Why Air Quality Changes Around the World

by Kieran Berryman
a picture of the Earth

The following article exclusively cites the 2024 State of Global Air Report.


From vigilant mountain ranges to sweltering deserts, the Earth expresses itself across a diverse range of environments. Humans live in these varied environments and experience the differences between them. From temperature and weather to cultural or political differences, these regions couldn’t be more dissimilar. Air quality, or perhaps it would be better to say air pollution, is not different. As you look at the regions across the globe, you’ll be able to see the differences in air pollution.


The State of Global Air report separates these regions into seven different classes along geographic and economic lines. Those classifications are as follows:


  • Central Europe, Eastern Europe, and Central Asia.

  • Eastern, Western, Central, and Southern Africa.

  • Latin America and the Caribbean.

  • North Africa and the Middle East.

  • South Asia.

  • Southeast Asia, East Asia, and Oceania.

  • High-Income Countries (The United States, Canada, Australia, Chile, Argentina, Uruguay, and most of Western Europe).


While most of these “Super Regions” follow geographic patterns, the high-income classification does not. This is because the groups are based on “similar cause-of-death patterns.” 


But why do these regions have different causes of death?

 

 

Why Is Air Quality Not Uniform?

Despite what was suggested above, air quality and air pollution are not the same thing. Air quality is a measure of how clean or dirty the air is, to put it simply. Air pollution, on the other hand, determines that measure. So the reason that air quality isn’t uniform across the globe is that air pollution isn’t uniform. But why is that?


Well, air pollution isn’t just one thing. It’s a term for a bunch of different things that exist in the air. We call these different things air pollutants. These pollutants come from various sources that can exist in one area, but maybe not another. The distribution of pollutant sources is the basis for the differentiation in air quality worldwide. If a source in North America produces pollutant A, for example, and that source only exists there, then only North America will be affected. They will experience high levels of pollutant A while the other regions will not. The Global Air Report primarily discusses three common air pollutants: PM2.5, NO2, and Ozone.

Particulate Matter (PM)

Particulate matter is a term used to describe all of the little tiny particles that float around in the air. These particles are generally sorted into three size categories: PM1, PM2.5, and PM10. These categories are based on the particles’ diameter in micrometers. The Global Air Report focuses on PM2.5 because it has been found to have numerous adverse health effects. Notably, the report states that “PM2.5 is the most consistent and accurate predictor of poor health outcomes across populations.” 


Particulate matter has a high number of sources, including “residential fuel use, energy generation, industries, transportation, agriculture, windblown dust, waste combustion, and construction activities.”

Nitrogen Dioxide (NO2)

Nitrogen dioxide is a pungent gas that has been linked to a number of adverse health effects, including “asthma and other respiratory diseases.” Additionally, NO2 reacts with substances in the air and can create other pollutants, such as the other two in this article: particulate matter and ozone. Because of this, NO2 necessitates significant consideration.


Nitrogen Dioxide is primarily created as a byproduct of fuel combustion. Because of this, it has similar sources to PM, including “vehicles, power plants, and industrial facilities.”

Ozone

Ozone, or ground-level ozone, is a gas that is harmful to human health and adversely affects plant life. It is estimated that Ozone levels have risen by 30% to 70% in the last 100 years. This is because human activities have heavily exacerbated the creation of ground-level Ozone. Ozone isn’t released directly into the air; instead, it is created through the reaction of other air pollutants.


As human activities like the “burning of fossil fuels in vehicles, power plants, factories, and homes, and through industrial activities” have ramped up in recent years, so has the creation of ground-level Ozone.

 

 

Because these air pollutants are produced by different sources (for the most part), it makes sense that they would be found in different areas of the world. Now, most air pollutants exist everywhere on Earth. But where is getting hit the hardest?


  • Particulate Matter: In 2020, the highest average PM2.5 levels were seen in South Asia; Eastern, Western, Central, and Southern Africa; North Africa; and the Middle East.

  • Nitrogen Dioxide: In 2020, the highest average NO2 levels were seen in North Africa and the Middle East, high-income countries, and Central and Eastern Europe and Central Asia. This is because NO2 production can be heavily centered around urban centers, particularly where there is a lot of automobile traffic. 

  • Ozone: In 2020, the highest average Ozone concentrations were found in the Middle East, South Asia, and East Asia. Notably, various small tropical island nations experienced the least amount of Ozone exposure.



To recap, air quality isn’t the same around the world, just as it isn’t the same in your kitchen, as it is, say, in your bedroom. Different pollutant sources found across the globe affect air quality in the regions where they can be found, imbalancing the air everywhere.

 

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