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Sources and Effects of the 9 Major Air Pollutants

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JR has a Bachelor of Science in Civil Engineering and studied Environmental Engineering as a section of their curriculum.

What Is Air Pollution?

Air pollution is considered the most harmful form of pollution and takes place when a large quantity of dust, soot, bacteria, or other harmful gases get into the air. There are four principal sources of air pollution. The first cause is mobile sources such as cars, buses, planes, trucks, and trains. Second are stationary sources such as power plants, oil refineries, industrial facilities, and factories. Third are area sources such as cities, agricultural areas, and wood burning fireplaces. The last main causes of air pollution are natural sources such as wind-blown dust, forest fires, and volcanoes.

Deadliest Air Pollution Recorded in History

Have you heard the story of "The Great Smog of London"? During the first week of December in 1952, London became unusually cold. Residents did not recognize that it was something serious. Then, the air began condensing into fog early on December 5. The fog mixed with smoke from domestic fires and vehicular and factory emissions made the smog so thick that they took many parts of London to a standstill.

Public officials did not recognize that the great smog was the most deadly air pollution until records showed up. The air pollution happened in London caused different diseases like Bronchitis and Pneumonia wherein 4000 people died in the first five days and almost 8000 recorded deaths in the next several months. As a result of the disaster, they passed its first Clean Air Act of 1956. Below is a video of a brief explanation of why such a tragedy occurred.

Air Pollutant Classification

There are two classifications for air pollutants, the primary and secondary pollutants. Usually, all primary pollutants come from direct principal sources such as mobile, stationary, and agricultural sources of air pollution. On the other hand, secondary pollutants form when two or more primary pollutants react in the atmosphere.

Classifications of Air Pollutants

Classifications of Air Pollutants

Primary air pollutants are air pollutants emitted directly from sources to the atmosphere. Some of the examples of primary pollutants are NOx from automobile exhaust, carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen oxide, nitrogen dioxide, most hydrocarbons, and most suspended particles.

Secondary air pollutants are the products of primary pollutants chemically bonded. One typical example of secondary pollutants is acid rain formed when sulfur dioxide or nitrogen oxides react with water. Additional examples of secondary air pollutants are nitric acid, sulfur trioxide, sulfuric acid, hydrogen peroxide, ozone, nitrates, sulfates, and other salts.

Nine (9) Major Air Pollutants

The Environmental Protection Agency (EPA) has set National Ambient Air Quality Standards (NAAQS) for general air pollutants. The nine major air pollutants are:

  1. Ozone (O3)
  2. Carbon Monoxide (CO)
  3. Nitrogen Dioxide (NO2)
  4. Particulate Matter
  5. Sulfur Dioxide (SO2)
  6. Toxic Air Pollutants
  7. Stratospheric Ozone Depleters
  8. Greenhouse Gases
  9. Lead

1. Ozone

Ozone (O3) is a secondary pollutant gas produced when two primary pollutants react in sunlight and stagnant air. Another term for ozone is bad ozone. The elements that form ozone are nitrogen oxides, volatile organic compounds, and ultraviolet radiation. That is why ozone is abundant during summer because of the high amount of sunlight present.

You can find ozone in two places. First is near the ground (the troposphere) which is a significant part of smog and the second one is higher in the air (the stratosphere) which helps in blocking the radiation from the sun.

Sources and Effects of Ozone as Air Pollutant

Sources of OzoneEffects of Ozone

Burning gasoline

Asthma attacks

Coal and other fossil fuels

Sore throats

Volatile compounds from factories


Volatile compounds from trees

Breathing difficulty

Ultraviolet radiation

Premature death


Destroy plants and crops

Sources of Ozone

Sources of Ozone

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2. Carbon Monoxide

Carbon Monoxide is a primary pollutant gas that comes from the burning of fossil fuels. Carbon monoxide is an air pollutant that is odorless and colorless. It is recognized as a dangerous gas since you cannot see or smell it. When you become exposed to carbon monoxide, the molecules of the gas will displace the oxygen in your body that could lead to poisoning.

Sources and Effects of Carbon Monoxide as Air Pollutant

Sources of Carbon MonoxideEffects of Carbon Monoxide

Engines of cars

Oxygen loss in the body





Factories that burn fossil fuels


Stove top

Triggers heart diseases

Clothing dryer


Hot water heater


Sources of Carbon Monoxide

Sources of Carbon Monoxide

3. Nitrogen Dioxide

Nitrogen Dioxide is a reddish-brown gas that also comes from the burning of fossil fuels. It belongs to the group of gases called nitrogen oxides (NOx). The are two ways a nitrogen dioxide forms - burning nitrogen in fuel, or nitrogen in the air reacting with oxygen at very high temperatures. Nitrogen dioxide can also respond in the atmosphere forming ozone, acid rain, and particles.

Sources and Effects of Nitrogen Dioxide as Air Pollutant

Sources of Nitrogen DioxideEffects of Nitrogen Dioxide

Power plants


Car engines


Nitrogen reacts with oxygen

Respiratory infections


Acid rain

4. Particulate Matter

Particulate Matter or Particle Pollution can either be a solid or liquid matter suspended in the air. The sizes of particulate matter must be less than 0.1 millimeters wide to remain in the atmosphere. Particulate Matter has two types - coarse particles and fine particles.

Sources and Effects of Particulate Matter as Air Pollutant

Sources of Particulate MatterEffects of Particulate Matter

Road dust



Respiratory Problems

Construction debris

Premature death

Burning of fuel


Power plants


Sources of Particulate Matter

Sources of Particulate Matter

5. Sulfur Dioxide

Sulfur Dioxide is a corrosive gas that cannot be noticed or smelled at base levels but can have a "rotten egg" smell at above levels. Sulfur dioxides are compounds of sulfur and oxygen molecules. Like nitrogen dioxide, sulfur dioxide can respond to the atmosphere to form acid rain as well. Electric power companies that burn coal are a principal source of sulfur oxides.

Sources and Effects of Sulfur Dioxide as Air Pollutant

Sources of Sulfur DioxideEffects of Sulfur Dioxide

Burning of coal in power plants


Burning of oil in power plants


Factories making papers, chemicals, or fuel



Eye, nose, and throat irritations


Damage infrastructures

6. Toxic Air Pollutants

There are some other toxic air pollutants which contain chemicals suspected to cause cancer. Examples are benzene, arsenic, asbestos, dioxin, perchloroethylene, and methylene chloride. Perchloroethylene is a hazardous air pollutant emitted from dry cleaning facilities while methylene chloride comes from solvent and paint industries.

Sources and Effects of Toxic Air Pollutants

Sources of Toxic Air PollutantsEffects of Toxic Air Pollutants

Chemical plants


Building materials


Food and Water Supplies

Birth deficiency


Breathing problems

7. Stratospheric Ozone Depleters

Stratospheric Ozone Depleters are substances that can deplete the ozone layer in the stratosphere. These substances are chlorofluorocarbons, halons, and other chemicals comprising bromine and chlorine.

Sources and Effects of Stratospheric Ozone Depleters as Air Pollutant

Sources of Stratospheric Ozone DepletersEffects of Stratospheric Ozone Depleters


Skin cancer


Eye problems

Aerosol cans

Harm plants and animals

Fire extinguishers


Industrial Solvents


Sources of Stratospheric Ozone Depleters

Sources of Stratospheric Ozone Depleters

8. Greenhouse Gases

Greenhouse gases are gases that absorb and emit radiant energy from the sun acting like a glass in a greenhouse. It stays upright in the air for a very long time confining the sunlight causing the planet to become warm. There are some significant greenhouse gases that we need to survive - carbon dioxide, methane, and nitrous oxide. Carbon dioxide is the most significant greenhouse gas among the three. Without carbon dioxide, plants cannot produce food essential for us humans to live.

Sources and Effects of Greenhouse Gases as Air Pollutant

Sources of Greenhouse GasesEffects of Greenhouse Gases

Burned fossil fuels

Temperature changes


Higher sea levels

Rice paddies

Forest decomposition

Industrial sources

Coast damage

Decaying plants

Health problems

9. Lead

Lead is a highly toxic elemental blue-gray metal found naturally in the environment and manufactured products.

Sources and Effects of Lead as Air Pollutant

Sources of LeadEffects of Lead

Unleaded gasoline

Damages central nerve system

Power plants

Damages mental development of children

Lead paint

Lower IQ for children

Lead pipes

Kidney problem


Heart attacks




This content reflects the personal opinions of the author. It is accurate and true to the best of the author’s knowledge and should not be substituted for impartial fact or advice in legal, political, or personal matters.

© 2018 Ray

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