10/16/20091C118: Oct. 19, 2009Ch 1. The Air We BreatheOverview of Unit 1Atmospheric Chemistry‐Pollution: Smog (Ch. 1)and Acid Rain (Ch. 6)‐ Stratospheric Ozone (Ch. 2)‐ Global Warming (Ch. 3)Ch 1 OverviewSections to Read: 1.1‐1.5, 1.10‐1.14 I. Basic components of an unpolluted atmosphereII. AtmosphereRegionsRegionsTemperatu re and Pressure ProfilesIII. PollutantsWhat are important pollutants?What are the units for pollutants and how to work with them?Why is the molecule a “pollutant”? Health or environmental eff ectsWhat are the sources of pollutants?How have concentrations of pollutants been changing over time and why?What is the current status of pollution in U.S. and worldwide?10/16/20092Who’s smarter than a 5thGrader Question?What is the primary component ofWhat is the primary component of the atmosphere?I. Components of an Unpolluted AtmosphereComposition of Dry Air:Nitrogen 78%Oxygen 21%Argon 0.9%99.9%Other gases < 0.1%Carbondioxide~0 04%Carbon dioxide 0.04%Pollutants Water vapor: close to zero in desert up to 5% in rain forest10/16/20093II. The AtmosphereThe main regions of the atmosphere are:Region containing pollution isRegion containing ozone layer isRegion containing ozone layer isAirplanes fly ____ km above the earth’s surface,in which region of the atmosphere?PressurePressure = force/areaWhat generates this force?What are some common units for pressure?10/16/20094Is atmospheric pressure enough to crush a soda can?A. YesB. NoC. Not sureAll answers will earn clicker points!All answers will earn clicker points!Pressure ProfileWhat type of a functiondescribes the change inpressure with altitude?Use the equation to calculatepressure (atm) at 5 and 10 km.10/16/20095Why must planes be pressurized?A. The % composition of oxygen decreases as ltit d ialtitude increases.B. The % composition of oxygen remains the same, but the overall pressure decreases. Therefore the total amount of oxygen decreases.C. Both A and BD. Not sureAirplanes fly at an altitude of 13 km. How does the amount of oxygen at thisaltitude compare to the amount of oxygen at ssealevel?• Oxygen has a composition of 21% by volume throughout atmosphere.Guiding Questions:sea level?• What is the pressure at 13 km?• What is the pressure of oxygen at ground level?• What is the pressure of oxygen at 13 km?10/16/20096Temperature Profile of the AtmosphereWhy is there an increase in temperaturein the stratosphere ?Troposphere: 0‐17 kmStrong vertical mixing, individual moleculescan tranverse depth in a few days.Why?Stratosphere: 17‐50 kmVery small vertical mixing, years to transverse Why?III. Air PollutionNotable Air Pollution Events:In October 1948, a thick cloud of air pollution formed above the industrial town of Donora, Pennsylvania. The cloud which lingered for five days, killed 20 people and caused sickness in 6 000 of the town's 14 000 peoplekilled 20 people and caused sickness in 6,000 of the town s 14,000 people. In 1952, over 3,000 people died ov er a period of 4 days in what became known as London's "Killer Fog." The smog was so thick that buses could not run without guides walking ahead of them carrying lanterns. (Smog = Soot from coal + fog)What are important modern air pollutants?10/16/20097History of Air Clean Up• 1970 Congress Passes Clean Air Act•1970EPA is established to enforce Clean Air Act1970EPA is established to enforce Clean Air Act • 1990 Ammendments to Clean Air ActRevision and ExpansionEPA increases authorityClean Air Act sets limits on criteria polluta ntsanywhere in the USanywhere in the US.EPA can set emission limits on utilities, steel mills, chemical plants, etc.Criteria Air Pollutants and National Ambient Air Quality Standards (NAAQS)Pollutant Primary Std. Averaging TimesCO 9 ppm 8‐hour35 ppm 1‐hourLead 1.5μg/m3Quarterly averageParticulates(PM10) 150 ug/m324 hour(PM2.5) 15.0 ug/m3Annual35 ug/m324‐hourOzone 0.08 ppm 8‐hour0.12 ppm 1‐hourSulfur Oxides 0.03 ppm Annual0.14 ppm 24‐hourhttp://www .epa.gov/air/criteria.html10/16/20098Units for Criteria Pollutants• % or (pph)• ppm• ppb• μg/m3Clicker Question• The concentration of carbon dioxide in the thi 375 Wh t i thatmosphere is 375 ppm. What is the concentration expressed as a %?• A. 3.75%•B 0 375%•B. 0.375%• C. 0.0375%• D. 0.00375%10/16/20099Clicker QuestionThe NAAQS standard for sulfur dioxide tti i 0 030 E thiconcentration is 0.030 ppm. Express this concentration in ppb.A. 3 ppbB. 30 ppbC300 ppbC.300 ppbD. 3000 ppbHow small is the unit of ppm and ppb?A ppm of seconds would be the first second in 1 million seconds.dayshrdayhrssx 5.11241min60160min11016=⎟⎠⎞⎜⎝⎛⎟⎠⎞⎜⎝⎛⎟⎠⎞⎜⎝⎛A ppb of seconds would be the first second in 1 billion seconds.yearsdaysyrhrdayhrssx 7.313651241min60160min11019=⎟⎟⎠⎞⎜⎜⎝⎛⎟⎠⎞⎜⎝⎛⎟⎠⎞⎜⎝⎛⎟⎠⎞⎜⎝⎛10/16/200910Clicker Question• The local news reports that ozone levels are right at the acceptable level 012ppm Howright at the acceptable level, 0.12 ppm. How many ozone molecule do you inhale in each breath? Assume one breath contains 2 x 1022molecules.• A. 1.7 x 1013B 17 1017•B. 1.7 x 1017• C. 2.4 x 1019• D. 2.4 x