8

Air and Air

Pollution

LONG-DISTANCE TRANSPORT

OF AIR POLLUTION

P

ersistent toxic compounds are found in the Yukon

(in northwestern Canada) and in other pristine

arctic regions, far from where they were originally

produced. This occurs through the global distillation

effect, in which chemicals enter the atmosphere in

warm regions and move to areas at higher, cooler

latitudes, where they are deposited on the surface. The

chemicals are then available to be absorbed, inhaled, or

ingested by organisms at these distant locations.

Chemicals concentrate in the body fat of animals at

the top of food chains, including humans (see Chapter 4).

When an Inuit woman consumes a single bite of raw

whale skin, she ingests more toxic PCBs than scientists

think should be consumed in a week (see photograph).

Five times as much PCB is found in the breast milk of Inuit

women than in the milk of women who live in southern

Canada. Persistent organic pesticides also concentrate in

the milk of polar bear mothers (see graph).

Atmospheric conditions also cause pollutants

from Asia to move east across the Pacific Ocean.

In 1998 a Chinese dust storm produced a visible cloud

of particulate matter that transferred toxic metals

from ore smelters in Manchuria to the United States.

Around the world, the air we breathe can be

contaminated with a variety of pollutants. Because

air pollution causes many health and environmental

problems, most highly developed nations and many

developing nations have policies and regulations

limiting emissions from transportation, industry,

and even households.

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