There are six criteria air pollutants identified by the EPA as the most serious pollutants: carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), and particulates or particulate matter (PM10) and Lead (Pb). Another is VOCs. Sulfur dioxide is more of a problem in the Eastern US because of the many coal burning power plants there. In Los Angeles, ozone, carbon monoxide, nitrogen oxides and particulate matter are a problem.
Carbon monoxide is produced when there is incomplete combustion of a carbon-containing material. Automobiles are guilty of this incomplete combustion. Carbon monoxide “accounts for more than 50% of air pollution by weight nationwide and worldwide” (Hill 2010). In urban areas, automobiles can emit up to 95% of CO (Hill 2010). The problem with carbon monoxide is that it binds with the hemoglobin in a person’s body, effectively replacing the oxygen that normally binds to it. This means that there is less oxygen going to the heart. This can cause “headache, dizziness, fatigue, and drowsiness. Higher doses of [carbon monoxide], such as found in enclosed spaces with improperly operating combustion appliances, may lead to coma and death. A study was done investigating whether “maternal exposures to air pollution were associated with elevated birth defect risks in a cohort of southern California infants and fetuses delivered between 1987 and 1993.
Vehicular traffic is the major source of air pollution in the metropolitan area of southern California and is responsible for producing carbon monoxide, nitrogen dioxide, fine components of PM10, and ozone” (Ritz et al. 2002). The study found that “exposure to increased levels of ambient carbon monoxide during pregnancy may contribute to the occurrence of ventricular septal defects and exposure to increased levels of ozone may elevate the risk of aortic artery and valve defects, and possibly also of pulmonary artery and valve anomalies and of conotruncal defects in the fetus” (Ritz et al. 2002). The good news is that carbon monoxide levels are decreasing. This is due to the fact that “oxygen-containing fuel additives were added to gasoline in 20 US cities to enhance its burning in the winter, a season when engines run less efficiently. In the winter of 1991 to 1992, those cities had exceeded EPA’s carbon monoxide standard on 43 days. One year later, 1992 to 1993, after introducing oxygenated fuel, they exceeded the standard on only 2 days” (Hill 2010).
Volatile organic compounds “are compounds of carbon, and compounds that readily evaporates into the air (Hill 2010). Volatile organic compounds can cause headaches, respiratory problems, dizziness, nausea and other problems. The largest source of these volatile organic compounds is motor vehicles. Automobiles produce hydrocarbons which are the most common volatile organic compound. A big problem with these volatile organic compounds is that they combine with nitrogen oxides to produce tropospheric ozone, which will be discussed later. A good thing is that volatile organic compounds emissions have dropped in the United States. In the United States, volatile organic compounds emissions have dropped from 34 million tons in 1970 to 16 million tons in 2005 (Hill 2010).
Ozone in the stratosphere protects from harmful ultraviolet rays. However, ozone in the troposphere not only plays a role in smog formation, but it also produces health effects like “irritation of eyes, nose, throat, and lungs and a decreased ability of the lungs to function optimally” (Hill 2010). Also, “chronic [ozone] exposure can permanently damage lungs” (Hill 2010). Ozone is what is known as a secondary pollutant. This means that it isn’t directly produced. Ozone is produced when VOCs and NOx react with atmospheric oxygen in the presence of sunlight and heat. Consequently, ozone levels are higher in the summer where there is more sunshine and warmer temperatures. In LA, the main culprits guilty of creating ozone are automobiles. They produce NOx and VOCs. This means that earlier in the morning, ozone levels are low and then “vehicle exhausets from morning traffic lead to increased concentrations of NOx and VOCs” and ultimately, ozone (Hill 2010). Another problem with ozone is that it is a major component of smog. Smog is a major problem in Los Angeles because as cooler wind from the ocean blows into the city, warm air from above is descending. The mountains trap the cooler air underneath the warmer air creating an inversion layer. Smog and pollution is stuck beneath this inversion layer creating a hazardous environment for Los Angeles.
A study done on long-term ozone exposure and mortality found that “for every 10-ppb increase in exposure to ozone… [there was] an increase in the risk of death from respiratory causes of about 2.9% in single-pollutant models and 4% in two-pollutant models. Although this increase may appear moderate, the risk of dying from a respiratory cause is more than three times as great in the metropolitan areas with the highest ozone concentrations as in those with the lowest ozone concentrations” (Jerrett et al. 2009).
There are many different problems that come with nitrogen oxides. The first is that “direct exposure to NOx irritates the lungs, aggravates asthma, and lowers resistance to infection” (Hill 2010). The second is that NOx can be converted into nitrate and nitric acid, which are tiny aerosol particles. These aerosol particles can inflame the lungs when inhaled. They also “are part of the haze that affects visibility; and contribute to acid deposition” which is a whole separate issue (Hill 2010). The third problem with nitrogen oxides is that when it is combined with volatile organic compounds, sunlight and warm temperatures in the atomsphere, it is converted to tropospheric ozone which was mentioned above. The major sources of nitrogen oxides is from, like carbon monoxide, automobiles. This is why nitrogen oxides are such a problem in Los Angeles as compared to other places.
Nitrogen oxides contribute to acid deposition when, in wet conditions, it is converted to nitric acids which deposit with any precipitation or fog. In dry conditions, it is “converted to tiny aerosols of nitrate salts, which slowly settle out by gravity” (Hill 2010). Acid deposition can cause damage to trees and vegetation. It does this by leeching alkaline nutrients like calcium and magnesium from the soil. Without these nutrients, the trees and vegetation are weaker and more susceptible to disease and insect attacks (Class Notes). Acid deposition can also erode metal structures and surfaces and discolor paint. Another major problem with acid deposition is that it can cause lakes to become acidic. This can lead to death of the organisms, mainly fish, in the lake.
Particulate matter are very fine solid particles that are composed of “liquid aerosol particles and solid aerosol particles (Hill 2010). The composition of particulate matter varies. It may “contain only one chemical such as sulfate, sulfuric acid, or lead oxide. Other particles may contain a number of pollutants: organic chemicals, metals, dust (with all that it can contain), tiny bits of biological matter, etc” (Hill 2010). Particulate matter can also be different sizes; it can be visible to the naked eye, or it can be submicroscopic particles. There are two categories of particulate matter: PM 10 and PM 2.5 . The first are particles with diameters of 10 um or less and the second are particles with diameters of 2.5 um or less. Inhalation of these tiny particles can cause lung disease, silicosis, asbestosis and mesothelioma. Particulate matter also contributes to smog which was mentioned earlier.
A study looking at particulate matter and possible effects published in 2002 shows that “e ach 10-µg/m 3 elevation in long-term average PM 2.5 ambient concentrations was associated with approximately a 4%, 6%, and 8% increased risk of all-cause, cardiopulmonary, and lung cancer mortality, respectively” (Pope 2002). The study looked at the levels of PM 2.5 in the areas where the participants lived and found that “risk was especially great in Los Angeles, but also in Chicago and New York City, and in rural areas with coal-burning power plants” (Hill 2010). This is because the major sources of particulate matter includes dust and dirt raised by vehicles or wind from roads and fossil-fuel combustion, especially motor vehicles (Hill 2010).
A good thing about all of these air pollutants is that they are all regulated by the Environmental Protection Agency under the Clean Air Act, which “in 1990, Congress dramatically revised and expanded the Clean Air Act, providing EPA even broader authority to implement and enforce regulations reducing air pollutant emissions” (EPA Website 2008). The Clean Air Act has significantly decreased levels of all the six criteria air pollutants.
” Air Trends.” March 10, 2010. Environmental Protection Agency. October 25, 2010, http://www.epa.gov/airtrends/index.html.
Hill, Marquita. Understanding Environmental Pollution . United Kingdom: Cambridge University Press, 2010.
Jerrett, M., R. Burnett, C. Pope, K. Ito, G. Thurston, D. Krewski, Y. Shi, E. Calle, and M. Thun. “Long-Term Ozone Exposure and Mortality. ” The New England Journal of Medicine, 360 (11), March 12, 2009, http://0-proquest.umi.com.linus.lmu.edu/pqdweb?index=13&did=1660410481&SrchMode=3&sid=1&Fmt=4&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1288054903&clientId=7693&aid=1.
Pope, Arden, Richard Burnett, Michael Thun, Eugenia Calle, Daniel Krewski, Kazuhiko Ito, George Thurston. “Lung Cancer, Cardiopulmonary Mortality, and Long-term Exposure to Fine Particulate Air Pollution.” Journal of the American medical Association, 287 (9), March 6, 2002, http://0-jama.ama-assn.org.linus.lmu.edu/cgi/content/full/287/9/1132.
Ritz, Beate, Fei Yu, Scott Fruin, Guadalupe Chapa, Gary Shaw, John Harris. “Ambient Air Pollution and Risk of Birth Defects in Southern California.” American Jjournal of Epidemiology 155 (1), March 6, 2002, http://0-aje.oxfordjournals.org.linus.lmu.edu/content/155/1/17.full.pdf.