Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Air Pollution Chapter 18

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Outline: Natural Sources Human-Caused Air Pollution  Conventional Pollutants  Unconventional Pollutants  Indoor Air Pollution Climate and Topography Effects of Air Pollution Air Pollution Control Clean Air Legislation

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. THE AIR AROUND US Approximately 14 million metric tons of air pollution are released annually into the atmosphere in the US by human activities.  Worldwide emissions total around 2 billion metric tons. Developed countries have been improving air quality, while air quality in developing world is getting worse.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. NATURAL SOURCES OF AIR POLLUTION Natural Fires - Smoke Volcanoes - Ash and Acid components Sea Spray - Sulfur Vegetation - Volatile organic compounds Bacterial Metabolism - Methane Dust  Pollen Viruses and Bacteria

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. HUMAN-CAUSED AIR POLLUTION Primary Pollutants - Released directly from the source. Secondary Pollutants - Modified to a hazardous form after entering the air and mixing with other environmental components.  Fugitive Emissions - Do not go through smokestack. - Dust from human-activities.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Pollutants US Clean Air Act designated seven major (conventional or criteria) pollutants for which maximum ambient air levels are mandated.  Sulfur Dioxide  Carbon Monoxide  Particulates  Hydrocarbons  Nitrogen Oxides  Photochemical Oxidants  Lead

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Pollutants Sulfur Compounds  Natural sources of sulfur in the atmosphere include evaporation from sea spray, volcanic fumes, and organic compounds.  Predominant form of anthropogenic sulfur is sulfur-dioxide from fossil-fuel combustion. - Annual Emissions: 114 million metric tons

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Sulfur Compounds

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Pollutants Nitrogen Compounds  Nitrogen oxides are reactive gases formed when nitrogen is heated above 650 o C in the presence of oxygen, or when nitrogen compounds are oxidized. - Annual Emissions: 230 million metric tons

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Nitrogen Compounds

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Pollutants Carbon Oxides  Predominant form of carbon in the air is carbon dioxide. - Increasing levels due to human activities. - Annual Emissions: 8-10 billion metric tons  Carbon monoxide is a colorless, odorless, toxic gas produced by incomplete fuel combustion. - Annual Emissions: 1 billion metric tons

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Pollutants Metals  Many toxic metals occur as trace elements in fuel. - Lead Emissions: 2 million metric tons.  Mercury - Bioaccumulation in aquatic ecosystems.  Nickel, beryllium, cadmiuym, arsenic… Halogens (Fluorine, Chlorine, Bromine)  CFC’s

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Pollutants Particulate Matter  Atmospheric aerosols (solid or liquid) - Respirable particles smaller than 2.5 micrometers are among most dangerous. Volatile Organic Compounds  Organic chemicals - Generally oxidized to CO and CO 2.  Of 188 air toxics listed in Clean Air Act, two-thirds are VOC’s.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Pollutants Photochemical Oxidants  Products of secondary atmospheric reactions driven by solar energy. - Ozone formed by splitting nitrogen dioxide.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Unconventional Pollutants EPA sets emissions standards for unconventional or non-criteria pollutants that are considered especially hazardous.  Asbestos, benzene, beryllium, etc. - Most have no natural source in the environment.  Aesthetic Degradation - Noise, odor, light pollution.  Reduce quality of life.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Indoor Air Pollution EPA found indoor concentrations of toxic air pollutants are often higher than outdoor.  People generally spend more time indoors.  Smoking is the most important air pollutant in the US ,000 die annually from a disease related to smoking.  Associated costs are estimated at $100 billion annually.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Indoor Air Pollution Less Developed Countries also suffer from indoor air pollution.  Organic fuels make up majority of household energy. - Often burned in smoky, poorly ventilated heating and cooking fires.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. CLIMATE AND TOPOGRAPHY Inversions  Temperature inversions occur when a stable layer of warm air overlays cooler air, reversing the normal temperature decline with increasing height, and preventing convection currents from dispersing pollutants. - Cold front slides under warm air mass. - Cool air subsides down slope.  Rapid nighttime cooling in a basin.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Inversions

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Dust Domes and Heat Islands Sparse vegetation and large amounts of concrete and glass create warm, stable air masses, heat islands, over large cities.  Concentrates pollutants in a “dust dome”. - Rural areas downwind from major industrial areas often have significantly decreased visibility and increased rainfall.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Long-Range Transport Fine aerosols can be carried great distances by the wind.  Increasingly, sensitive monitoring equipment has begun to reveal industrial contaminants in places usually considered among the cleanest in the world. - Contaminants trapped by winds at the north pole, concentrate at high latitudes and eventually fall out as snow and ice and enter the food chain.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Long-Range Transport

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Stratospheric Ozone Discovered in 1985 that stratospheric ozone levels were dropping rapidly during September and October.  Occurring since at least At ground-level, ozone is a pollutant, but in the stratosphere it screens UV radiation.  A 1% decrease in ozone results in a 2% increase in UV rays reaching the earth.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Stratospheric Ozone Circumpolar vortex isolates Antarctic air and allows stratospheric temperatures to drop and create ice crystals at high altitudes.  Absorb ozone and chlorine molecules. - When sun returns in the spring, energy liberates the chlorine allowing the depletion process to proceed rapidly.  CFC’s believed to be main culprit.  Persist for decades.  Production eliminated in 1996.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. CFC Production

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. EFFECTS OF AIR POLLUTION Human Health  EPA estimates each year 50,000 people die prematurely from illnesses related to air pollution. - Likelihood of suffering ill health is related to intensity and duration of exposure.  Inhalation is the most common route, but absorption through the skin and consumption via food can also occur.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Human Health Bronchitis  Persistent inflammation of airways in the lung that causes mucus build-up and muscle spasms constricting airways. - Can lead to emphysema - irreversible obstructive lung disease in which airways become permanently constricted and alveoli are damaged or destroyed.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Plant Pathology Chemical pollutants can directly damage plants, or can cause indirect damage by disrupting normal growth and development patterns.  Certain environmental factors have synergistic effects in which the injury caused by the combination is more than the sum of the individual exposures. - Pollutant levels too low to cause visible effects may still be damaging.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Acid Deposition pH and Atmospheric Acidity  pH scale ranges from = Neutral; 7 = Basic  Unpolluted rain generally has ph of Carbonic acid from atmospheric CO 2.  In industrialized areas, anthropogenic acids in the air often outweigh natural sources of acid.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Acid Deposition

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Acid Deposition Aquatic Effects  Thin, acidic soils and oligotrophic lakes of southern Norway and Sweden have been severely affected by acid deposition. - Generally, reproduction is the most sensitive stage in fish life cycles.  In early 1970’s, evidence began to accumulate suggesting air pollutants are acidifying many NA lakes.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Acid Deposition Forest Damage  Air pollution and depositions of atmospheric acids are believed to be important causes of forest destruction in many areas. Buildings and Monuments  Limestone and marble are destroyed by air pollution at an alarming rate.  Corroding steel in reinforced concrete weakens buildings, roads, and bridges.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. AIR POLLUTION CONTROL Particulate Removal  Remove particles physically by trapping them in a porous mesh which allows air to pass through but holds back solids.  Electrostatic Precipitators - Fly ash particles pick up electrostatic charge as they pass between large electrodes in waste stream, and accumulate on collecting plate.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Sulfur Removal Fuel Switching  Switch from soft coal with a high sulfur content to low sulfur coal.  Change to another fuel (natural gas). Limestone Injection  Can reduce sulfur emissions by 90% by mixing crushed limestone with coal before it is fed into a boiler.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Sulfur Removal Flue Gas Desulfurization  Inject crushed limestone into stack gas stream to remove sulfur after combustion. - Dry Alkali Injection Sulfur Recovery Process  Use catalytic converters to oxidize or reduce sulfur and create chemical compounds that can be collected and sold.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Air Pollution Control Nitrogen Oxide Control  Best method is to prevent creation. - Staged Burners - Selective Catalysts Hydrocarbon Control  Use closed systems to prevent escape of fugitive emissions.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. CLEAN AIR LEGISLATION Clean Air Act (1963) - First national air pollution control. Clean Air Act (1970) rewrote original Act.  Identified critical pollutants.  Established ambient air quality standards. - Primary Standards - Human health - Secondary Standards - Materials, environment, aesthetic and comfort.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Clean Air Act Revision (1990) - Included provision for:  Acid Rain  Urban Smog  Toxic Air Pollutants  Ozone Protection  Marketing Pollution Rights  Volatile Organic Compounds  Lead Revision (1997) - Stricter standards

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. CURRENT AND FUTURE CONDITIONS In the United States, air quality has improved dramatically in the last decade in terms of major large-volume pollutants.  Cities where pollution is largely from traffic still have serious air quality problems. Major metropolitan areas of many developing countries are growing at explosive rates, and environmental quality is very poor.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Summary: Natural Sources Human-Caused Air Pollution  Conventional Pollutants  Unconventional Pollutants  Indoor Air Pollution Climate and Topography Effects of Air Pollution Air Pollution Control Clean Air Legislation

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed.