.  Nitrogen oxides have some adverse, dangerous effects of their own: causes formation of acid rain, nose and eye irritation, offensive smell.  Nitrogen oxides are also produced by incomplete combustion, e. g., from power plants and jet airplanes.


The big problem comes about when the hydrocarbons and nitrogen oxides interact in the atmosphere to produce photochemical pollutants.  The resultant photochemical pollutants have very substantial, direct and harmful results.  Examples of photochemical pollutants include ozone, PAN (peroxyacyl nitrate), and formaldehyde.  These are very toxic and deadly to living organisms (e.g., destroys plant cells and damages respiratory system).  Note that ozone is deadly to breathe but essential in the upper atmosphere to decrease UV light.  (Note: Ultraviolet light is very high energy and has the ability to break DNA and cause cancer.  American Cancer Society:  “Do not use tanning booths.  They increase your risk of getting skin cancer.”)


            5. Particulates

Particulates are solid or liquid particles dispersed in the air, e. g., coal dust, sulfuric acid mist.  Particulates arise mainly from industries and electric power plants, especially from those using coal.  Particulate pollution has been linked to causing lung cancer, stomach cancer, and bronchitis.


One conclusion for this section is that if we solve our energy problems by going to renewable resources, we will basically solve most of our air pollution problems.


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Dr. Ray L. Winstead
Direct e-mail Link: RWinstea@iup.edu