Air Pollution Explains

 Air Pollution

Introduction

Air pollution is the presence of gaseous and particulate contaminants in the earth's atmosphere. Chemicals discharged into the air that have a direct impact on the environment are called primary pollutants. These primary pollutants sometimes react with other chemicals in the air to produce secondary pollutants. Air pollution is typically separated into two categories: outdoor air pollution and indoor air pollution.

Types of Air Pollution

Outdoor Air Pollution

Outdoor air pollution involves exposures that take place outside of the built environment. Examples include:

• Fine particles produced by the burning of coal
• Noxious gases such as sulfur dioxide, nitrogen oxides and carbon monoxide
• Ground-level ozone and tobacco smoke.

Indoor Air Pollution

Indoor air pollution involves exposures to particulates, carbon oxides, and other pollutants carried by indoor air or dust. Examples include:

• Gases
• Household products and chemicals
• Building materials (asbestos, formaldehyde, lead, etc.)
• Outdoor indoor allergens (cockroach and mouse dropping, etc.)
• Tobacco smoke
• Mold and pollen.

Sources of Air Pollution

Stationary and Area Sources

A stationary source of air pollution refers to an emission source that does not move, also known as a point source. Stationary sources include factories, power plants, dry cleaners, and degreasing operations. The term area source is used to describe many small sources of air pollution located together whose individual emissions may be below thresholds of concern, but whose collective emissions can be significant. Residential wood burners are a good example of a small source, but when combined with many other small sources, they can contribute to local and regional air pollution levels. Area sources can also be thought of as non-point sources, such as construction of housing developments, dry lake beds, and landfills.

Mobile Sources

A mobile source of air pollution refers to a source that is capable of moving under its own power. In general, mobile sources imply "on-road" transportation, which includes vehicles such as cars, sport utility vehicles, and buses. In addition, there is also a "non-road" or "off-road" category that includes gas-powered lawn tools and mowers, farm and construction equipment, recreational vehicles, boats, planes, and trains.

Agricultural Sources

Agricultural operations, those that raise animals and grow crops, can generate emissions of gases and particulate matter. For example, animals confined to a barn or restricted area (rather than field grazing), produce large amounts of manure. Manure emits various gases, particularly ammonia into the air. This ammonia can be emitted from the animal houses, manure storage areas, or from the land after the manure is applied. In crop production, the misapplication of fertilizers, herbicides, and pesticides can potentially result in aerial drift of these materials and harm may be caused.

Natural Sources

Although industrialization and the use of motor vehicles are overwhelmingly the most significant contributors to air pollution, there are important natural sources of "pollution" as well. Wildland fires, dust storms, and volcanic activity also contribute gases and particulates to our atmosphere. Unlike the above mentioned sources of air pollution, natural "air pollution" is not caused by people or their activities.

Common Air Pollutants

The commonly found air pollutants (also known as "criteria pollutants") are:

1. Particle pollution (often referred to as particulate matter)
2. Ground-level ozone
3. Carbon monoxide
4. Sulfur oxides
5. Nitrogen oxides
6. Lead

These pollutants can harm health and the environment and cause property damage. Of the six pollutants, particle pollution and ground-level ozone are the most widespread health threats.