APES 06.01 Pollution and Smog

How is thermal inversion related to smog?

A thermal inversion is a trapped area of cool air under an area of warm air. The motion of air stops, which means the smog that is created remains in an area.

Anthropogenic air pollution

when we talk about air pollution, we are generally talking about pollution that is anthropogenic, which is to say, caused by human beings. And this sort of pollution is detrimental to the environment over the long term.

More secondary pollutant reactions

with sunlight as a catalyst, hydrocarbons and volatile organic compounds (VOCs) react with oxygen gas and nitrogen dioxide to form peroxyacyl nitrates (PANs). UV light + hydrocarbons or VOCs + O2 + NO2→PANs

Asthma

Asthma is a condition that occurs when the bronchial airways become inflamed. Asthma cannot be cured, but it can be treated and managed. As many as 255,000 people died in 2005 from asthma, with 80 percent of those deaths in low- and low-to-middle-income countries. It is the most common chronic disease in the world among children. Symptoms of asthma include shortness of breath, tightness in the chest, an audible whistling or wheezing sound when exhaling, and bouts of coughing or wheezing. Symptoms can vary in severity significantly from person to person. Asthma is caused by a number of factors including indoor and outdoor allergens. Examples of indoor allergens might include dust mites and pet dander, while outdoor allergens might including pollen molds, air pollutants, and tobacco smoke. Medications can cause asthma, as can physical exercise. There is also a correlation between urbanization and asthma—an increase in the urbanization in developing and developed countries is accompanied by an increase in the occurrence of asthma. Everyone does not get asthma. A family history of asthma, low birth weight, respiratory infections as a child, and being overweight can predispose you to asthma. Environmental triggers, such as exposure to secondhand smoke and pollutants, can also be factors in triggering asthma.

What factors cause asthma?

Asthma is caused by a number of factors including dust mites, pet dander, pollen, molds, air pollutants, and tobacco smoke.

Clean Air Act

Legislation that protects and provides ways for improving the air quality in the United States.Ozone, particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead are regulated by the Clean Air Act, which sets standards for these pollutants called the National Ambient Air Quality Standards. As a guiding framework for work in air quality, the Clean Air Act brings together federal, state, and local agencies to control levels of these pollutants from cars, factories, and other sources.

Primary pollutants reactions

Many air pollutants originate in fossil fuels, which contain large amounts of carbon. This carbon exists in fossil fuels because they contain the remains of life, and carbon is the building block of all life (on Earth). Although air pollutants can develop from evaporation, friction, and combustion, the greatest contributor to air pollutants by far is combustion. Combustion of fossil fuels creates a reaction with carbon and oxygen to produce carbon dioxide and carbon monoxide. C + O2→ CO2, 2C + O2→ 2CO, Sulfur is also a component in fossil fuels, particularly coal. During combustion, sulfur reacts with oxygen gas to produce sulfur dioxide. S + O2→ SO2, As you know, most of the air in the troposphere is composed of nitrogen (nearly 80 percent). At normal temperatures, nitrogen and oxygen don't react. However, during combustion or other high temperature processes, nitrogen reacts with oxygen to form nitrogen oxide. N2 + O2→ 2NO

Technology advances to reduce pollution

Mobile sources of pollution, such as cars and trucks, can be technologically adapted to burn fossil fuels more cleanly. A catalytic converter, which attaches to the exhaust system, produces water and carbon dioxide from carbon monoxide and hydrocarbons. Although catalytic converters on vehicles reduce air pollution from carbon monoxide and hydrocarbons, they increase carbon dioxide emissions, which contribute to global warming. This is clearly not a long-term solution. Stationary sources of pollution, such as electric power plants that use coal, have a number of options to reduce their pollutants. Bag filters can remove some of the particulate matter that is emitted from the smokestack, but not gases, such as sulfur dioxide. Special tools called cyclones also remove particulate matter, but not gases, though they use centrifugal force in a cylinder. Electrostatic precipitators also remove particulate matter, but not gases, though they pass particulate matter through an electric field, charging the particles, and then turning the field off to separate the particles. The only widespread technological solution to remove particulate matter and sulfur dioxide is the scrubber. In a scrubber, air passes through a combination of water and lime, which removes 99 percent of particulate matter and 80 to 95 percent of gases. Although this creates a toxic byproduct, it is effective at removing air pollution.

Mobile Sources

Moving sources of pollution. (cars) These, but primarily cars, account for more than half of all air pollution in the United States.

Stationary Sources

Non-moving sources of pollution. These include factories, including power plants, chemical plants, oil refineries, and commercial facilities.

Exosphere

The outermost layer of the atmosphere is the exosphere. This is the outermost layer of the atmosphere; satellites are found here.

VOCs (volatile organic compounds)

Organic compounds that can evaporate readily from solid or liquid form. They originate from industrial and commercial processes (50 percent), motor vehicles (45 percent), and consumer solvents (5 percent), including cleaning, disinfecting, and degreasing products. They contain a variety of chemicals with short- and long-term effects on human health.

Secondary Pollutants

Pollutants that begin as primary pollutants and change form in the atmosphere.

Primary Pollutants

Pollutants that come directly from the source without reacting in the atmosphere.

Second Clean Air Act

The first passage of the Clean Air Act occurred in 1963, and a significantly stronger act was passed in 1970 followed by a large revision in 1990. Since the stronger Clean Air Act passage in 1970, which set emissions standards for automobiles and new industries and set air quality standards, several positive changes have occurred: the six most common pollutants have decreased by more than 50 percent; air pollution from large industrial sources has been reduced almost 70 percent; and the ozone-depleting materials have almost ceased to be produced.

Thermosphere

The layer extending from the mesopause to the exosphere is the thermosphere. This is the layer extending from the mesopause to the exosphere; space shuttles and auroras are found here.

Mesosphere

The layer extending from the stratopause to the thermosphere is the mesosphere. This is the layer extending from the stratopause to the thermosphere; meteors are found here.

Stratosphere

The layer extending from the tropopause to the stratopause is the stratosphere. This is the layer from the tropopause to the stratopause, which protects us from radiation; jets are found in the lower portion.

Troposphere

The layer immediately above Earth's surface is the troposphere. This is the layer immediately above Earth's surface, which contains most of the mass of the atmosphere and is where we live; weather occurs here.

Thermal Inversion

Thermal Inversion: A phenomenon in which a warm air mass moves over and traps a cool air mass, disrupting normal air convection. The Great Smog in London was partially created by a thermal inversion. In the atmosphere, the air adjacent to the surface of Earth is normally warmer than air above it. In other words, the air is cooler the higher you move in the atmosphere. This phenomenon occurs because the atmosphere is heated by solar radiation, which is absorbed by Earth and, in turn, heats the air above it. Near a warm front or ocean upwelling, a warm air mass can move over a cool air mass, which produces a thermal inversion. In regions away from the ocean, the land can retain more heat than is received by radiation, particularly overnight. This also produces an inversion of temperatures. Regardless of location, when a temperature inversion is created, the convection effect ceases to function. This means the air effectively stops moving in a larger pattern, and the pollution is not dispersed. Large cities such as Los Angeles, Mexico City, and São Paulo are affected by thermal inversion, but smaller cities, such as Salt Lake City, Utah, and Oslo, Norway, are also affected.

Biogenic pollutants

Volcanoes release compounds into the atmosphere; wind storms stir up and carry particulate matter; forest fires produce tons of ash. These are introductions of pollutants, but they are natural and often biogenic, meaning they are influenced or caused by living organisms. Generally, biogenic pollutants do not cause long-term effects on the environment.

PANs

are products of a reaction between peroxyacyl radicals and nitrogen dioxide using UV light as a catalyst. PANs are respiratory and eye irritants and are considered secondary pollutants, because they are not directly created by factories, transportation, or power plants.

Secondary pollutants reactions

are the result of reactions of primary pollutants in the atmosphere. Nitric oxide reacts with oxygen to produce nitrogen dioxide, which causes the brownish haze in smog. 2NO + O2→2NO2, Nitrogen dioxide reacts with light to produce nitrogen oxide and oxygen, which, in turn, reacts with oxygen gas to form ozone. NO2 + UV light→ NO + O and then O + O2→ O3

The Great Smog

in 1952 in London killed thousands of people with deaths attributed to pneumonia, bronchitis, tuberculosis, and heart failure. In December of 1952, the weather was unusually cold and people burned coal to stay warm. The resulting smoke from coal burning stoves, particulate matter, and emissions of sulfur along with damp weather created one of three key conditions for deadly smog. The other conditions involved a fog, which had remained in the area, and high humidity, which trapped the smoke close to the ground when the air stopped moving.

Sulfurous smog

is the type of smog that exists in New York, Philadelphia, St. Louis, and London, England, and other cities that use coal for heat—these are cities that are in cold, moist climates and are generally older in terms of development. Sulfurous smog is often associated with damp weather and accompanied by a large amount of particulate matter. Cities that suffer from sulfurous pollution have been referred to as "gray-air cities." The winter air, particularly on cold days, can be particularly polluted.

Photochemical smog

is the type of smog that exists in the United States in Los Angeles, Denver, Albuquerque, and Vancouver, Canada—these are cities that are in warm, sunny climates and are generally newer in terms of development. Their photochemical pollution is created by reactions between unburned hydrocarbons and nitrogen oxides from fossil fuel-burning automobiles creating secondary pollutants including ozone, formaldehyde, and PAN. Cities that suffer from photochemical pollution have been referred to as "brown-air cities." Ozone, one of the most prevalent compounds in photochemical smog, negatively impacts the respiratory system in human beings, damages plants, and can break down rubber on cars.

Types of pollution and their types

ozone = secondary, particulate matter = both, carbon monoxide = primary, nitrogen oxides = both, sulfur dioxide = primary, lead = primary

There are two basic types of smog

photochemical and sulfurous.