6 Major Causes of Air Pollution and Most Common Pollutants

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Climate change and the ozone layer have been at the forefront of conversations for the past couple of years. But people often don’t know what is causing climate change, let alone are they discussing prevention methods. Air pollution is the leading cause of recent environmental changes we’ve seen. Crucial to our planet’s ecosystems thriving, the ozone layer is depleting from increased pollution and global warming. This phenomenon is hurting our chances of survival.

Ninety percent of people are currently breathing air that exceeds World Health Organization (WHO) pollutant guidelines. Under the 1970 U.S. Clean Air Act, the U.S. Environmental Protection Agency (EPA) can regulate air pollutant emissions. Since these emissions can cause bodily damage, the EPA sets permissible levels for these air contaminants and checks them regularly.

Learn more about air pollutants and their sources with this article. Below, we’ll cover air pollution, the most common air pollutants, their significant causes and effects and solutions to reduce pollution.


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What Is Air Pollution?

Air pollution refers to contaminated indoor or outdoor air. Pollution can be any atmospheric air alternations, whether physical, biological or chemical. Whenever contaminants like dust or smoke enter the atmosphere, vegetation, humans and other living beings may have trouble surviving. Air pollution also refers to a substance that hinders the atmosphere and ecosystem.
The composition of gases in the atmosphere sustains all living things on Earth, and any imbalance may cause harm to life.

Geometric orange background with white text. Air pollution information bolded next to smokestacks showing air pollution.

Invisible vs. Visible Air Pollution

There are two types of air pollution: Visible and invisible air pollution. Learn more about each below:

  • Visible air pollutants: These contaminants are visible. Take the smog you can see over a city, for example — this is a common visible air pollutant.
  • Invisible air pollutants: Invisible pollutants are less noticeable, but this in no way means they are less harmful. In fact, invisible air pollutants can be more deadly than visible ones. Examples of this type are sulfur dioxide, carbon monoxide and nitrogen oxides.

Sometimes people don’t realize the significant environmental effects of air pollution due to its frequent lack of visibility. Acknowledging and recognizing that invisible air pollutants exist — especially since they can be even more deadly than their visible counterparts — is essential to make a genuine difference in the amount of air pollution created.

Primary vs. Secondary Air Pollution

Air pollutants are typically considered either visible or invisible. Air pollutants generally are also either classified as primary or secondary:

  • Primary air pollutants: These are pollutants that directly result from their sources. An example of this is the sulfur dioxide emitted from factories.
  • Secondary air pollutants: Primary and secondary pollutants intermingle and react to produce these pollutants. Primary pollutants may undergo chemical reactions that produce smog, a key example of a secondary pollutant.

Knowing how to classify a specific pollutant can help narrow down the causes. Knowing the direct reasons for a type of pollution makes it easier to target them and reduce or eliminate them to cut down on air pollution. For example, interactions that cause primary pollutants also increase secondary air pollutants. If you can decrease the primary pollutants, you’ll naturally do the same for the secondary pollutants.

Ninety percent of people are currently breathing air that exceeds World Health Organization (WHO) pollutant guidelines.

Types of Air Pollutants

The top eight types of air pollutants are:

  1. Carbon monoxide
  2. Carbon dioxide
  3. Nitrogen oxides
  4. Ozone
  5. Chlorofluorocarbons (CFCs)
  6. Particulates
  7. Sulfur dioxide
  8. Volatile organic compounds (VOCs)

Understanding the different air pollution types can help you determine their causes, effects and prevention methods. Explore a few of these contaminants in further detail below.

Carbon Monoxide and Carbon Dioxide

Carbon monoxide is often known as the silent killer. The odorless and invisible substance can cause severe illness or death. It is a byproduct of the combustion process and most commonly comes from transportation sources. Carbon monoxide is harmful to the body because it inhibits the blood’s ability to deliver oxygen to the organs. At high levels, it stops oxygen delivery altogether, causing death.

Fuel-burning equipment like generators, stoves, heaters, grills and motor vehicles contribute to carbon monoxide buildup in enclosed spaces. Fuels that can create carbon monoxide include:

  • Gasoline
  • Kerosene
  • Propane
  • Coal
  • Wood
  • Oil
  • Natural gas
  • Methane

The carbon monoxide these appliances produce is usually not hazardous with proper ventilation systems. However, a carbon detector or ventilation system that is not working correctly or experiences incorrect operator use can cause dangerous levels of carbon monoxide.

In contrast, carbon dioxide is a greenhouse gas and a natural byproduct of respiration. However, carbon dioxide is also associated with the burning of fossil fuels.

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Nitrogen Dioxide and Nitrogen Oxides

Nitrogen dioxide is part of a group of highly reactive gases called oxides of nitrogen or nitrogen oxides. Nitrogen dioxide is a standard indicator gas for this group. Fuel-burning is a significant cause of nitrogen dioxide air pollution. Common air pollution sources include:

  • Motor vehicles like cars, buses and trucks
  • Off-road equipment
  • Power plants

Nitrogen oxides contribute to fine particle pollution and ground-level ozone and cause health issues like respiratory distress.


Ozone is made of three oxygen atoms and can either help or harm human health and the environment depending on its atmospheric location. Stratospheric ozone is located in the atmosphere’s upper layer and helps protect living things from the sun’s ultraviolet radiation. People who talk about an ozone hole refer to this beneficial ozone layer. However, manmade chemicals have damaged the stratospheric ozone layer.

Contrasting to stratospheric ozone, ground-level ozone can trigger various health problems, especially for children, the elderly and people with lung diseases like asthma. In fact, ground-level ozone significantly contributes to smog production.

Power plants, motor vehicles, refineries, chemical plants and other sources emit pollutants that react in sunlight. Hot, sunny urban environments are most likely to foster a toxic level of ground-level ozone. However, it can still reach high levels in the cold and impact rural areas due to wind travel.

Particulate Matter

Processes that create dust, like wood burning, motor vehicle operation, industrial plant smokestack emissions and dirt that gathers in the air due to wind, cause particulate matter air pollution.

Different pollution sources also present a range of particulate matter sizes. Soil contributes to larger particles, while fossil fuel burning causes smaller particle emissions. Particulate matter also falls into two categories:

  • Primary: Primary particulate matter results from direct emissions, such as from a smokestack or tailpipe
  • Secondary: Chemical reactions from downwind gaseous emissions cause the formation of secondary particulate matter. This form of pollution is extremely harmful to the body.

Geometric orange background with white text. Air pollution information bolded next to smokestacks showing air pollution.

Sulfur Dioxide

Burning fuels that contain sulfur, like coal and oil, contributes to sulfur dioxide formation. This colorless, reactive gas causes respiratory damage and can heighten symptoms from conditions like asthma. Power plants and industrial boilers are significant sources of this kind of pollution, as areas close to large fuel-burning industrial centers typically have higher sulfur dioxide air concentrations. Metal ore extractions and locomotive, large ship and non-road equipment fuels containing high sulfur levels are less significant sources.

What Are the Most Common Causes of Air Pollution?

Air pollution is caused by both naturally occurring and manmade pollution sources, both of which may harm human health. Natural sources include volcanic eruptions, dust carried by the wind and gases released by living beings. Manmade activities that cause air pollution include motor vehicle use, fossil fuel burning and agriculture.

The most common air pollution sources include:

  1. Fossil fuel burning: Fossil fuel burning like that which happens in factories or other industrial applications emits sulfur dioxide into the atmosphere.
  2. Agriculture: Agricultural activities frequently emit ammonia, a severely hazardous atmospheric gas. Insecticides, pesticides and fertilizers cause both chemical air and water pollution. Farmers also set controlled fires to fields and old crops to clear them for the next round of sowing. However, this burning also releases harmful pollution-causing gases into the air.
  3. Landfill waste: Landfills are land areas into which humans deposit or bury waste, which then generates methane. Methane is a significant greenhouse gas that is highly flammable and very hazardous.
  4. Industry and factory emissions: Manufacturing industries deplete air quality by releasing hydrocarbons, carbon monoxide, organic compounds and other chemicals into the air.
  5. Mining operations: During mining, large equipment extracts underground minerals. However, this process also releases dust- and chemical-based air pollutants. Nearby residents and workers often suffer health consequences as a result of mining.
  6. Indoor sources: Substances like household cleaning products and painting supplies, for example, contribute to indoor air pollution.

Air Pollution Effects

Now that we know the types of air pollution and what causes them, it’s essential to understand how it affects public health and the environment. Air pollution impacts human health in different ways depending on the exposure type, level and length of exposure. However, different individuals may experience various effects, such as increased respiratory conditions or age-related complications.

Here are seven effects of air pollution:

  1. Public health problems: Air pollution contributes to several respiratory and heart problems, including asthma, chronic bronchitis, emphysema, heart attacks, strokes and cancer. More than 4 million people each year die from air pollution-related complications.
  2. Child health problems: During pregnancy, exposure to high air pollution can cause miscarriages, premature birth, autism, asthma and spectrum disorders in young children. It can also damage early brain development in a child and cause pneumonia, which kills almost a million children under five years old. Children are at a greater risk of short-term respiratory infections and pulmonary diseases in areas exposed to air pollutants.
  3. Global warming: This issue is probably one of the most well-known effects of air pollutants. Increasing temperatures across the globe have led to elevated sea levels from melting icebergs, resulting in habitat loss and emphasizing the need for preservation actions.
  4. Acid rain: Harmful gases like nitrogen oxides and sulfur oxides are released into the atmosphere when fossil fuels are burned. Rain mixes with air pollutants to form acid rain, damaging humans, animals, landscapes and plants. Sensitive ecosystems such as lakes and forests are especially susceptible to acid rain damage.
  5. Eutrophication: Eutrophication happens when excess algae form in bodies of water due to the high nitrogen level of some pollutants. Many lakes and ponds typically have this green-colored, eutrophication-based algae. Heavy algae can negatively impact aquatic species like fish and plants.
  6. Wildlife harm: Animals may change habitats due to air pollution. Further, toxic particulates can also impact aquatic animals when pollutants contaminate the water.
  7. Depletion of the ozone layer: The ozone layer protects the Earth’s inhabitants from the sun’s damaging ultraviolet (UV) rays. However, atmospheric chlorofluorocarbons and hydrochlorofluorocarbons are contributing to ozone layer depletion. A thinning ozone layer causes increased UV rays to reach the Earth, resulting in potential skin and eye-related problems. Sensitive ecosystems like parks, forests and wilderness sanctuaries can experience harm due to elevated ozone levels.

This list is just the beginning. If air pollution continues without any attempts to reduce or prevent it, these issues will only continue to grow and worsen.

Air Pollution Solutions

So, how do we reduce air pollution to prevent the harmful and hazardous effects listed above? These are some solutions to air pollution that everybody could do to help:

  1. Use public transportation: Public transportation helps reduce pollution, as people can get where they need to go with fewer pollutant-emitting vehicles. Carpooling is also an excellent option to help save energy and money. Burning less gasoline due to personal vehicles helps fight the air pollution that contributes to climate change. Use more sustainable transportation options like walking, using a bike, buying an electric car or ride-sharing whenever possible to prevent air pollutant emissions.
  2. Improve household practices: Rather than using wood, utilize gas logs around the home. Try to decrease how often you use gas-powered landscaping equipment. Lighting open fires in your yard also contributes to increased air pollutants. Following environmentally friendly practices like composting, mulching organic waste or using green cleaning products reduces household emissions.
  3. Be energy-conscious: You can help reduce air pollution emissions in residential applications by turning off lights and fans when leaving the house. Burning fossils fuels produces electricity. Therefore, you can decrease your fossil fuel emissions through energy-saving practices.
  4. Reduce, reuse, recycle: Reduce, reuse and recycle is more than just a fun saying — it also helps save the environment. Instead of throwing things away, donate them or use them for an alternative purpose. Store cereals or other dry foods in old jars and recycle the boxes, and donate items to the needy to reduce waste.
  5. Emphasize renewable resources: Energy sources like solar, geothermal and wind are more sustainable than fossil fuel alternatives. In fact, governments offer grants for eco-conscious consumers who are interested in sustainable power for their homes. If you review sustainable energy options, you may find you can easily use wind or solar electricity sources in your home.
  6. Prioritize energy efficiency: Consider which devices may be more energy-efficient than high energy consuming alternatives. For example, CFL lights last longer and use less electricity, leading to lower bills and reducing air pollution.
  7. Buy local groceries: Transporting food via truck or air across the country burns more fossil fuels. Therefore, shopping locally can both decrease fossil fuel use and support your local community.
  8. Support eco-friendly local and national politicians and leaders: Politicians and other community leaders are crucial in the clean air and water crusade. These individuals have the potential to make a more significant impact on public health and environmentalism.
  9. Avoid open burning: A significant cause of particulate matter, open burning refers to setting fire to landscaping debris, trash and other waste. Practice more sustainable ways to dispose of waste through incineration, such as converting it to biogas.

Individuals, companies and governments all strive to reduce air pollution to mitigate the impact of global warming. Modern innovation can help create alternative energy sources to reduce air pollutants.

Help Protect Our Air

Take your company to the next level by ensuring it is limiting air pollution. MACH Engineering is a design and manufacturing company that provides corporations, local plants and fabricators with energy-friendly, innovative products.

We provide high-quality engineering design equipment and services for air and water pollution control. Products include:

MACH caters to various industries, including:

  • Chemical and food processing
  • Plating and metal finishing
  • Ethanol production plants
  • Petrochemical
  • Odor controls
  • Refineries
  • Pharmaceuticals
  • Water and wastewater
  • Pulp and paper

Take steps today to help prevent air pollution’s hazardous effects by partnering with MACH Engineering to ensure your company practices sustainability in its operations. Contact us today to discover MACH’s emission control solutions!