Air Pollution, The World’s Largest Environmental Health Threat

Naila Moloo
11 min readDec 20, 2021


Ella Kissi-Debrah died when she was only 9 years old due to air pollution in 2013. Ella lived within 30 metres of London’s South Circular road and unfortunately, due to traffic emissions, the air she breathed everyday included an abnormally high level of pollutants. In the region of London that she lived in, Lewisham, she was exposed to high levels of nitrogen dioxide emissions and particulate matter. Sadly, Ella is one of the 600,000 children who die from acute respiratory infections caused by polluted air every year.

Particles and gases suspending themselves in the atmosphere are making their way into humans’ bodies more and more, prematurely killing 7 million people annually. The term ‘air pollution’ refers to harmful substances surrounding us that cause damage to organisms and nature. Common pollutants include nitrogen dioxide, carbon dioxide, sulphur dioxide, ozone, and fine particulate matter, and although these have always been problematic, their ramifications are worsening and affecting humans much more severely than previously predicted.

Air pollution is a vast problem, and it’s going to require a solution at the same scale.

In this article we’ll cover:

1. How air pollution affects humans

1.1 Health effects

1.2 Effects on different age groups

1.3 Effects on developing countries

2. How air pollution affects the planet

2.1 The two ozones

2.2 Effects on ecosystems

3. Why air pollution happens

3.1 Fossil Fuels and Vehicle Exhaust

3.2 Natural causes

3.3 Agriculture

4. What we can be doing

4.1 Individual

4.2 Organizational

1. How Air Pollution Affects Humans

1.1 Health Effects

We are affected by air pollution from a young age. Dangerous changes in blood pressure can lead to risks for pregnant women, and airborne toxic substances have been found to increase the risk of breast cancer, lung cancer, heart disease, and strokes. New diseases are even beginning to surface, like the Beijing cough, a dry hack accompanied by an itchy throat due to air pollution.

If we’re covering air pollution, we have to talk about fine particles, the most dangerous pollutants because of how easily they can slip into the human body. These are called particulate matter (PM), composed of chemicals like sulfates, carbon, and nitrates. Emissions from combustion, wildfires, burning matter, etc, all contain PM. There are two main groups of these microparticles, PM 2.5s and PM 10s. PM 2.5s are particles less than 2.5 microns in diameter (30 times thinner than a human hair). These microparticles are the deadliest and account for most impacts on health concerning air pollution. PM 10s, on the other hand, are less than 10 microns in diameter and mainly include dust, pollen, and mould. Outlined in the WHO’s latest climate report, both groups’ recommended exposure limits have been decreased, PM 2.5s by 50% and PM 10s by 25%.

Air pollution as a whole is bad news. Besides health implications, extreme weather is causing an increase in the production of allergenic air pollutants like mold and pollen. This crisis impacts everything we rely on, from our crops to biodiversity to water supply. Breathing in air pollution takes away at least 1–2 years of a typical human life, but it’s worse for certain groups.

1.2 Effects on Different Age Groups

Air pollution most severely affects children because they are in the developmental stage of their life and their airways are smaller hence they breathe more rapidly than adults. 80% of their air sacs called alveoli develop after birth which are responsible for transferring oxygen to blood, so if alveoli growth is altered this can become quickly problematic. This also applies to babies in the womb where premature birth and irregularly low birth weight have been going up over the years. Risks for preterm birth are increased even when women are exposed to low levels of particle pollution, and when exposed to pollution spikes there is a simultaneous spike in preterm birth. The quality of air that we breathe is not only diminished when outside, but also in the car.

In addition, children are closer to the ground than adults since they are shorter, consequently bringing them closer to the level of vehicle exhaust pipes and cigarettes. The fact that children are generally outdoors playing for long periods of time paired with their not fully evolved defense systems against infections is contributing to sky rocketing respiratory infections.

1.3 Effects on Developing Countries

Another group that faces the worst effects of air pollution is developing countries, as they often lack the technology, infrastructure, and resources to be able to fight air pollution. Energy production in developing countries, which we have already established as a leading cause of pollution, mainly comes from resources like coal. China on its own accounts for over 50% of the world share of coal, consuming 4,319,921,826 tons every year. Developing countries have developing economies, meaning they are less likely to have the capability or money to invest in clean energy and alternative technologies.

Most deaths that stem from air pollution occur in developing countries, seeing as the poorest people live in cramped cities heavily exposed to toxic pollutants. When they get sick, it’s much more difficult to get treatment. Low indoor air quality is also increased because of burning wood and kerosene for uses such as cooking in homes.

In India, air pollution is known as the fifth largest killer. The capital of the country, Delhi, is the most polluted city in the world. November 8, 2017, marked the day when the Air Quality Index crossed the pollution levels of 999. For context, the safe limit marked by the WHO for the Air Quality Index is 100 — meaning that the city passed the limit by more than 10x. This alarming level of air pollution is credited to vehicular emissions (41 per cent), dust (21.5 per cent), and industries (18 per cent). Those in the Delhi population show 1.7 times higher susceptibility to breathing issues than those in rural areas.

2. How Air Pollution Affects the Planet

2.1 The Two Ozones

Sometimes when we hear about ozone, it can get confusing. The ozone layer is necessary for survival, but ozone is also a pollutant? How does that work? It all has to do with placement.

Ozone can be beneficial or detrimental, depending on its location. Made up of oxygen, ozone is found in the upper atmosphere and at ground level. The upper atmosphere is where stratospheric ozone occurs, forming a protective layer that blocks humans from harmful UV radiation. We know it as the ozone layer, which we need to survive but are destroying because of activities discussed previously, like industrial emissions. This layer is correlated with skin cancer rates going up, food chain disruption, weakened immune systems, a diminish in crop yield, and the list goes on and on. This all goes to say: without the ozone layer, life will cease to exist. That’s not ideal.

The destruction of the ozone layer is creating a hole that is currently bigger than Antarctica. Chlorofluorocarbons (CFCs), chemicals used in refrigeration systems and that used to be deployed as propellants in aerosol spray cans, have been acknowledged as the biggest contributor to ozone layer degradation. Such chemicals travel to the stratosphere from Earth’s surface and then are broken down by UV radiation, hence demolishing ozone. Luckily, CFCs have been banned in 197 countries around the world, but the ozone layer will take another 50 years to fully heal.

On the other hand, ground-level ozone is a toxic pollutant that plays a primary role in smog. This is not directly emitted into the air but is instead produced through chemical reactions between volatile organic compounds and nitrogen oxides, which happens when pollutants react in the presence of sunlight. When spending time outdoors in the summer people are particularly affected because of the hot temperatures (and so is vegetation, especially dicot species like soybean and cedar). Breathing in ozone can cause chest pain, congestion, throat irritation, and severe damage to lungs. Ozone poisoning is a real thing, and it’s lethal.

2.2 Effects on Ecosystems

Air pollution causes atmospheric deposition of nitrogen and sulfur, which is a big stressor for ecosystems. The lack of sunlight visibility reduces growth in plants, acid rain can flow into streams and rivers, eutrophication of both terrestrial and aquatic ecosystems occur, and the living tissue in trees are directly damaged, preventing respiration and photosynthesis. Plants become more susceptible to disease and pests, and agricultural crop yields diminish. This of course influences animals in return who live in such habitats. One species known for being impacted by air pollution are birds, directly affecting their respiratory systems and indirectly affecting their food sources. Bird populations within North America have declined by nearly 3 billion since 1970, which is devastating.

Why Does It Happen?

3.1 Fossil Fuels and Vehicle Exhaust

Now that we know air pollution is a problem, why does it really happen, and what are the root causes? The primary cause is, not surprisingly, fossil fuel combustion. What’s powering our cars, electricity, and manufacturing capabilities is deteriorating the air we breathe in. Motor vehicle emissions are also up on the list with fossil fuels — they both release carbon dioxide, nitrogen oxides, sulfur oxides, and carbon monoxide, which are highly poisonous and reactive gases that contribute to the formation of smog and acid rain.

3.2 Natural Causes

Aside from industrial emissions, other sources include smoke from wildfires (which are mainly human-induced), methane from decomposing matter in soils, and gas from volcanic eruptions. Returning back to the source of wildfires, let’s take a quick look at the destruction it causes. We can break it down into steps and use the example of the dozens of wildfires burning in the West.

1. Climate change increases hot and dry weather that fuels wildfire. We won’t go through why climate change exists because it’s pretty much already been covered, and the answer is nearly always human activity.

2. Wildfires generate huge plumes of smoke, and when this smoke gets into higher levels of the atmosphere it is carried downstream.

3. When smoke is carried to the East Coast after wildfires occur in the West Coast, this results in several things: poor air quality, heat waves, and an abundant amount of particulate matter to be breathed in (we’ll cover this in the next part of this article). This isn’t great for humans, to put it lightly.

3.3 Agriculture

There’s also another notable emitter that ties in with all of this, and that’s the agriculture industry. Heavily fertilized fields and animal waste produces ammonia in a gaseous state, which enters the air and combines with combustion emissions. The result is the formation of deadly solid particles called aerosols. Aerosols alone cause over 3 million deaths every year, and half come from farming. Funnily enough, the main issue here isn’t the ammonia emissions. Increased atmospheric ammonia does not correlate with decreased air quality. The real problem lies in the emissions from combustion, and their ability to come together with ammonia; this is what is responsible for aerosols.

That means, if we were to look at the common denominator, we would find combustion. If we could cut down on combustion, most ammonia from farming would end up in the troposphere and the particulate matter would be trapped by raindrops and removed from the atmosphere. The answer is apparent, then, and that’s to stop using fossil fuels. If we could do this, direct consequences would be avoided but so would exacerbate repercussions like aerosol formation from agriculture. However, it’s of course not as simple as just saying we’ll stop using fossil fuels. To be able to substantially cut down on fossil fuels we need global transformation, and to do this, we need to re-shape policy and our current infrastructure.

4. What Can We Do?

4.1 Individual

There are a lot of things we can do to prevent air pollution, like reducing the number of trips you take in your car, not burning leaves and trash, reducing fireplace and wood stove use, etc, but many people hear these small actions and don’t do anything about it, which usually stems from the need for comfort and ease. If everyone was actively trying to reduce their carbon footprint, we would 100% see a change, but this is unfortunately not reality. One thing that we need to shift is the narrative around consumerism. In today’s society, consumerism looks great. Buying a big house, having a private island, owning three fancy cars, flying around on a private jet — this all sounds ideal. Carbon footprint wise, though, it’s not all that ideal. Decreasing the amount of things you are buying (and making sure the brands you are buying from are sustainable) can make more of a difference than you might think. On top of that we need to focus on emission offsetting, a method used to balance out and compensate personal emissions.

4.2 Organizational

On a larger scale, governments need to make climate a priority. In most cases, many governments are doing so, but how much of what they are claiming is actionable? Is their word being held accountable? Asking these questions and contacting your political leaders is important because investing in green technology will be key to a green future.


  • Air pollution is mainly caused by fossil fuel combustion, vehicle exhaust, and industrial emissions
  • Because of fertilizers and livestock waste, ammonia in a gaseous form is released into the atmosphere and combines with fossil fuel + vehicle emissions to form aerosols, particles that kill 3 million people yearly
  • Particulate matter, divided into PM 2.5s and PM 10s, is arguably the most dangerous type of pollution as it can get deep in your lungs and even your blood
  • Air pollution is destroying the ozone layer which shields us from harmful UV rays and currently has a hole the size of Antarctica due to human activity (releasing pollutants like ozone, particulate matter, nitrogen dioxide, etc)
  • Causes on the human body can be fatal, including lung cancer, respiratory disease, and strokes
  • Children are the most affected since they are in the developmental phase of their life
  • Developing countries are facing the worst implications of air pollution because of their reliance on fossil fuels
  • We each have a role to play, and a responsibility in this crisis!

Thank you so much for reading this! I’m a 15-year-old passionate about sustainability, and am the author of “Chronicles of Illusions: The Blue Wild”. If you want to see more of my work, connect with me on LinkedIn, Twitter, or subscribe to my monthly newsletter!