What Are The Differences Between Primary And Secondary Pollutants?

Motor vehicle emissions are a type of primary pollutant.
Motor vehicle emissions are a type of primary pollutant.

Pollutants Released Into The Environment

Research on environmental health has indicated an increased amount of pollutants in the Earth’s atmosphere, waterways, and soil. These pollutants come from a number of sources including: the agricultural industry, manufacturing plants, and urban centers. As countries around the world continue to industrialize their economies and the cities continue to undergo rapid urbanization, the amount of pollutants released into the environment is steadily increasing. Even everyday, seemingly ordinary activities like driving personal automobiles to work makes an impact on the environment by emitting large quantities of contaminants.

Understanding details about which contaminants are making their way into the soil, waterways, and air is important in order to combat any damage they may cause. Some important details include: pollutant source, manner of emission, and interactions in the environment. Without this information, preventing harmful consequences is difficult, if not impossible. This article focuses on the types of pollutants found in air pollution: primary and secondary.

What Is A Primary Pollutant?

A primary pollutant is emitted from a single source into the air, where it may contaminate natural habitats and concentrate exponentially over time. Some of the most common primary pollutants include: carbon dioxide, nitrogen oxide, chlorofluorocarbons, sulphur dioxide, volatile organic compounds, mercury, and particulate matter. These emissions make their way into the atmosphere by natural causes, like volcanic eruptions, and by human activity, like the manufacturing industry. The main contributor of primary pollutants to the atmosphere, however, is motor vehicle emissions. Burning gasoline and diesel fuel in combustion engines results in significant exhaust emissions.

What Is A Secondary Pollutant?

A secondary pollutant is not a direct emission from a single source. Instead, these pollutants are formed when 2 or more primary pollutants react with each other in the atmosphere. An example of this can be seen when nitrogen oxide and hydrocarbons react with sunlight, resulting in ozone. Another example of a secondary pollutant occurs when nitrogen oxide and sulphur dioxide react with water in the atmosphere, creating acid rain. Other secondary pollutants include: smog, nitrogen dioxide, peroxyacyl nitrates, and sulfuric acid.

The creation of secondary pollutants is influenced by a number of factors, including: particle sizes, concentration levels, UV strength, and external weather conditions. Many experts report that secondary pollutants can cause much greater damage to the environment than primary pollutants. Additionally, these substances are of particular concern given their variability and propensity to form from a wide range of primary pollutants.

How Do Primary Pollutants React In The Atmosphere?

As previously mentioned, several factors can contribute to the creation of secondary pollutants in the atmosphere. One of the most important of these is considered particle size. These solid particles, which can be carried through the air at any time, absorb a small amount of gas particles into their surface level. When this absorption occurs, the gases become stronger, effectively increasing their level of toxicity.

Effects Of Primary And Secondary Pollutants

Researchers have identified a link between primary pollutants and global climate change. Additionally, secondary pollutants are known to cause a number of negative impacts on the environment as well. Primary pollutants in particular are known for their corrosive properties, which can cause damage to ecosystems as well as manmade infrastructure.

When pollutants in the atmosphere present as smog, they may reduce the visibility of an area or cause respiratory and cardiac problems in humans. Some health professionals believe that smog leads to asthma in children as well an increased risk of pneumonia. Animals may also be affected by poor air quality, which forces them to seek out new habitats. This secondary pollutant has become a common occurrence in urban areas around the world, particularly in cities with high population densities. Photochemical smog may consist of several secondary pollutants, such as ozone and nitric acid.

In addition, ozone depletion is one of the effects of primary and secondary pollutants in the atmosphere. Ozone depletion is caused by chlorofluorocarbons, which makes the ozone layers grow thin. Thinner, or in some cases non-existent, ozone permits dangerous solar UV rays to reach the surface of the earth. These UV rays are harmful for plant life and humans. In humans, it can cause vision problems and skin cancer.

Acid rain, a secondary pollutant, occurs anywhere near fossil fuel-burning power plants. This rain, filled with nitrogen and sulphur oxides, flows into waterways, changing marine habitats. Additionally, it may have a negative impact on agriculture harvest yield.

As previously mentioned, primary and secondary pollutants have also been connected to global climate change. One of the results of this has been increasing temperatures around the world. As temperatures increase in colder regions, the melting snow, ice, and glaciers are contributing to rising sea levels. Increases in sea levels are threatening coastal communities, particularly on island nations. As temperatures increase in warmer regions, rainfall decreases. These increased instances of drought often result in desertification.

High levels of pollutants can also be carried to the earth’s surface, where it seeps into groundwater and washes away into waterways. One of the results of this is eutrophication, which is a higher than average concentration of nitrogen in the water. This nitrogen content creates the perfect environment for algae, which soon begins to take over the marine habitat. As algae grows thicker, it blocks the sunlight from entering the water, which prevents the growth of other oxygen-creating marine plants. With less plants in the waters, fish and other marine species are unable to obtain all of their dietary needs. Eventually, eutrophication results in decreased marine animal life as well.

Preventing Air Pollution

Given that private transportation is one of the main contributors of primary pollutants to the atmosphere, reducing the use of combustion engine vehicles is one of the principal means of preventing air pollution. Experts suggest increasing the use of public transportation or to ride to work in carpools, anything to reduce the number of automobiles on the road.

Other ways to prevent primary pollutants from entering the atmosphere (and resulting in secondary pollutants) is by investing in renewable energy. Showing support for and demanding renewable energies could prompt more governments around the world to invest in solar, wind, and hydro infrastructure to meet energy needs. Where this is not available, concerned individuals can reduce their use of energy by taking some simple steps throughout their day, like turning off the lights and other electronic appliances when not in use.

Staying informed and urging governments and private organizations to take steps to reduce primary pollutant emissions is one of the best ways to fight air pollution and climate change.


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