Carbon monoxide arises from the incomplete combustion of organic material. Of principal concern is its generation by the internal combustion engine and by home heating units, particularly in poorly ventilated areas. Carbon monoxide emission by automobiles in closed garages and by unvented space heaters results in numerous deaths each year. Following inhalation, carbon monoxide binds to hemoglobin, displacing oxygen and forming carboxyhemoglobin. This decreases the oxygen-carrying capacity of the blood and impairs the blood cells' ability to release bound oxygen. The resulting hypoxia is the principal mechanism of carbon monoxide toxicity.

Nitrogen oxides, principally nitrogen dioxide, and ozone are classified as oxidizing pollutants. The major source of nitrogen dioxide is the internal combustion engine. Photolysis of nitrogen dioxide by ultraviolet radiation liberates oxygen atoms, which can then combine with molecular oxygen to form ozone. Both gases cause irritation of the deep lung and can result in increased susceptibility to respiratory infection, pulmonary edema, and impaired lung function.

Oxides of sulfur (principally sulfur dioxide) are generated during the burning of fossil fuels, most notably coal, and are classified as reducing pollutants because of

TABLE 7.2 Some Specific Antidotes for Toxic Drugs and Chemicals



Mechanism of Action


Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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