Air pollution is caused by high concentrations of gases and particles emitted form combustion sources (vehicles, power plants, industries)

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1 AIR POLLUTION Clean Air Act & Criteria Pollutants Motor Vehicle Emissions: 7.8 Indoor Air and Box Models: 7.12 Air Pollution Meteorology: 7.10 Gaussian Plume Modeling:

2 Air pollution is caused by high concentrations of gases and particles emitted form combustion sources (vehicles, power plants, industries) Good old days: coal burning sulfurous smog (combination of smoke + fog) Famous smog event in London England killed thousands of people The term smog comes from the combination of fog and smoke (i.e. particles) that characterized such pollution events. After this happened Britain passed a Clean Air Act to reduce emissions to protect human health 2

3 These days most urban air pollutants are from incomplete combustion of vehicle emissions. Ideal case 100% combustion efficiency Hydrocarbon fuel + O 2 CO 2 + H 2 O Real World Hydrocarbon fuel + AIR CO 2 + H 2 O + + NO + NO 2 (called NO x from N 2 in air) + unburnt fuel + partially oxidized fuel (i.e CO, HCHO) + oxidized fuel contaminants (i.e. SO 2 ) + particles (these may contain metals) + ash (unburnable materials) These emission react in the presence of sunlight to create ozone, the major component of photochemical smog: Volatile organic compounds + NOx + sunlight O 3 + particles + host of products Primary pollutant = Secondary pollutant = 3

4 Carbon Monoxide and Ozone in Houston, Texas 210 ppbv AM rush hour wildfire EPA standard 75 ppbv Pullman 4

5 Reactions that make Ozone (p. 387) 5

6 To combat sulfurous smog and photochemical air pollution the US congress passed the Air Pollution Control Act in 1955 provided funding for research This was followed by a series of Clean Air Act Amendments The 1970 Amendments established National Ambient Air Quality Standards (NAAQS) for certain pollutants. The States were (and still are) required to submit State Implementation Plans (SIP) that detail how they would meet these standards. cities set emissions limits on NOx, VOCs, etc businesses need permits to emit these pollutants The EPA sets limits on how much of a pollutant can be in the air anywhere in the United States. This ensures that all Americans have the same basic health and environmental protections. The law allows individual states to have stronger pollution controls, but states are not allowed to have weaker pollution controls than those set for the whole country. Last CAA Amendment was in

7 1990 Clean Air Act contents Title I Air Pollution Prevention and Control The purposes of this title are - (1) to protect and enhance the quality of the Nation's air resources so as to promote the public health and welfare and the productive capacity of its population. (2).. Sets NAAQS for criteria pollutants Sets emission standards for hazardous air pollutants Title II Emission Standards for Moving Sources motor vehicles, urban buses, aircraft Title IV Acid Deposition Control regulates emission of SO 2 and NO 2 to reduce acid rain this has been very successful, acid rain is yesterdays story Title VI Stratospheric Ozone Protection regulates phase-out of CFCs and halons in adherence to the Montreal Protocol 7

8 National Ambient Air Quality Standards, 2008 Primary Standards Secondary Standards Pollutant Level Averaging Time Level Averaging Time Carbon Monoxide 9 ppm (10 mg/m 3 ) 35 ppm (40 mg/m 3 ) 8-hour (1) 1-hour (1) None Lead 1.5 µg/m 3 Quarterly Average Nitrogen Dioxide ppm (100 µg/m 3 ) Annual (Arithmetic Mean) Particulate Matter (PM 10 ) 150 µg/m 3 24-hour (2) Particulate Matter (PM 2.5 ) 15.0 µg/m 3 Annual (3) (Arithmetic Mean) 35 µg/m 3 24-hour (4) Ozone ppm (2008 std) 8-hour (5) 0.08 ppm (1997 std) 8-hour (6) 0.12 ppm 1-hour (7) (Applies only in limited areas) Sulfur Dioxide 0.03 ppm Annual (Arithmetic Mean) 0.5 ppm (1300 µg/m 3 ) 3-hour (1) 0.14 ppm 24-hour (1) 8

9 Health Effects Ozone: strong oxidant, damages lung tissue, decreases pulmonary function. Eye irratation. Carbon monoxide: binds to hemoglobin in blood asphyxiant, Decreased exercise tolerance, headaches. NO 2 : aggravation of respiratory disease (forms nitric acid in your lungs) SO 2 : shortness of breath, chest tightness, premature deaths forms sulfuric acid in your lungs). Lead: neurotoxin, impaired childhood development, impaired blood formation PM: aggravates asthma, decreased lung function, premature death in heart and lung patients, diesel PM chemical components are thought to be cancer causing. 9

10 Masters 7.4 Emissions / Air Quality Update 120 ppbv 80 ppbv 10

11 vehicles vehicles power generation Transportation is the biggest source category for CO, NOx, and VOC (mostly due to on road vehicles). These are ozone precursors. Catalytic converters & reformulated gasoline have reduced emissions vehicles industry Vehicle miles traveled have increased 155%. 11