While many view climate change, biodiversity loss, and pollution as 3 distinct yet interconnected parts of the environmental crisis, we decided to split pollution within the first 2 sub-crises. Seeing that pollution usually forces one of climate change or biodiversity loss, it seems redundant to consider it separately. Nonetheless, we’ll quickly review pollution here to understand how different types of waste infiltrate and damage the environment.

In general, pollution occurs when elements or compounds [or anything else they form] that harm the environment are released. These chemicals can be emitted as solids, liquids, or gases, but what do they actually do? How are they harmful to nature and to us?

Well, that depends on the type of pollutant, the environment’s characteristics, and how both react with one another.


When pollution is emitted in the natural environment, it becomes a part of the ecosystem, even if just momentarily. Solids can degrade into the soil or ocean, liquids can seep into the ground and mix with other liquids, and gases can be powerful GHGs or react with other elements to form secondary pollutants.


Some gases emitted into the environment are primary emitters, which is probably what most of us think of when we mention gas emissions. However, other types of polluting gases exist – and are classified as secondary emitters. They may not be harmful as emitted, but they can still end up creating extremely polluting gases. For example, NOx [nitrogen oxides] gases and VOCs [volatile organic compounds] can react with one another to form ground level ozone. And although the ozone layer is essential to protect us from UV radiation, ground level [tropospheric] ozone is a completely different thing. It can cause serious health issues, large quantities of smog, and contributes to global warming.

Gaseous pollutant emissions can cause loads of problems since we end up breathing them in. That’s no secret. We should all know by now that polluted air can deteriorate human health through a variety of diseases and illnesses [e.g. lung cancer]. Unfortunately, these types of emissions are also quite concerning because of their global warming potentials [GWPs – or ‘greenhousiness’], which we hope you’re familiar with by now.

Air pollution [indoor and outdoor] is responsible for roughly 7 million deaths every year. That’s equivalent to 12% of the total 57.26 million deaths [yearly average from 2015-2020] recorded across the globe annually. That high percentage makes sense given that 91% of the global population lives in areas where the air quality is above WHO [World Health Organization] guideline limits.

It’s also important to note that gaseous pollutants aren’t all equal, as far as their greenhousiness goes. As we’ve seen in many sections, gases like methane can be much more potent than CO2. So far we have presented methane emissions as 28 times more potent than CO2 emissions over 100 years, but that doesn’t tell the whole story.

Methane actually doesn’t stay in the atmosphere for that long before being destroyed through natural processes [roughly 12.4 years]. However, it is a very potent GHG until then – which means it can cause significant warming in the first couple of decades after its release compared to CO2. In fact, it’s estimated that the greenhousiness of methane over 20 years is close to 84 [i.e. 84 times more greenhousy than CO2 over 20 years]. Therefore, reducing our methane emissions can play a vital role in curbing global warming as soon as possible.


For solids, the effects of pollution vary. Solids can pose significant problems to wildlife if mistaken for food [e.g. turtles choking on plastic bags]. As the solids decompose into various toxic compounds, they end up polluting soils and aquifers – eventually damaging ecosystems and inducing biodiversity loss. They can also break down into smaller solids, as some pollutants create micro-particles that are proving difficult to detect and filter.

As we’ve seen with micro-plastics in the ocean, microscopic waste particles can have devastating impacts on the environment – or even make their way up the food chain and into our bellies. Some of the micro-particles are so lightweight that they’re actually transported by gases and float around in our atmosphere. Unfortunately, this particulate matter can cause many health issues for all kinds of species when breathed in, including humans.


Like solids that have broken down, liquid pollutants can travel in water bodies and seep into soils – damaging ecosystems along the way [e.g. contaminating a water table]. Every day, factories legally discharge tonnes of contaminants into rivers and lakes, in the hope that the water body will help the pollutant decay or settle within a certain period of time. Unfortunately, this obviously threatens marine and coastal ecosystems through toxic pollution and/or eutrophication.

Humans and Cities

When it comes to humans, pollution affects us differently depending on where we live. Let a sausage represent a random item that is produced in the world.

There are populations in underdeveloped countries who see how the sausage gets made. Note that producing the sausage always has impacts on the environment. At the other end of the spectrum, there are the populations of developed countries that purchase and use the finished sausage. The finished sausage may or may not pollute while in use.

When disposed of, the sausage either returns to pollute underdeveloped countries – or ends up polluting less in a developed country’s waste management system, where sausage disposal is more advanced.

Those who witness the sausage making/disposal may live next to [or work in] lithium mines, clothing factories, or e-waste disposal sites. These people are living in environments saturated with air, water, and soil pollution. Only far away from the sausage factory/disposal site does the air quality begin to improve. Unfortunately, those closest to the sausage factory likely don’t have high-quality water purifying systems in place, so they get to drink polluted freshwater – on top of breathing polluted air.

The finished sausage users are luckier for the most part. With advanced water management systems, their freshwater supply is purified and seemingly endless, for now. As far as air pollution however, large city populations are at risk for some of the same health issues as the sausage factory workers – even in the most developed countries in the world. In fact, urban emissions from all sorts of sausages [e.g. combustion vehicles] can increase urban smog, particulate matter, and toxic pollution levels.

Some areas of the world experience such high levels of constant pollution that it’s visible to the naked eye. In fact, highly populated developing cities in Asia often have such poor air quality that even sunlight has a tough time penetrating the clouds of pollution [i.e. global dimming]. Individuals living in these cities have increased chances of dying prematurely every time they step out of their home.

It’s important to note that there are other, less obvious forms of pollution. Particularly, noise and light pollution are inducing biodiversity loss by disrupting many species’ instincts around mating, hunting, and surviving. While loud noises and artificial lighting are usually associated with urban areas, they’re becoming increasingly common in natural areas as well – due to encroaching human activities.