Pollution and Aviation- Beyond CO2

It is no secret that the aviation industry emits copious amounts of carbon dioxide (CO2) into the atmosphere. While CO2 is responsible for about 3/4th of global emissions and is a primary greenhouse gas causing atmospheric warming otherwise known as climate change, it is not the only environmentally damaging pollutant emitted from air travel.

Pollutants are classified as either primary or secondary. CO2 is a primary pollutant, as it comes directly from a source such as burning fuel. A secondary pollutant, however, is a pollutant that forms in the atmosphere when a primary pollutant reacts with other molecules. Tropospheric ozone, acid rain, and nitrogen dioxide (NO2) are some examples of these. Not only are these pollutants bad for your health, contributing to higher rates of respiratory and heart conditions, they also adversely affect the environment and contribute to climate change. While CO2 emissions tend to dominate the discussion around climate change, it is important to remember that the burning of fossil fuels releases other dangerous pollutants in addition to CO2. This article will highlight what these other pollutants are and what are consequences of emitting them in large quantities.

When we hop on a plane to fly across the country, how much and which primary pollutants are being emitted into the atmosphere? What secondary pollutants are produced as a result of this, and what are the potential health and environmental consequences of pollutants associated with air travel?

I recently bought a plane ticket to fly from Seattle to Paris. While my first concern was cost and finding an airline that has implemented strict safety regulations for COVID-era flights, my next thought was, “How much CO2 is this flight going to produce?” While maybe not everyone is concerned with carbon counting, it is a growing factor, especially among millennials, contributing to our transportation decisions. According to the International Civil Aviation Organization’s Carbon Calculator, my trip will emit about 3,860 pounds, or 1.8 metric tons of carbon dioxide. To put this in perspective, I would have to drive 15,930 miles in a passenger car (getting 22.3 mpg) to emit an equivalent amount of CO2.

As stated previously, CO2 is not the only dangerous pollutant emitted from air travel. Nitrogen oxides (NOX) and particulate matter (PM) are also among some of the potentially harmful pollutants that are important to consider when analyzing the detrimental effects of air pollution on the health of people and the planet. NOX are produced through the burning of fossil fuels and once in the atmosphere, the Nitrogen monoxide (NO) oxidizes into Nitrogen dioxide (NO2), making it a secondary pollutant. Regarding its effects on human health, high levels of NO2 have been correlated to detrimental outcomes like lung inflammation. Furthermore, NO2 contributes to increased levels of ground-level ozone. While stratospheric ozone helps protect the planet from ultraviolet light, ground-level ozone when breathed can inflame the linings of the lungs and cause reduced lung function, bronchitis, emphysema and asthma.

According to the Federal Aviation Administration, aviation emissions can be broken down approximately as “70 percent CO2, a little less than 30 percent H2O, and less than 1 percent each of NOx, CO, SOx, VOC, particulates, and other trace components including HAPs (hazardous air pollutants).” While the figure of less than 1% of NOx might seem insignificant, considering its harmful effects to the respiratory system, it is safe to say that any amount of NOx anthropogenically emit into the atmosphere is potentially harmful to human respiratory health, especially when considering that underlying respiratory illnesses can increase a person’s chance of contracting the COVID-19 virus.

Particulate matter (PM) results when fuel combustion is incomplete, releasing solid or liquid particulates into the air. Because of their miniscule size, these particulates can be inhaled deep into the respiratory system and even enter the blood stream. According to the Environmental Protection Agency, these particulates are damaging to human health and have been linked to asthma, heart attacks, reduced lung function, inflammation of the respiratory system, irregular heartbeat, and even premature death in people with underlying health conditions. Have you noticed how high levels of pollution reduce visibility significantly? This is largely the cause of particulate matter in the atmosphere, you might know it colloquially as smog. Furthermore, when particles settle, they can acidify waterways, alter nutrient balances off the coast and in rivers, deplete soil nutrients, and contribute to acid rain. Much like NOx, while particulate matter may only make up around 1% of aviation emissions, their harmful effects to the human and ecological life should be of significant concern to the aviation industry.
In summary, CO2 should not be the only focus of the aviation industry’s emission reduction strategies. By highlighting the detrimental effects of some of the other primary and secondary pollutant emit during air travel, I hope to increase awareness to the importance of reducing emissions in the aviation industry. With the growing urgency to address the climate crisis, it is no longer morally responsible or economically smart for aviation companies to neglect implementing emissions reduction strategies. If 2020 has taught us anything, it’s that decades of unrestricted pollution and ecological destruction has come back to haunt us. The time for aviation companies to prioritize emissions reduction is now, the people and the planet cannot wait any longer.

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Hailey LaJoie

Special Projects Manager 

eTT Aviation


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