Sources and Effects of the 9 Major Air Pollutants
What Is Air Pollution?
Air pollution takes place when a large quantity of dust, soot, bacteria, and other harmful gases get into the air and is considered the most harmful form of pollution. There are four principal sources of air pollution. The first cause is mobile sources such as cars, buses, planes, trucks, and trains. Secondly, the 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 the 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.
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:
- Ozone (O3)
- Carbon Monoxide (CO)
- Nitrogen Dioxide (NO2)
- Particulate Matter
- Sulfur Dioxide (SO2)
- Toxic Air Pollutants
- Stratospheric Ozone Depleters
- Greenhouse Gases
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 of Ozone
Effects of Ozone
Coal and other fossil fuels
Volatile compounds from factories
Volatile compounds from trees
Destroy plants and crops
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 of Carbon Monoxide
Effects of Carbon Monoxide
Engines of cars
Oxygen loss in the body
Factories that burn fossil fuels
Triggers heart diseases
Hot water heater
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 of Nitrogen Dioxide
Effects of Nitrogen Dioxide
Nitrogen reacts with oxygen
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 of Particulate Matter
Effects of Particulate Matter
Burning of fuel
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 of Sulfur Dioxide
Effects 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
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 of Toxic Air Pollutants
Effects of Toxic Air Pollutants
Food and Water Supplies
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 of Stratospheric Ozone Depleters
Effects of Stratospheric Ozone Depleters
Harm plants and animals
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 of Greenhouse Gases
Effects of Greenhouse Gases
Burned fossil fuels
Higher sea levels
Lead is a highly toxic elemental blue-gray metal found naturally in the environment and manufactured products.
Sources of Lead
Effects of Lead
Damages central nerve system
Damages mental development of children
Lower IQ for children
- Changing Air Quality | Clean Air Acts | Great London Smog
The story of "The Great Smog of London" and the Clean Air Acts passed as a solution after the incident.
- Where Does Air Pollution Come From? - Air (U.S. National Park Service)
Sources and types of air pollution. It explains the transportation of air pollution through the air.
Which among the air pollutants do you think is on extreme levels?
Questions & Answers
© 2018 John Ray