Air quality in Tennessee

Is Tennessee a polluted state?

Tennessee is an American state located in the Southeastern region of the country. It is bordered by eight other states, which include among them ones such as Kentucky, Alabama, Mississippi and Arkansas. It has several prominent geographic features within its limits, with the Appalachian Mountains standing on the eastern side as well as the Mississippi River forming part of its western border. It is counted as the 16^th most populous out of all states in America, and is home to over 6.88 million people, a sizeable number that along with certain industries, can see a degradation in the level of air quality present throughout the state, which will be explored in further detail.

In 2020, several of its cities came in with some fairly high readings of PM2.5, indicating that the air quality throughout the state could do much to improve (although there were many cities that also came in with considerable better levels of air quality). PM2.5 refers to particulate matter that is 2.5 micrometers or less in diameter, on occasion going down to sizes as small as 0.001 microns and beyond. This incredibly small size makes it extremely dangerous to human health when respired, and as such it is utilized as a major component in the calculation of the overall AQI, or air quality index, among other pollutants.

The city of Red Bank came in with a PM2.5 reading of 12.2 μg/m³ over the course of 2020, as its yearly average. This reading placed it within the ‘moderate’ pollution ratings bracket, which requires a PM2.5 reading of anywhere between 12.1 to 35.4 μg/m³ to be classified as such. This placed Red Bank in 1^st place out of all cities ranked in Tennessee, as well as 1808^th place out of all cities ranked worldwide. This is a very high ranking for a U.S city amongst the world circuit, and is indicative that this city needs to take many steps to reduce its pollution levels.

However, it was the only city in the state to come in with moderate pollution reading over the course of 2020. Three other cities came in with a ‘good’ pollution reading (10 to 12 μg/m³ required), whilst the remaining thirteen cities came in within the World Health Organizations (WHO's) target bracket of 10 μg/m³ or less, showing that there are certain pollution hotspots occurring within Tennessee, particularly during certain times of the year, and as such, caution should be practiced during these particular periods of higher pollution levels.

What causes air pollution in Tennessee?

Tennessee has many different sources, or cause of air pollution occurring throughout the course of the year, with some months bringing higher readings of both PM2.5 and PM10 (as well as other air contaminants) due to reasons pertaining to both meteorological and anthropogenic activity, although the latter will typically dominate the reasons behind air pollution for the entirety of the year.

Many, if not all of these pollution sources typically come from combustion sites, and to mention one of the more prominent ones, would be that of vehicular emissions. This is a problem that is not just localized to Tennessee, but rather the entirety of the United States and indeed the whole world. With increasing vehicle ownership, coupled with growing population sizes, vehicles are responsible for putting out large amounts of air pollution throughout the year.

All manner of personal vehicles such as cars and motorbikes will be inhabiting the roads in the hundreds of thousands, at any given time, and to compound this issue further, the use of heavy duty vehicles such as lorries and trucks can drive up pollution levels even higher. Although it has a diversified economy, Tennessee still deals in the extraction and exportation of many products such as gravel, sand, marble and other mineral based products such as ball clay.

As a result, there would be a need for largescale use of these heavy duty transportation vehicles to move these items out of the state for both domestic and international exportation (not to mention the numerous items such as foods or other necessity products being imported), which in turn would lead to many trucks and lorries on the road.

These often run on diesel fuels, and can put out far larger quantities of chemical pollutants and hazardous particulate matter than a smaller or non fossil fuel using counterpart would. Thousands of tons of microscopic rubber particles are also released into the environment from subsequent wearing down of tire treads as well, showing that it is not just the vehicles exhaust fumes that contribute to environmental pollution.

Other significant sources of air pollution would be ones such as emissions from factories and power plants, which often utilize other fossil fuels such as natural gas or coal to provide their energy, along with mining sites (which are known to have caused large amounts of environmental damage in Tennessee), construction sites, road repairs and even demolition areas. All of these can put out large amounts of dangerous particulate matter into the air, particularly when construction site maintenance is not fully taken care of (with piles of uncovered sand or construction dust accumulations all leading to PM2.5 and PM10 particles escaping into the atmosphere). Occasional forest fires can also be a source of pollution in the state as well, showing the extremely wide variety of various polluting sources present in Tennessee.

When is the air quality at its worst in Tennessee?

Observing the data gathered over the course of 2020, it appears that there are certain lengths of time in which the air quality was shown to be at its worst, with higher readings of PM2.5 present in the air. To use the first six cities ranked according to their air pollution averages over 2020, it can be seen that the later months of the year are when the PM2.5 levels go up by quite a significant amount. Although the more polluted cities such as Red Bank showed sporadic spikes in pollution levels throughout many months of the year, it still had its highest reading taken in December, which was in fact the month in which pollution was at its absolute highest throughout the state.

To cite some examples, Red Bank presented with a reading of 16.1 μg/m³ in December, and the city of Goodlettsville also presented with a reading of 14.7 μg/m³ in December, once again the highest of the year. Chattanooga came in at 14.8 μg/m³ in December, whilst the cities of Farragut, Hendersonville and Knoxville all came in with PM2.5 readings of 14.5 μg/m³, 17.1 μg/m³ and 21.9 μg/m³ respectively in the final month of the year.

Whilst there were a few minor exceptions to this, such as the city of Memphis having its highest period of pollution in the middle of the year instead of at the end, it stands to reason that December was unanimously the most polluted month of the year, and could perhaps correlate with the drop in temperature leading to a higher demand for electricity to provide heating to both homes and businesses. The most polluted month on record for Tennessee was the previously mentioned 21.9 μg/m³, as taken in December in Knoxville, indicating that the air would be at its most full of smoke, haze and other contaminating agents.

Who are the most at risk from polluted air in Tennessee?

In regards to keeping oneself safe from the damaging effects of pollution, it is important to note that no portion of the population is truly immune to the damaging effects that air pollution can bring, with even healthy young adults succumbing to health issues if exposure to pollution is excessive. However, there are certain groups that are even more at risk of pollution exposure.

These include groups such as young children, pregnant mothers, the elderly, those with compromised immune systems, preexisting health conditions or just general poor health (such as those with sedentary lifestyles, heavy smokers or a combination of both), as well as those with a hypersensitivity towards chemical pollutants, which is becoming more and more common due to many people having been exposed to harmful chemical pollutants over the course of their lifetime and thus developing allergies or sensitivities to these air contaminants. These are the groups that should take extra care to reduce their exposure whenever possible.

What are the main types of pollution in Tennessee?

With much of its pollution arising from the various combustion sources taking place across the state, with vehicle engines and factory or power plant boilers putting out their polluting effluence, there would subsequently be a predictable number of main pollutants in the air, as is typically seen throughout the world (with differences occurring due to certain countries having more lax standards on fuel quality, as well as allowing extremely poor practices such as plastic or synthetic waste material to be openly burnt).

The main ones released from vehicles would be chemicals such as carbon monoxide (CO), carbon dioxide (CO₂), nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). These last two are particularly notorious offenders when it comes to vehicular emissions, and both of them can be extremely damaging to both the environment as well as human health, causing instances of acid rain to occur, as well as causing irritation and inflammation of the airways and lung tissues, triggering off conditions such as asthma or other respiratory ailments.

The various oxides of nitrogen (NOx) released from vehicles and other combustion sites, as well as certain gases and other pollutants, can be converted into one of the more prominent pollutants that is seen across America, ozone (O₃), or smog as it is better known when it is found in large accumulations. This is created via exposure to solar radiation from sunlight, and typically sees larger occurrences during the summer months.

Other prominent pollutants include ones such as black carbon and volatile organic compounds (VOC's), both of which find their release from the incomplete combustion of fossil fuels and organic matter. Some examples of VOC's include chemicals such as methylene chloride, benzene, toluene, xylene and formaldehyde.