Across the world, there are many areas where the level of pollutants varies from moderately harmful to downright dangerous. This includes a number of major cities that struggle with air pollution problems linked to increased deaths. However, air pollution isn't just a problem in large cities, it can also affect rural areas and even individual households.
Some of the products that are used, for example, to treat wood, that are incorporated into paint, or that are used as fire retardants in furniture, can off-gas volatile organic compounds and carcinogens.
These are released into the air and can not just linger but accumulate inside homes and other buildings. Just living in a rural area surrounded by lush greenery does not necessarily guarantee that the air inside a home or workplace is safe and clean to breathe.
In order to understand some of the hidden dangers of air pollution, we also need to understand some of the causes of air pollution and just how dangerous it can be if not properly addressed.
What is air pollution?
When we hear the term air pollution, many people automatically think about major sources of pollution, like internal combustion engines and large industrial facilities. However, these pollution sources are only the most visible. We often don't realize that there are a lot of pollutants in the air that we cannot see the cause of, or are not aware of.
Air pollution can be thought of as simply any compound or element in the air that is harmful to humans.
In the US, the standards around air pollution are actually relatively new. It wasn't until 1970 that the National Ambient Air Quality Standards were established, and even then, air pollution was mainly understood as a threat to respiratory health.
It would take several decades for researchers to understand that increased air pollution can also impact many aspects of health. Today, we know that air pollution can contribute to cardiovascular disease, diabetes, obesity, and neurological and immune system problems.
On a technical level, most air pollution is associated with oxidative stress, an imbalance between free radicals and antioxidants which can lead to cell and tissue damage. The WHO officially classified air pollution as a human carcinogen in 2013, due to its contribution to oxidative stress, among other conditions.
As you can likely tell based on how recently standards have been developed for air pollution levels, our understanding of just how harmful it can be is relatively new. In many cases, scientists are still learning about the potentially harmful aspects of different types of air pollution, as well as its effects on the environment.
It's important to note at this point, however, that air pollution doesn't inherently mean pollution produced by human action. Volcanoes and other natural processes can also heavily pollute the air with particulates and volatile compounds that can be harmful. However, most types of naturally-occurring pollution are localized and dissipate relatively quickly, whereas pollution produced by humans has reached such high levels in the atmosphere that it does not dissipate greatly over time.
Essentially any product or process that produces excess gasses or particulates can cause pollution.
Now that we've discussed a general perspective of air pollution, let's talk about some of the technical aspects of major pollutants found in the world around us.
Traffic-related air pollution, referred to as TRAP, is made up of emissions from motor vehicles. Most of us are likely to recognize this form of air pollution, which can lead to very visible smog and haze, but it is actually not one single pollutant, but rather a cocktail of compounds. TRAP generally contains carbon, nitrogen oxides, volatile organic compounds (VOCs), sulfur oxides, ground-level ozone, aromatic hydrocarbons, and particulate matter.
Many of these compounds will not mean much to the average person, but perhaps the best way to think of these pollutants is as regularly occurring compounds that can be dangerous in moderate to high concentrations. A few VOCs and some ozone may not kill you. But they cause damage to your cells, which builds up over time, to the point where the damage can be difficult for the body to repair.
Ozone is another big pollutant and is toxic even in small amounts. This gas occurs naturally in the upper atmosphere, where it offers protection from the Sun's ultraviolet radiation.
Ozone is created when sunlight splits apart O2 into single atoms, which can then join with O2 molecules to make ozone (O3).
Lower down, in the troposphere, ozone can be created by automobile exhaust and industrial emissions, which release nitrogen oxide gases (NOx) and volatile organic compounds as by-products of burning gasoline and coal. NOx and VOC then combine with oxygen to form ozone during sunny, hot periods.
Noxious gases are a group of pollutants made up of carbon dioxide, carbon monoxide, sulfur oxides, and nitrous oxides. These gasses are generally a byproduct of combustion. These oxide rich compounds cause harmful reactions in our cells, which over time can cause a variety of conditions.
Particulate matter, or PM, is generally made up of particles that are less than 10 micrometers in size. These particles can include chemical compounds such as nitrates or sulfates or can be made up of dust from machinery or even naturally-occurring dust storms. Cigarette smoke and other forms of incomplete combustion create an excess of particulate matter. These particles can go deep into the lungs and enter the bloodstream, causing damage to several organs.
Volatile organic compounds, or VOCs, are carbon-containing compounds that have a high vapor pressure at ordinary room temperatures. VOCs are common in all sorts of household chemicals and products and are given off by paints, cleaning supplies, pesticides, fire retardants, glues, and more. When we say that a new car has, "a new car smell," that is likely VOCs you are smelling, and these can actually be quite harmful to your health.
The last main pollutant we'll cover is polycyclic aromatic hydrocarbons or PAH. These compounds contain both carbon and hydrogen, hence the term 'hydrocarbon', and many occur naturally in coal, crude oil, and gasoline, among other sources. There are roughly 100 naturally-occurring PAHs in the environment, and about 15 of these are known carcinogens. Many manufacturing and power generation processes produce PAHs.
What causes air pollution?
We've already discussed many of the causes of air pollution, like manufacturing and combustion engines, but let's spend some more time on the topic. Air pollutants, primarily the types mentioned in the previous section, are produced through virtually every modern chemical-based process to some degree.
Here's an exercise to help you understand this better. In your house, think about all the things that use energy. For example, lights, refrigerator/freezer, computer, lawnmower, vehicles, heating system, air conditioning, etc. Most of the energy needed to power all of this is created using processes that transform harmless chemicals into harmful ones.
Electricity can cause ozone creation in the air by reaction with oxygen molecules. Exhaust from the burning of fossil fuels can create particulate matter or VOCs. The burning of gas for heat can create hydrocarbons and VOCs. Even cleaning up is not safe. Using cleaning supplies can remove compounds from surfaces, but this is done through chemical reactions that can create pollutants.
Our modern world uses a lot of energy, and creating this energy inevitably causes pollution. While types of pollution naturally occur, the very high levels we are seeing now are down to the mismanagement or overproduction of human activities.
Air pollution is a necessary bi-product of life on Earth, and there are natural systems that break down these compounds or wash them out of the air. But scientists believe the very high levels of air pollution created through human activity and the burning of fossil fuels, are too high to be removed easily by these processes and are building up.
The last thing to highlight is the air pollution inside our homes and buildings. It's important we maintain good ventilation in enclosed spaces, in order to ensure there isn't a buildup of any harmful volatile compounds off-gassing from furniture, paints, or cleaning materials.
If indoor space is too airtight, it could fill with VOCs, particulate matter, and hydrocarbons. New products give off higher levels of these gases than older products because, over time, the volatile gasses dissipate.
Researchers are developing new compounds to use in paints, furniture, and even industrial products that do the same job, such as providing fire retardation, but without off-gassing harmful chemicals. These green products are becoming more common, and it may make sense to use more of them, especially for those who are concerned about levels of air pollution.
How to reduce air pollution
Now that you've read through all of this, you might be trying to think of ways to reduce the air pollution you are exposed to or are responsible for. Below, I'll lay out a few different ways you can do this, but keep in mind that the list isn't exhaustive, and reducing air pollution is more of a mentality than it is a straightforward list of steps.
To reduce air pollution you can:
- Conserve energy
- Limit driving
- Fly less
- Use electric equipment in place of combustion-powered equipment
- Use natural-based cleaners
- Use water-based or solvent-free paints
- Purchase used furniture
- Seal containers of cleaners tightly
- `Use energy-saving appliances
- Advocate for better energy production and manufacturing processes
- Choose "green" energy suppliers where available
Many of the things mentioned will both improve the air quality in your house or locally, and also improve overall emissions. However, in many cases, they just offset air pollution from power plants and manufacturing plants. This is important to keep in mind, as reducing air pollution in the world is going to take a concerted effort from everyone..