Section 12 1 What Causes Air Pollution Air

Section 12 -1: What Causes Air Pollution? § Air pollution: collection of harmful substances released into the atmosphere § Some from natural sources-sand, dust storms, volcanic eruptions, forest fires § Human activity = burning fossil fuels is the major source of air pollution that continues to grow § Notice on map that areas with a lot of air pollution (red) are near large cities § Burning gasoline and pollution from power plants are 2 major sources

Primary and secondary air pollutants § Primary pollutants: put directly into the air by humans (car exhaust, VOC’s, sulfur dioxide created when electrical power is generated) § Secondary pollutants: primary pollutants react with other substances in the air (groundlevel ozone created when UV rays of the sun cause oxygen to react with automobile emissions)

§ Photochemical smog – yellow brown haze formed when sunlight reacts with oxide pollutants from cars react with air-secondary pollutant – Example: Ozone (O 3) very corrosive, nitrogen dioxide – brown gas, methane – from livestock and decaying matter § Chlorofluorocarbons (CFC’s): compounds of chlorine, fluorine, and carbon once used in refrigerators, ac’s, aerosol cans, and the production of foams

Outdoor pollutants § Particulates: tiny solids suspended in the air (Examples: ash, dust, soot, plant pollen) – Can be inhaled and become trapped in the lungs § Gases – usually oxides – compounds of oxygen and another element – Released when fossil fuels are burned

Indoor Pollutants § Indoor Pollutant effects are multiplied by poor air circulation and the long amounts of time people spend inside § Cigarette smoke § Microorganisms – bacteria and fungi from air ducts and vents § Radon – most deadly form of indoor air pollution – colorless, odorless, radioactive gas – comes from soil when radium breaks down § Asbestos – minerals that form in long thin fibers – material used in insulation that has been banned in US

How does air pollution effect an ecosystem? § Ozone and sulfur oxides – hazardous to plants, cause stems to be brittle and leaves spotted § Smog: when air pollution hangs over urban areas and reduces visibility § Temperature Inversions: occurs when the air above is warmer than the air below – usually occurs in cities because the air gets trapped – Sometimes the air near the ground is colder than the air above – Pollutants become trapped near the surface of the ground – Example: Los Angeles – cities in valleys, so smog is trapped

Section 12 -2: Air, Noise, and Light Pollution Air pollution and living things § Pollution linked to many health problems and can worsen existing medical conditions § Carbon monoxide – binds to hemoglobin in oxygen’s place and can cause death § Ozone and oxides – irritate eyes and respiratory tract-short term effect § Emphysema – disease in which tiny air sacs in the lungs break down-long term effect § Lung Cancer – 150, 000 deaths per year in US-long term

Controlling Air Pollution § Natural controls – precipitation is most effective – particles in air stick to precip and fall to the ground – many aerosols dissolve in rain – CO 2 removed biologically by plants and microorganisms, also removed by ocean waters (cooler temps hold more)

§ Human controls – – Emission control standards for automobiles § Pollution control devicecatalytic converters remove pollutants from exhaust § Use unleaded gas, cars get better gas mileage than in past (reduce lead pollution by 90%) § Will always put out some pollution when gas is burned § Electric cars, hybrid cars – Zero Emissions Vehicles – no tailpipe emissions

Human Controls, cont. – Legislation (EPA)– Clean Air Act 1970 § Requires pollution control devices in factories § Regulates vehicle emissions – Power plants – Burn fossil fuels to produce electricity § use techniques to remove pollutants from exhaust Pollution Control Devices § Scrubbers: pollution control device that moves gases through a spray of water that removes many pollutants § Electrostatic precipitator- pollution control device filtration device that removes fine particles, like dust and smoke, from a flowing gas

Noise Pollution § Noise pollution: Unwanted sound § Comes from airplanes, machinery, loud concerts, etc. § Causes annoyance, stress, hearing loss § Sound measured in decibels – 70 -80 d. B = annoyance, hearing loss – 120 – 130 d. B = physical pain and hearing damage § Noise Control Act 1972 – sets standards for maximum noise levels in workplace

Light Pollution § Does not present a direct hazard to human health § Diminishes our view of the night sky § Energy often wasted – When lights are pointed upward (billboards, buildings) – Poor quality street lights – Can be minimized by using time controls

Section 12 -3: Acid Precipitation § Discussion Prompt: How have you been affected by acid rain?

Acid Rain – Acid rain: precipitation that is more acidic than normal § Normal precip = 5. 6 p. H – Water in the atmosphere reacts with sulfur and nitrous oxide to form nitric acid and sulfuric acid § Strong and corrosive – Falls on forests and accumulates in mtn. lakes making them uninhabitable by fish § Absence of aquatic life disrupts ecosystems – Damages trees and destroys forests

International Conflict and Cooperation § Acid rain can be released in one area and fall in another – half of acid rain that falls in SE Canada results from pollution created in the NE United States § Signed the Canada-US Air Quality Agreement in 1991 to reduce emissions in both countries – See map on p. 339 – China burns large amounts of high-sulfur coal that creates acid rain that falls throughout Asia