TAILIEUCHUNG - Lecture Environmental science - Chapter 21: Air pollution
Air pollution was on an unsustainable track causing photochemical smog and acid depositions, along with health disasters and increased mortality. Indicators, such as acid and sulfate depositions, ambient levels of pollutants, and asthma hospitalizations, that show the current track are decreasing but are still at detrimental levels. Chapter 21 provides knowledge of air pollution. | Ch. 21 Air Pollution Air pollutants consist of chemicals in the atmosphere that have harmful effects on living organisms and/or inanimate objects. Why Do We Care? (humans) We inhale 20,000 liters of air each day Causes 150,000 premature deaths in the world each year (53,000 in .); aggravates other diseases . human health costs from outdoor air pollution range from $40 to $50 billion per year (CDC) Health impacts - acute – pollutants bring on life-threatening reactions w/in a period of hours or days; causes headache, nausea, irritation - Chronic – pollutants cause gradual deterioration of health over years and low exposure - Carcinogenic – pollutions that causes cancer . benzene Why Do We Care? (not human) Damage to Plants - Agriculture – crops loss ~$5 billion/year - Forests – significant damage to Jeffrey and Ponderosa Pine along Sierra Nevada; tree growth declined 75% in San Bernardino Mountains - suspected to increase plant diseases and pests Damages buildings, bridges, statues, books Aesthetics: It looks ugly. We all try to avoid living in polluted areas (admit it ) Major Outdoor Air Pollutants Primary – direct products of combustion and evaporation Secondary – when primary pollutants undergo further reactions in atmosphere Suspended particulate matter (primary) Volatile Organic Compounds (secondary) Carbon Monoxide (primary) Nitrogen Oxides (can be both) Sulfur Oxides(primary from combustion of coal) Ozone and other photochemical oxidants (secondary) Acid Deposition Acidic precipitation and dry fallout Acids and Bases pH-log of hydrogen ions in a solution. Therefore each number higher on the pH scale is 10X more basic Basic- OH- (hydroxyl ions) over 7 on the pH scale Acidic-H+ ions under 7 on the pH scale Neutral- pure water is 7 on the pH scale Normal rain is slightly acidic-pH Acid rain is defined as less than a pH of Deposition picture Sources Natural: a. Sulfur: Volcanoes, sea spray, microbial b. Nitrogen oxides: lightening, forest fires, microbial Anthropogenic (human caused) a. Sulfur oxides: coal burning plants, industry, fossil fuels. b. Nitrogen oxides: power plants, industrial fuel combustion, transportation c. Effect areas hundreds of miles from the source of emissions, generally not the whole globe d. Both sulfur oxides and nitrogen oxides are primary components of acid rain. Indoor Air Pollutants 1. Types: benzene, formaldehyde, radon, cigarette smoke 2. Sources: off gassing from furniture, rugs and building materials, dry cleaning, cleaning fluids, disinfectants, pesticides, heaters 3. Buildings with too many indoor air pollutants are called “sick buildings” because more than 20% of the people are sick due to occupying the building. Solutions: Reducing Emissions Best way = Conservation, just use less! Input Control (pollution prevention) Cleaner burning gasoline and coal with low-sulfur increased fuel efficiency and appliance efficiency alternative modes of transportation -Mass transit, Walking, Bicycling, Electric vehicles d. Switch to renewable forms of energy Reducing Emissions (input control) d. catalytic converter- complete oxidation of hydrocarbons (VOCs) and carbon monoxide to CO2 and H2O Output Pollution Control Coal washing-using large amount of H2O to leach out the sulfur Fluidized bed combustion-produces a waste ash that must be disposed of Output Control Technologies Scrubbers are “liquid filters” The exhaust from burning fossil fuels runs through a spray of H2O containing lime (CaCO3) SO2 + CaCO3 CaSO3 + O2 Required since 1977
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