What Are the Six Criteria Air Pollutants?

Six Criteria Air Pollutants

Six criteria air pollutants are the most common air pollutants which can be found in our atmosphere under the guidelines of the EPA following National Ambient Air Quality Standards.

Compared to other air pollutants, these six groups have a greater capacity to harm living creatures, cause property damage, and create a hostile environment. From Today’s Know Your Facts, let’s discuss these six criteria air pollutants and what they are capable of doing. So Read and Enjoy.

National Ambient Air Quality Standards (NAAQS)

The Ambient Air Quality Standards were imposed by the United States Environmental Agency in 1990 as part of the process of writing the Clean Air Act.

Their purpose was to determine the key elements contributing to air pollution that have an influence on public health. The primary way they did this was by dividing it into pieces.

1. Primary Standards

The Environmental Protection Agency (EPA) states that the primary goal is to preserve public health, including the health of “sensitive” populations such as people who suffer from asthma, children, and the elderly.

2. Secondary Standards

The protection of the general public needs to be the second most important thing, and this should include safeguarding against reduced visibility as well as preventing damage to animals, crops, vegetation, and buildings.

Although priorities have been separated into two regions depending on their importance, almost all the needs are essential for keeping the human civilization forward.

What Are the Six Criteria Air Pollutants?

Under the EPA regulation, these are the most commonly identified six criteria air pollutants in our atmosphere which lead higher level of risk to the public.

  1. Carbon Monoxide
  2. Lead
  3. Nitrogen Dioxide
  4. Ground level Ozone
  5. Particulate Matter
  6. Sulfur Dioxide

According to EPA guidelines the priorities of these air pollutants can be categorized as followed.

Averaging TimeLevel
Carbon Monoxide (CO)primary8 hours9 ppm
primary1 hour35 ppm
Lead (Pb)primary and
Rolling 3-month average0.15 μg/m3
Nitrogen Dioxide (NO2)primary1 hour100 ppb
primary /
1 year53 ppb
Ozone (O3)primary and
8 hours0.070 ppm
Particulate Matter
PM 2.5
primary1 year12.0 μg/m3
secondary1 year15.0 μg/m3
primary /
24 hours35 μg/m3
PM 10primary /
24 hours150 μg/m3
Sulfur Dioxide (SO2)primary1 hour75 ppb
secondary3 hours0.5 ppm
National Ambient Air Quality Standards – Reference

01. Carbon Monoxide

Carbon monoxide is known as the “silent killer” due to the fact that it is odorless, colorless, and can cause death in a very short amount of time.

The combustion process produces both carbon dioxide and carbon monoxide as a byproduct. Vehicle engines, stoves, fireplaces, and furnaces that are used in environments with insufficient quantities of oxygen are the primary sources of carbon monoxide production.

1.1 Main sources behind Carbon Monoxide

Almost all heat-related combustion process has a higher level of generating Carbon oxide. Few of them can be identified as :

Six criteria air pollutants
There are several reasons behind CO/CO2 – Six criteria air pollutants
  1. Vehicle engines
  2. Fire Places
  3. Furnaces, boilers, Grills, generators
  4. Tobacco smoke
  5. Clothes dryers
  6. Gas stoves and ovens

1.2 Symptoms of exposure to Carbon monoxide

If you are exposed to carbon monoxide due to its hidden properties it’s quite hard to respond back. But few of the following common symptoms can be identified in a CO-exposed person.

  1. Headache
  2. Shortness of breath
  3. Dizziness
  4. Feeling sick or being sick
  5. Feeling weak
  6. Confusion
  7. Chest and muscle pain

Carbon monoxide exposures can be noticed in quite potential danger locations and have a higher level of health risk. Therefore, having proper protection is much required although you have to be engaged in such hazardous places.

2. Lead

Lead, sometimes referred to as Plumbum (Pb), is a heavy metal that is produced and readily available in nature. It may easily enter the atmosphere and cause a number of dangerous medical disorders.

Due to their inclusion with lead-mixed fuels at the beginning of the industrial period, the majority of gasoline-based manufacturing industries had a higher risk environment.

However, thanks to modern science and technology, the majority of fuel can be consumed after a thorough purification process.

2.1 Main sources behind Lead

Although latest gasoline productions are in the least level of Lead ingredients. There is a number of industrial production method with a significant amount of lead as an ingredient.

  1. Cement manufacturing
  2. Lead smelters
  3. Glass manufacturers
  4. Industrial, commercial, and institutional boilers
  5. Lead-acid battery
  6. Metals processing
  7. Iron and steel foundries
  8. Copper smelters

2.2 Symptoms of exposure to Carbon monoxide

Lead poisoning can occur at any level of lead exposure and is linked to a wide range of advanced medical problems and symptoms, both in the long and short term.

The human body is capable of absorbing lead, which then deposits itself in the bones, blood, and other tissues. It is rather used as a source of constant internal exposure and is not kept there permanently.

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There are a number of health conditions caused by Lead – Six criteria air pollutants

As we become older, our bones get less mineralized, which can lead to an increase in the amount of lead that seeps into the bloodstream from bone tissue.

Here are short-term health effects when you are exposed to Lead:

  1. Abdominal pain
  2. Constipated
  3. Headachy
  4. Irritable
  5. loss of hunger
  6. Memory decline

Long-term exposure to a substance may cause depression, forgetfulness, or its more severe forms, such as high blood pressure, heart disease, kidney disease, and decreased fertility.

3. Nitrogen Dioxide

Nitrogen dioxide is an atmospheric gas that is mostly produced by the lighting process.

By breaking the triple strong connection between nitrogen and interacting with oxygen in the environment, both nitrogen dioxide and nitrogen oxide can be naturally produced.

Nitrogen oxides are the primary cause of the yellow-brown color of photochemical smog, in addition to their contribution to acid rains through their acidic nature.

3.1 Main sources behind Nitrogen dioxide

As mentioned earlier nitrogen oxide generating process needs some energy compared with other air pollutants. The main source behind this might be identified as the internal combustion in engines. Other than that

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Volcano eruption is one main reason behind NO2- Six criteria air pollutants
  1. Lightning strikes
  2. Volcanoes eruption
  3. Biological Decay
    Gives the contributes to total nitrogen dioxide in the earth’s atmosphere.

3.2 Health impact side of the Nitrogen dioxide

When talking about nitrogen dioxide’s contribution to air pollution, the most important environmental phenomenon caused by this air pollutant is acid rain.

Acid rain has an effect on forests as well as marine ecosystems, such as streams, lakes, and marshes, where fish and other creatures can become toxic.

Aside from that, it has a significant impact, both directly and indirectly, on the existence of living beings.

  1. Nitrogen dioxides, on the other hand, have direct repercussions on the health of living beings. A reason for asthma in kids
  2. Make worse the sneeze of cough conditions
  3. Malfunction of your lungs and respiratory system
  4. Increased inflammation of the airways
  5. Enhance the possibility to trigger asthma attacks

4. Ground-level Ozone

Everyone has a positive attitude toward ozone in the upper atmosphere whenever it is brought up in a conversation about the ozone level in the stratosphere.

However, once it is on the ground, its performance is not very good. The unsteady molecule of ozone is in a constant state of haste to give up its lone reactive oxygen atom and undergo the transformation into the stable form of oxygen.

Despite the fact that it is not produced directly by human activities, it is the outcome of a large number of interactions involving a wide variety of potentially harmful chemical components.

Take, for example, the reaction that takes place between the major industrial pollutants nitrogen oxides and volatile organic compounds.

When exposed to ozone, people may experience difficulty breathing as well as damage to their airways. Inhaling O3 can make asthma and other respiratory disorders much worse, just like it does with other types of pollution.

4.1 Main sources behind Ozone

Statistics provided by the EPA indicate that the greatest contributor to ground-level ozone is the photochemical reaction that takes place between two of the most prevalent classes of air pollutants: volatile organic compounds (VOC) and nitrogen oxides (NOx)

In the summer, when there is more heat and sunlight, the concentration of ozone is likely to be higher than it is in the winter.

4.2 Health impacts caused by Ozone

Ozone is a contaminant in the air that has been linked to a variety of adverse effects on human health. These effects, which can be either direct or indirect, can cause significant harm over time.

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Ozone leads a number of sicknesses – Six criteria air pollutants

Several of them can be distinguished in the following ways:

  1. Damage to the tissues of the respiratory tract
  2. Reduce the amount of air that the lungs can take in, resulting in shortness of breath
  3. Increases lung cell permeability, making them more sensitive to poisons and pathogens
  4. Causing inflammation and irritation
  5. Symptoms in coughing, chest tightness, and worsening asthma symptoms
  6. Inflammation and irritation of the human airway lining tissues

5. Particulate Matter

Particulate matter also known as PM is the collection of all suspended solid and liquid particles, many of which are dangerous.

This complicated mixture contains both organic and inorganic particles, such as dust, pollen, soot, smoke, and droplets of liquid. The size, nature, and origin of these particles vary widely.

  1. PM 10 – Coarse Particle (10 microns) – Filtered in the proximal airway, may irritate skin/mucosa
  2. PM 2.5 – Fine Particles (2.5 microns)- Reached peripheral airways, cannot enter system circulation
  3. PM 0.1 – Ultrafine Particle (0.1 microns) – Higher adsorbed toxic material on the surface, may enter systematic circulation

5.1 Main sources behind Particulate Matter

Particulate matter is constantly formed everywhere. From wood-burning stoves in the kitchen to enormous volcano eruptions, this air pollution component is widespread.

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Industrial and vehicles smoke behind the Particulate matter production -Six criteria air pollutants

Here are some of the most common sources behind the particulate particles.

Primary sources

  1. Agricultural operations
  2. Industrial processes,
  3. Combustion of wood and fossil fuels,
  4. Construction and demolition activities,
  5. Entrainment of road dust into the air.
  6. Windblown dust and wildfires.

Secondary sources

  1. SOx,
  2. NOx,
  3. VOCs,
  4. Ammonia

5.2 Harmful effect of the Particulate Matter

As the size of the particle, you intend to expose decreases, the potential level of danger rises.

Through the respiratory system, for instance, ultrafine particles smaller than 0.1 microns can easily enter the bloodstream.

Similarly, PM might have direct effects on the body due to its acute availability. Here are some prevalent medical disorders that are frequently caused by particle matter air pollution:

  1. Throat and lung irritation
  2. Coughing, sneezing, runny nose
  3. Shortness of breath
  4. Premature death in people with heart or lung disease
  5. Nonfatal heart attacks
  6. Irregular heartbeat
  7. Aggravated asthma
  8. Decreased lung function
  9. Increased respiratory symptoms
  10. Worsen the other respiratory system-based health conditions like asthma

6. Sulfur Dioxide

Sulfur dioxide is primarily generated by the combustion of sulfur-containing fossil fuels. When atmospheric Sulfur dioxide reacts with water, Sulfurous and Sulfur acids are the typical byproducts, leading directly to acid rain.

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Sulfur in fuel leads to generating sulfur dioxide -Six criteria air pollutants

We can claim that sulfur dioxide is responsible for indirect deforestation, acidification of water bodies, and degradation of material structures caused by acidified water.

6.1 The harmful effect of the Sulfur Dioxide

Similar to other acidic air pollutants, exposure to sulfur dioxide gas causes a variety of medical disorders depending on the reparative system.

Depending on your age, these effects may vary slightly.

  1. It irritates the mucous membranes of the eyes, nose, throat, and lungs.
  2. Irritation and swelling of the respiratory system, Discomfort upon taking a deep breath
  3. Coughing, throat discomfort, and difficulty breathing
  4. Influence lung function

If you have a medical history related to your respiratory system, such as asthma, sulfur dioxide can exacerbate your condition.

These six criteria air pollutants are the most widespread air pollutants in the atmosphere and are responsible for both direct and indirect harm to the life that exists on earth.

There are many other long-term physical impacts that inflict irreparable damage, in addition to the effects that it has on living creatures. Consequently, effective management of these “Six Criteria Air Pollutants” is direct assistance to the continuation of human civilization and the progression of the world.

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