By: Tamar, Diran, Arno, Anise Air Pollution By: Tamar, Diran, Arno, Anise

Introduction The atmosphere is a gaseous envelope surrounding Earth. Atmosphere performs additional ecosystem services, such as blocking Earth’s surface from much of the UV radiation coming from the sun, moderating the climate, and redistributing water in the hydrologic cycle. Air pollution consists of gases, liquids, or solids present in the atmosphere in high enough levels to harm humans, other organisms, or materials They are various chemicals added to the atmosphere by natural events or human activities. Air pollutants are often divided into 2 categories, primary and secondary. Primary air pollutants are harmful chemicals that enter directly into the atmosphere. Example: CO2, nitrogen oxides Secondary air pollutants are harmful chemicals that form from other substances released into the atmosphere. Example: Ozone and sulfur

Air Pollution in California

Major Classes of Air Pollutants Particulate matter: consists of thousands of different solid and liquid particles suspended in the atmosphere. Particulate matter can be dangerous. It may contain materials like heavy metals or organic chemicals. They have extremely small particles, even if not toxic; can get lodged deep in the lungs. Example: soil particles soot, lead, sea salt Lead: a soft metal that is used in industrial and chemical processes has variety of health impacts. Nitrogen Oxides: Gases produced by the chemical interactions between atmospheric nitrogen and oxygen when a source of energy, such as combustion of fuels, produces high temperatures.  Consist of Nitric Oxide, Nitrogen dioxide, and nitrous oxide. Sulfur Oxide: Gases produced by chemical interactions between sulfur and oxygen. Two major sulfur oxides are sulfur dioxide and sulfur trioxide

Major Classes of Air Pollution Carbon Oxides: Gases carbon monoxide and carbon dioxide. Hydrocarbons: Diverse group of organic compounds that contain only hydrogen and carbon. Simplest one being methane. Ozone: a form of oxygen considered a pollutant In one part of the atmosphere but an essential component in another. It is a blue gas that is both a pollutant in the lower atmosphere (troposphere) and an essential component that screens out UV radiation in the stratosphere.

Air Pollution 2 main sources of air pollution are transportation and industries Urban Air Pollution Air pollution localized in urban areas, where it reduces visibility, is often called smog. Worst industrial smog is during winter Photochemical smog is another important type of smog Sunlight irritates several chemical reactions that collectively form its ingredients.

Human Health Exposure to even low levels of pollutants such as ozone, sulfur oxides, nitrogen oxides, and particulate matter can irritate eyes and inflame the respiratory tract. Evidence continues to accumulate that exposure to air pollution during respiratory illness may result in the development later in life of emphysema and chronic bronchitis. People suffering from emphysema and asthma are sensitive to sulfur dioxide and particulate matter. People at greatest risk from carbon monoxide include pregnant women, infants, and those with heart or respiratory diseases. The health effects of about 150 hazardous air pollutants produced by motor vehicles, business, and industries have not been widely studied, although long term exposure to certain air toxics have been linked to cancer.

Controlling Air pollutants Hybrid cars and natural gas- powered buses “Command and Control” technologies have been used to reduce emissions Vapor Recovery: To reduce emissions, gasoline sellers in most urban parts of the world Lower Combustion temperature in car engines reduces the formation of nitrogen oxides. Reducing the sulfur content in gas from its current average of 330 parts per million to 30 ppm or lower would significantly reduce air pollution

Clean Air Act The Clean Air Act of 1970 set the standard for modern air quality regulation. This law authorized the EPA to set limits on the amount of specific air pollutants permitted everywhere in the US. The EPA has focused on 6 air pollutants (lead, particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides, and ozone) Clean Air Act required stricter controls of motor vehicles. The Clean Air Act amendments of 1990 focus on industrial airborne toxic chemicals in addition to motor vehicle emissions.

Ozone Ozone is a form of oxygen that is human made pollutant in the troposphere but a naturally produced, essential component in the stratosphere. UV radiation is that part of the electromagnetic spectrum with wave-lengths just shorter than visible light. Stratospheric Ozone thinning: the accelerated destruction of ozone in the stratosphere by human- produced chlorine and bromine containing chemicals. Causes of Ozone Depletion Chlorofluorocarbons: Human made organic compounds of carbon, chlorine, and fluorine that had many industrial and commercial applications but were banned because they attack the stratospheric ozone layer. Effects of Ozone Depletion Higher levels of UV radiation reaches Earth’s surface. Excessive exposure is linked to cataracts, skin cancer, and weakened immunity. Scientists are concerned that increased levels of UV may disrupt ecosystems. Example: Antarctic phytoplankton have been declining . High level of UV radiation may also damage crops and forests

Ozone Depletion

Acid Deposition Acid Deposition: sulfur dioxide and nitrogen dioxide emissions react with water vapor in the atmosphere to form acids that return to the surface as either dry or wet deposition. Industrialized countries in the Northern Hemisphere had been hurt the most. Measuring the Acidity: pH scale, Runs from 1-14, pH of 7 is neither acidic nor basic whereas PH of 7 or less indicates an acidic solution. Distilled Water has a pH of 7 while tomato juice has 4. Acid Deposition occurs when sulfur dioxide oxides are released into the atmosphere, they combine with moisture to form acids and then are deposited in land through rain or snow. Coal burning power plants, large smellers, and industrial bailers are the main source of sulfur dioxide emissions and produce substantial amount of nitrogen oxides. Sulfur dioxide and nitrogen oxide emissions react with water vapor in the atmosphere to form acids that return to the surface as either dry or wet deposition.

Acid Deposition Effects: The link between acid deposition and declining aquatic animal populations is well established. Acid deposition is one of several stressors that interact, contributing to the decline and death of trees. Acid deposition increases soil acidity, causing certain essential mineral ions, such as calcium, to leach out of the soil. Acid deposition does not recognize borders between states or countries, it is entirely possible for sulfur and nitrogen oxides released in one spot to return to the ground hundreds of km from the source.

Forest Decline

Forest Decline It is a gradual deterioration and often death of many trees in many forests. Air pollution and Acid rain contribute to forest decline in many areas. No single factor accounts for forest decline which appears to result from the combination of multiple stressors – acid deposition, troposphere ozone, UV radiation, insect attack, drought, climate change, etc. Air quality is deteriorating in developing countries. Rapid industrialization, a growing number of cars in developing countries, and lack of emissions standards are contributing to air pollution, particularly in urban areas.

Global Distillation The global distillation effect is the process in which volatile chemicals evaporate from land as far away as the tropics and are transported by winds to higher latitudes, where they condense and fall to the ground Volatile chemicals contaminate some remote polar regions as a result of the global distillation effect. Tobacco smoke contains many hazardous chemicals and causes many diseases in smokers and passive smokers. Indoor tobaccos can be a significant workplace hazard to nonsmokers who spend large amounts of time in smoky areas.