Activity 3.3.1 Air Pollution Core Activity.

Air Pollution Basics

Air pollutant are emitted from both natural sources and anthropogenic emission (Freedman, 2018). These pollutants if reach a certain amount can be dangerous for human health and cause severe damage to people. The basics air pollutant are: Sulfur, Nitrogen and Hydrocarbon and Volatile Organic Compound.

Sulfur Pollutants

The main Sulfur pollutant are Sulfur Dioxide, or SO2, and Hydrogen Sulfide, or H2S. SO2 and H2S react with Oxygen once they are emitted in the atmosphere. They both become oxidized and this process create another substance called Sulfate. Sulfate, or SO4^2- has a negative charge. Since Sulfate has a negative charge, it reacts very easily with element with positive charge creating various compounds. In fact, element with opposite charge attract each other. Atmospheric sulfate occurs as tiny particles like Ammonium Sulfate (NH4)2 SO4 and Ammonium Nitrate (NH4NO3). Sulfur gasses are emitted in nature, for example by Volcanoes. However, human Sulfur pollutants emission are “3.8-times the natural release (Freedman, 2018). Fossil fuel combustion is the first anthropogenic produces of Sulfur pollutants. Also, coal and petroleum contain Sulfur so when they are burned, they released SO2 in the atmosphere. Further sources of SO2 are “manufacturing processes, the smelting of metal ores, and the burning of natural habitats during agricultural conversions” (Freedman, 2018). In contrast, the major sources of H2S are natural sources such as sediment in shallow marine and inland waters, phytoplankton and out-gassed from oceanic waters.

Nitrogen Pollutants

There are many Nitrogen gasses. Some of them are Nitric Oxide, or NO and Nitrogen Dioxide, or NO2. NO and NO2 are often considered together and referred as NOx. Natural emissions of NOx are due to bacterial denitrification. Denitrification is a process in which soil bacteria use nitrate as a form of energy and reduced it into gaseous emissions.  NOx are also emitted when lightning convert Nitrogen N and Oxygen in NOx during a process called fixation, and by oxidation of biomass during fires. Anthropogenic emission of NOx are combustion of fossil fuels. Other Nitrogen Gasses are Nitrous Oxide, or N2O, and Ammonia, or NH3. Ammonia is mainly released by decomposition of dead biomass or by anthropogenic emission such as the combustion of fossil fuels. N2O is also knowns as the “laughing gas” and it is produced by microbial denitrification in soil and water, industrial emission and fertilizers (Freedman, 2018).

Hydrocarbon and Volatile Organic Compound Pollutants

Hydrocarbons refers to Volatile Organic Compound Pollutants that contain some combination of Hydrogen, H, and Carbon, C. One example of hydrocarbons is CH4, or Methane. Methane is mainly produced by microbes, but they are also produced by deposits of fossil duels and as during and at the end of digestion in ruminant animals. Non-Methane Hydrocarbon are all the other hydrocarbon beside methane. They are naturally emitted by living vegetation and humanly produced by during fossil-fuel mining and refining, and evaporation of solvents. Other Volatile Organic Compounds contain Oxygen, Nitrogen and other light elements (Freedman, 2018).  

Comparison of Current AQI

AQI report the daily air quality and the health effect caused by breathing the polluted air in a scale from 0 to 500. To calculate how much the air is clean or polluted, EPA consider the concentration of: ground-level ozone, particle matter, carbon monoxide, sulfur dioxide and nitrogen dioxide. The value between 0 to 50 represent a good air quality. Between 51 to 100 the air is acceptable, and it is still in the national standards. Between 101 and 150 is consider unhealthy for sensitive groups, from 151 to 200 is unhealthy, 201 to 300 is very unhealthy while 301 to 500 is Hazardous and emergency condition.

	Time of Day	AQI Current	AQI Forecast	PM2.5	O3
Visalia, CA	10:00 am	538	87	95	26
San Antonio, TX	12:00 pm	47	Moderate	47	29
Los Angeles, CA	10:00 am	51	50	51	43

All Visalia, CA, San Antonio, TX, and Los Angeles, CA have different air quality. Visalia is the most polluted one and it actually have the highest AQI in the United States at the moment. Visalia air is considered a hazardous for human health. In fact, its AQI is 108% higher than the maximum level on the AQI scale. San Antonio have the better AQI between the three cities considered. San Antonio has a 91% better air quality index when compared to Visalia and its AQI placed it in good air quality. Los Angeles is instead a little bit in the middle. Its air quality is not good, but it is not hazardous either. LA AQI is moderate and it conforms to the national standards.

Visalia has 102% more PM2.5 concentration than San Antonio and 86% more PM2.5 than Los Angeles. San Antonio has the lowest concentration but the difference from San Antonio and Los Angeles in very small. LA has only 8% more PM2.5 particles than San Antonio. Also, even if Visalia has the highest concentration of PM2.5 particles compared to the other cities, it also has the lowest O3 concentration. San Antonio differ in O3 concentration from Visalia only of 11% while Los Angeles has the highest O3 concentration. LA has 65% higher concentration of lower Ozone compared to Visalia and 48% more than San Antonio.

Comparison of Current PM2.5 and O3 to EPA Standards

PM2.5 are particle smaller than 2.5 micrometers. Since these particles are very small, they travel easily into the respiratory tract and affect lungs. Exposure to PM2.5 particles might cause short-term and long-term health effects. Some short-term effect includes nose, eye or throat irritation and short breath. Exposure to PM2.5 particle also get negatively affect medical condition such asthma and heart disease.

O3 might refer to stratosphere, but also troposphere ozone. The first one is a natural layer in the stratosphere, and it is not considered a pollutant. Instead, troposphere ozone is a pollutant and it is also called ground-level ozone. Ground-level ozone is a secondary pollutant, so it is the products of other pollutant already in the atmosphere. O3 irritates and damages eyes and respiratory system. It also cause also damage the lung functions (Freeman, 2018)

National Standard	San Antonio Current measured over 1 hour	Time of Day
PM2.5 Average measured over 24 hours - 35 μg/m3	3.8 µg/m3	2:00 pm
O3 Average measured over 8 hours - 70 ppb (137 µg/m3)	47 ppb	2:00 pm

References:

Central LA CO, CA Air Quality. (n.d.). Retrieved from https://www.airnow.gov/index.cfm?action=airnow.local_city&mapcenter=0&cityid=342.

Current AQI. (n.d.). Retrieved from https://www.airnow.gov/index.cfm?action=airnow.main.

Freedman, B. (2018). Environmental science: A Canadian perspective. Halifax, Canada: Dalhousie University Libraries.

Texas Commission on Environmental Quality. (n.d.). Retrieved from https://www.tceq.texas.gov/cgi-bin/compliance/monops/select_curlev.pl.