Pennsylvania is a state located within the Mid-Atlantic, or Northeastern region of the U.S.A. It is surrounded by other states such as Maryland, Ohio, New York and the province of Ontario to the northwest, showing its close proximity to Canada. With over 12.8 million people living in Pennsylvania, it is counted as the fifth most populous state in the entire country, and has a significant presence in various sectors such as steel production, paints and other household materials, as well as food products, with a sizeable agricultural industry to back this up.
With such a large amount of different industrial activities occurring, as well as a significant anthropogenic movement taking place on a daily basis, the air quality is subsequently affected by a wide array of sources, all of which compound each other to create elevated levels of pollution seen in Pennsylvania, pushing it to near the top out of all the most polluted states found in America.
To use some of its more polluted cities as an example, the city of Boiling Springs came in with a PM2.5 reading of 12.9 μg/m³ as its yearly average over the course of 2020. This placed the city within the ‘moderate’ ratings bracket, which requires a PM2.5 reading of anywhere between 12.1 to 35.4 μg/m³ to be classified as such. This is a high reading for a city in the United States, coming in at 266th place countrywide, as well as 1678th place worldwide, giving it a poor ranking in terms of its air quality. Other cities in Pennsylvania that came in with equally high readings were one such as Bethlehem at 12 μg/m³, Emmaus at 11.9 μg/m³ and Bakerstown at 11.7 μg/m³.
The state had one of its cities come in at the moderate rating of air pollution, and eleven come in with a good pollution rating (10 to 12 μg/m³ required), which indicates that there is much that could be done to improve the quality of its air, thus improving living conditions for its citizens, particularly in regards to reducing illnesses and other pollution related issues. Whilst there were many cities that came in with more appreciable qualities of air, typically falling within the World Health Organizations (WHO's) target goal of 10 μg/m³ or less (with 40 cities coming in with this rating in 2020), the fact that there are still many cities coming in with higher levels of pollution shows that many of its inhabitants would be at risk to pollution related health problems.
In Pennsylvania, there are numerous different causes of air pollution, all of them coming together to form the compounded levels of air contaminants seen. To look at some of the more salient causes of pollution, they would be ones such as the ever-present emissions and exhaust fumes that come from vehicles. With over 12.8 million people living in the state, at any given time there would be huge numbers of cars and motorbikes inhabiting the road, all of which would be giving off large amounts of chemical compounds, related to the combustion of their fuel, as well as hazardous particulate matter.
Both of these can cause irritation to the respiratory tract and lung tissue, as well as having carcinogenic effects on those who are subject to excessive exposure (such as those who live near industrial areas or by busy roads).
Besides the regular use of cars and other smaller personal vehicles, there is also the issue of heavier duty vehicles, which include among them ones such as buses, trucks and lorries. These often run on fossil fuels such as diesel, and can put out far more pollution than a singular vehicle of a smaller size would. In cities that see a high amount of import or export taking place, these would be a common sight on the road, and as such would bring their own addition to the overall pollution level.
Other significant sources of pollution found throughout the state would be ones such as factory emissions, as well as pollution given off by other related industrial areas or power plants. These facilities often utilize their own fossil fuels such as coal, which can also lead to large scale release of further pollution when it is combusted to provide energy. Furthermore, during colder months, the changes in weather can lead to larger energy consumption due to both homes and businesses requiring more electricity in order to provide heating. This in turn leads to greater consumption of coal in power plants and thus more pollution being released.
Other causes would be ones such as road repairs, construction sites, and even the creation of unique pollutants during the summer months when various chemical compounds are exposed to higher levels of sunlight, thus creating novel compounds that can decrease the air quality. Shale gas wells are also known to have been a cause of some deaths and health issues related to the inhalation of particulate matter, which is released in large amounts from these sites, and other similar ones that involve the extraction of materials or disruption of large amounts of earth.
Observing the data taken over the course of 2020, using the top 10 most polluted cities on record throughout the state, a pattern somewhat emerges as to when the PM2.5 numbers are at their highest. In every single city, the pollution level manages to maintain a respectable reading in the months of May and October, with all cities on record coming in within the WHO's target goal of 10 μg/m³ or less. To use the city of Bethlehem as an example, its October reading was 9 μg/m³. This then rose rapidly, with a reading of 15.1 μg/m³ being taken in November, and then a further rise up to 17.8 μg/m³ in December.
This is a trend across all the cities, which saw a good reading of air quality come in over October, which then rapidly rises for the last two months of the year, making them two of the most polluted months. However, there are also other times of the year in which the PM2.5 count rose higher, albeit with less of a distinct pattern to them. The summer months also hold some sporadic rises in PM2.5, and to cite a few examples, the cities of Bethlehem, McKeesport, Bakerstown and Clairton all experienced a rapid rise in pollution from May through to July, with PM2.5 readings of 14 μg/m³, 15 μg/m³, 15.7 μg/m³ and 14 μg/m³ all being present in the month of July across all of the aforementioned cities. December was a month that was also subject to many awful readings of PM2.5, with the highest reading of pollution present throughout the state being taken in Cheswick, with a reading of 22.9 μg/m³ in December 2020.
In closing, the cleanest months of the year consistently came in during May, September and October (as well as April, with the exception of having a higher reading taken in Boiling Springs). However, the months of July, August, November and December all presented with the highest readings across the various cities. These are times in which the air would be at its most permeated with smoke, haze and other dangerous air contaminants.
As within all cities across the world, there are no groups of people that are truly immune to the damaging effects that air pollution can bring. However, there are certain groups that are even more at risk for adverse health effects to occur. These include ones such as young children and the elderly, as well as those with preexisting health conditions or compromised immune systems. Pregnant mothers are also particularly at risk as well, with cases of miscarriage, premature birth or low birth weight all being possible when excessive pollution exposure occurs.
Some of the most prominent pollutants found in the air in Pennsylvania would be ones such as nitrogen dioxide (NO2) as well as sulfur dioxide (SO2). These both find largescale release from vehicles, as well as also being found emanating from factories or anywhere that sees combustion taking place. Nitrogen dioxide finds itself one of the main offenders in its release from vehicles, and the various oxides of nitrogen (NOx) that go into forming this chemical compound can also find themselves being converted into ozone (O3) under the right conditions.
When NOx or other chemicals and gases are exposed to enough solar radiation present in the sun, large amounts of ozone, or smog as it is commonly known, can form in thick blankets, often occurring more commonly during the summer months when there is an abundance of sunlight, as well as the mass movement of vehicles across the city.
Other pollutants include ones such as black carbon and volatile organic compounds (VOC's). Black carbon is the main component of soot, and can often be found in large quantities in areas that see a high volume of traffic (along with nitrogen dioxide). Besides being visually unappealing, it is also a potent carcinogen when inhaled, and has climate changing properties due to its ability to convert solar radiation directly to heat.
Some examples of VOC's include chemicals such as toluene, xylene, methylene chloride, ethylene glycol and benzene. These are all extremely harmful to human health, and present a great danger due to their volatile nature causing them to stay in a gaseous state even during colder temperatures, hence easier to respire. These are some of the most prominent pollutants that would be found in the air throughout Pennsylvania, most concentrated within pollution hotspots and thus creating a higher risk for those who live nearby, as well as many citizens within a large radius, due to the ability of smoke and haze to get blown vast distances by the wind and affect people far away from its original source.