Air Pollution Basics
1.1 Introduction
Pollutants being released into the air is a type of process that has existed since ancient times. Back then there wasn't much air pollution but it still happened, mostly in indoor spaces due to bad ventilation, but also outdoors from things like forest fires caused by lightning and even hunting groups. The effects caused by these things were small, if existent at all. Air pollutants come from many places, and in ancient times only came from natural sources like volcanoes and swamps where dead organic material is decomposing. As society advanced so did its needs and people eventually started using fossil fuels, which cause major air pollution, to help them be more productive or comfortable with things like indoor heating. The amount of pollutants in the air has been increasing dramatically since the start of the industrial revolution (about 1750) when coal became a major fuel source used for powering and heating machinery. The EPA, or environmental protection agency, did not exist until December of 1970, so for a little over 200 years the factories and plants used for industrialization did not have to abide by any laws regarding the pollutions that their plant puts out, meaning they were just carelessly and freely dumping their pollutants into the environment with no thoughts on consequences in the future (n.d.4). The continuous development of industrialization techniques and use of fossil fuels to power machines has further driven the increase of pollutant emissions(Freedman, Bill pg. 366). In both situations, whether pre-industrial or post-industrial, the serious effects of air pollutants could be amplified to a lethal level with the right conditions where the atmosphere is stable and calm. Those right conditions refer to a natural phenomenon called "atmospheric inversion" which is when a pocket of warm air moves into a region and stays higher in the atmosphere instead of sinking down. This warm pocket of air remaining high means it could potentially and eventually be positioned to where it is sitting on top of a cold air pocket. When this warm air sits on top of that cold air it stabilizes weather conditions, and doesn't allow the pollutants at the lower level to receive any air current which helps them to be able to disperse in the upper atmosphere and be less concentrated. If an inversion is accompanied by fog, then it is known as "smog", a mix of fog and smoke (Freedman, Bill pg. 366). Smog has been known to have deadly affects on entire regions, not just individuals, where it essentially suffocates all life trapped in it. All of these pollutants in the air, including smog, contribute to the air's overall quality and can also form the perfect conditions for acid rain to occur. Acid rain is another detrimental effect caused by air pollution, and it speeds up the process of breaking things down like cars, buildings, statues, and depletes the environment of nutrients vital for survival(Why is Acid Rain Harmful?).
Since the discovery of the devastating and uncomfortable effects caused by air pollution many nations have made steps in trying to reduce their overall emissions outputs, but it is almost impossible to do in countries like China and India who's work dynamics in industrialization require the constant use of fossil fuels for production (Freedman, Bill pg. 366). This is realistically very horrible, because these places especially experience extremely high levels of air pollution, which has been proven time and time again to have nasty affects on human and environmental health (Freedman, Bill pg. 366). So the citizens of these countries have to either choose between maintaining their health by leaving the country, or dealing with the effects of the pollution because of lack of opportunities for betterment in life. For this reason, on top of many others, I firmly believe that not only do we as a race of humans need to find ways to reduce our pollutant emission levels globally, but we ultimately need to be investing more heavily into creating infrastructure designs that allow for the public and private use of renewable resources in order to power machines, homes, cars, and other technological developments that emit pollutants.
The EPA categorizes these pollutants as sulfur-based pollutants, nitrogen- containing pollutants, hydrocarbons, volatile organic compounds (VOC), and ozone (O3). A majority of these are primary pollutants which are pollutants that are emitted directly from a source. Some of them, such as certain VOCs and ozone, are secondary pollutants which are not emitted from a source, but are instead created by primary pollutants chemically reacting to the compounds and sunlight in an environment(Glossary: Primary and Secondary Pollutant). So more pollutants are in the air than many realize because of the creation of those secondary pollutants, which is just a further argument for why phasing out fossil fuels as our main energy source is so important. The maintaining of healthy air means less health problems and death will occur globally as a result of something that ultimately might have been able to be avoided.
1.2 Sulfur pollutants
Sulfur Dioxide (SO2) and Hydrogen sulphide (H2S) are the two major compounds that are focused on when analyzing sulfur air pollutants. Sulfur based pollutants are one of the most important gaseous air pollutants to focus on because of how they chemically react with other air pollutants (Freedman, Bill pg. 368-373). S02 and H2S chemically combine through a process called oxidation once they are released into the air. Oxidation is when a chemical or chemical compound chemically combines with oxygen to create a new compound(Oxidation). So our compound H2S chemically combines with the oxygen molecule in the S02, which creates the compound Sulphate (SO4-) (Freedman, Bill pg. 368). H2S oxidizes out of the air quickly, meaning it is in the air for less than one day. SO2 on the other hand oxidizes a lot slower, meaning it is in the air for a lot longer, typically four days. Due to a longer existence time in the atmosphere this specific pollutant is more likely to get spread further until it is oxidized and is no longer in the air (Freedman, Bill pg. 368).
The sulphate (SO4-) compound created through combining SO2 and H2S is a negative compound. Because it is negative the sulphate seeks to combine with positively charged chemical compounds, known as ions or cations, to form many different and new compounds like ammonium nitrate (NH4NO3) and ammonium sulphate ((NH4)2 SO4) which are secondary pollutants (Freedman, pg. 368). Secondary pollutants are pollutants created through the combination of primary pollutants and are not directly emitted from a source(Secondary Pollutant). These two secondary pollutants also make up a large part of the haze observed in cities that make seeing difficult. This sight-blocking pollution will only continue to grow worse as the populations of the world increase. More people equals more pollution (Freedman, Bill pg. 370). Typically there aren't enough cations in the air to balance all the negativity. In this case the negative compounds are balanced by combining with hydrogen ions (H+). This chemical combination creates a gas that contains sulfuric acid, which is the main component of acid rain(Freedman, Bill pg. 368). Acid rain is an undesirable predicament because it can harm forests and agricultural fields by stripping the environment of nutrients, damage fresh water sources by changing the pH or acidity levels, breakdown objects like buildings and cars, can be lethal to aquatic animals due to poisoning their homes, and cause major health problems in humans as well as make existing health problems worse (Why is Acid Rain Harmful?).
As mentioned before the Environmental Protection Agency (EPA) regulates air quality in the U.S. in order to maintain a healthy air quality. Air quality is important because keeping it in a certain range ensures the health of human, animal, and plant life (n.d.1). Humans and animals are generally a lot less sensitive to SO2, so the EPA structured its "acceptable" guideline levels for this pollutant around how plant species will react to it. Some are so sensitive they can suffer acute injuries in environments with even super low levels of SO2 that don't cause harm in general plants. Sometimes plants can still suffer damaging affects from lower levels of SO2 exposure that don't cause acute injury symptoms. These affects are known as hidden injuries, and can greatly reduce the amount of productivity and yield a plant gives (Freedman, Bill pg.370-371). This means the areas of the world being exposed to "acceptable" levels of sulfur dioxide according to the EPAs standards, especially agricultural areas, will receive less food from the plants in their environment. This can become an issue for human resource levels, as well as for wild animal food sources, and if the wild animals can't eat and die off, then that further worsens the food scarcity issues for humans.
1.3 Nitrogen Pollutants
Gases that contain nitrogen are also very important to focus on when analyzing air pollution because of the ways that they react to other chemicals in the atmosphere. The damage caused by nitrogen-containing gases focuses mostly on the way that these chemical compounds react to sunlight and UV rays through photodecomposition, because these interactions create ozone (O3), "which is a much more toxic gas" (Freedman, Bill pg. 374). Photodecomposition is when chemical compounds are broken down via light energy (Photodecomposition). Exposure to certain nitrogen-based compounds can result in impaired pulmonary (lung) functions (Pulmonary Function Tests). The EPA has set standards for the levels of nitrogen-based pollutants that can exist in one atmospheric space in order to try to maintain healthy air quality. Concentrations of these key compounds are not typically found to be high enough in the atmosphere that they affect human or plant health. The creation of toxic ground-level ozone gases are what is most concerning when it comes to considering nitrogen containing compounds in air quality control. Another worrying aspect is the acidification of rain, soil, and water systems(Freedman, Bill pg. 373-374). As mentioned above, acid rain is highly damaging and extremely toxic to human, animal and plant life.
1.4 Hydrocarbons and VOC pollutants
The last area of interest as far as air pollution basics go involves hydrocarbons and volatile organic compounds (VOCs). Hydrocarbons are a unique and diverse group of chemical compounds that have different variations in in the combinations of hydrogen and carbon. The simplest one is methane (CH4), which is a gas. Bigger, more-dense hydrocarbons can form as vapors, liquids and solids. Carbon is one of the largest contributing factors in global climate change, so reducing the output of compounds containing carbon should ultimately be a goal for every country in order to combat this environmental problem. These compounds are also important to consider when analyzing air quality because just like the nitrogen-based pollutants, organic gases, like hydrocarbons, have a chemical reaction with the sun and UV rays, which ultimately create toxic ozone gas (Freedman, Bill pg. 375).
According to the EPA, VOCs, or volatile organic compounds, are emitted as gases from thousands of different products, mostly household products like paints, windex, and pinesol, but also other products like gasoline and diesel (n.d.5) These organic gases and vapors are toxic to human health, and also react with sunlight/ UV rays in order to create ozone through photodecomposition (Freedman, Bill pg. 375).
Comparison of current AQI
2.1 What is the Air Quality Index (AQI?)
According to the EPA, the air quality index (AQI) is a guide where you can find daily reports on the quality of the air in your area as well as others. It tells you how clean, or unclean, the air is and what kind of health affects could be caused as a result of the potentially dirty air. The index itself operates on a scale of 0- 500, with 500 being extremely bad air quality. This scale, which is provided below, is broken down into 6 sections with their own numeric scale to indicate the air quality level with conditions ranging from good to hazardous. Air quality levels are calculated using the data collected on the four main pollutants outlined in the Clean Air Act (n.d.1).
(n.d.1)
2.2 Data table
| Time of day | Current AQI | AQI forecast | PM2.5 | O3 |
Mammoth Lakes, CA (highest) | 3 pm | 354 | Moderate-Good | 354 | Unhealthy for sensitive groups |
San Antonio, TX (where I live) | 3 pm | 37 | Good | 34 | 37 |
Los Angeles, CA | 4 pm | 122 | 70 | 122 | 105
|
2.3 description of data in table
The data in the table was collected to analyze different air quality levels in different areas of the U.S. The first column is analyzing Mammoth Lakes, CA whom had the highest AQI level at the time of my searching, which was around 3 PM. Their over-all AQI level was sitting at 354, meaning conditions were extremely hazardous to all life (Air Now Interactive Air Quality Map). Though their O3 levels weren't insanely high, the PM2.5 levels were which was a little odd to me considering the differences in PM2.5 levels and 03 levels compared to my other areas of interest. Some further research concluded that this is likely so high right now due to a wild fire that is currently going on in the area, which releases a lot of particulate matter into the air (Visit Mammoth). Though ozone levels were ok for everyone except sensitive groups, the total quality of the air was dangerous to all health degrees which is a perfect example of why multiple pollutants are used to calculate the air's quality. The air quality is predicted to be in the moderate/good range tomorrow which to me is an indication that the wild fire is dying down or ending.
The second column analyzes my hometown of San Antonio and its air quality around 3 PM. The AQI level was 37, which is drastically lower than in Mammoth Lakes, CA. Another huge difference in these two areas is that there is a large difference between the number for PM2.5 and O3 in Mammoth Lakes, but San Antonio's were almost the same (n.d.3). In comparison with LA, San Antonio seems to have a very good air quality, although LA is nowhere near as bad as Mammoth Lakes right now. According to some research, San Antonio's rush hour begins around 4:30 PM and ends at roughly 6 PM (Getting Around San Antonio), meaning at the time of my searching, San Antonio's AQI levels were not at their highest for the day because 1) it wasn't rush hour ,and 2) a small storm I witnessed early in the day could have aided in pushing out some of the existing pollutants to other areas. The air quality is predicted to be in the good range tomorrow which is an indication to me that conditions similar to today should be expected.
The third column is looking at the AQI for Los Angeles, CA. I believe this location was an area of interest for this particular section of the assignment because Los Angeles is know to have one of the lowest air qualities in the U.S. due to mass air pollution known as smog(Air Quality in Los Angeles). Though their air quality it is not as bad as Mammoth Lakes currently, it's still not as great as San Antonio's. A tourist website based in California states that LA's rush hour starts at 4 PM and ends around 7 PM(The Guide To Driving in Los Angeles). I gathered my information on Los Angeles around 4 PM (n.d.2), meaning that their air quality index level of 122 was not the highest it would be for the day because rush hour hadn't even gone into full swing yet. Though the PM2.5 and O3 levels for Los Angeles weren't as close together as San Antonio's, they are still more similar than the PM2.5 and O3 levels in Mammoth Lakes. Their air quality for tomorrow is projected to be at 70, which is almost half of the current level (The Guide To Driving in Los Angeles). This makes me wonder if this prediction being made is a general one, or if the prediction is made in relation to a specific time of day like in the morning or at night when their is little to no anthropogenic activity.
Comparison of the current PM2.5 and O3 to EPA standards
3.1 What is PM2.5?
PM stands for particulate matter, which comes in different types and sizes, and which is also an air pollutant that affects human health. PM2.5 refers to particulate matter that is 2.5 microns across (Freedman, Bill pg. 372). A micron is a unit of measurement involving length which is equal to one millionth of a meter (Micron), so its super small. PM is the pollution you can see in the air, and and are made of particles instead of dangerous gases like other air pollutants. Particulate matter is harmful to human health, and PM2.5 is especially dangerous to health because it is small enough to be able to enter the nose and throat where it will make its way to your lungs (Walker, Scott).
3.2 What is O3?
O3 stands for Ozone, and can be categorized into two categories: ozone in the stratosphere, and ozone in the troposphere. The stratosphere is the second layer of our earth's atmosphere, and here is where ozone typically builds up in a safe way. This layer of ozone does little to affect human health, and offers protection from the sun's harmful rays. The troposphere is the lowest atmospheric level or layer on planet earth(n.d.1). This is where all life, especially human, thrive due to proper living conditions. Ground layer ozone, a secondary pollutant, is the smog we see build up in cities. Ground layer ozone is synthesized through primary pollutants having a photochemical reaction with the atmosphere around it, meaning the pollutants chemically synthesize into new compounds due to the presence of light (Freedman. Bill pg. 375).
3.3 Health hazards
One of the particular reasons that so much attention is payed to PM2.5 and O3 specifically when handling air pollution is because of the drastic health affects these aspects can cause. Death is almost always a drastic side affect that can be caused by the ingestion of a substance at too high of a concentration, even water. With air pollution, the cause for death can range from quick and sudden suffocation, to long drawn-out suffering via health problems that were created from ingesting too much air pollution. Exposure to these pollutants can cause, as well as worsen, problems with health including chronic respiratory or heart diseases, lung diseases, asthma, and eye irritation/blindness in severe cases(Freedman, Bill pg. 379-381).
3.4 Data table
National Standard | San Antonio Current Ozone measured over 1 hour | Time of Day |
PM2.5 Average measured over 24 hours- 35 μg/m3 | 6.2 μg/m3 | 7 pm |
O3 Average measured over 8 hours- 70 ppb (137 μg/m3) | 42 ppb | 7 pm |
3.5 Description of data in table
The table above depicts data about San Antonio's air quality factors. In the second column down data shows that the national standard for PM2.5 is measured over the course of 24 hours, and is deemed safe all the way up to 35 μg/m3. San Antonio's current PM2.5 was measured at 6.2 μg/m3 and when multiplied by 24 hours to make the ratios proportionate, I found that the average PM2.5 levels in San Antonio were more than 4 times bigger than the national average, coming out to a total of 148.2 μg/m3(Latest Hourly PM-2.5 Levels). The third column down shows data on the national standard for 03 levels is measured over the course of 8 hours, and is deemed safe all the way up to 70 ppb, or 137 μg/m3 . San Antonio's O3 levels were sitting at 42 ppb per hour, and when multiplied by eight hours to make the ratio equivalent to that of the national average, I discovered that in that eight hour time period San Antonio's 03 levels exceeded that of the national average, coming out to equal a total of 336 ppm(Current Ozone 1-Hour Levels).
Works cited
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“Latest Hourly PM-2.5 Levels.” Go to TCEQ Web Page, Texas Commission on Environmental Quality, 21 Oct. 2020, www.tceq.texas.gov/cgi-bin/compliance/monops/select_curlev.pl?user_param=88502.
“Micron.” Dictionary.com, Dictionary.com, www.dictionary.com/browse/micron.
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