Introduction
Air is all around us and is everywhere and its mix of gases is essential for life. Despite the
atmosphere’s vastness, humanactivities, likethe emission of chemicalsubstances, particulate
matter (smoke and dust), and even biological materials, cause air pollution. This pollution
affects entire ecosystems, worldwide. Pollution is also a big problem indoors. Pollution, both
the outdoor and indoor varieties, cause many health problems as well as deaths. In spite of
all the dangers to human health from pollutants, there are ways for you to protect yourself.
Pollution of Outdoor Air
Air is so easy to take for granted. In its unpolluted state, it cannot be seen, smelled,
tasted, felt, or heard, except when it blows or during cloud formation. Yet its gases are very
important for life: nitrogen helps build proteins and nucleic acids, oxygen helps to power life,
carbon dioxide provides the carbon to build bodies, and water has many unique properties
which most forms of life depend on.
Outdoor air pollution consists of either chemical, physical (e.g. particulate matter),
or biological agents that modify the natural characteristics of the atmosphere and cause
unwanted changes to the environment and to human health. Primary pollutantsare
added directly to the atmosphere by such processes as fires (Figure25.2) or combustion
of fossil fuels (Figure25.3), such as oil, coal, or natural gas (Figure25.4). Secondary
pollutantsare formed when primary pollutants interact with sunlight, air, or each other.
Both types are equally damaging.
Figure 25.2: Wildfires, either natural- or human-caused, release particulate matter into the
air, one of the many causes of air pollution. ( 20 )
Most air pollutants can be traced to the burning of fossil fuels. These include the burning