Air pollution and other Atmospheric hazard

1. Air pollution and other Atmospheric hazard Geog301 Urban Climatology

2. What is pollution? • Atmospheric pollution: introduction of undesirable gases and particulates by humans that potentially cause harm to living organisms • We can divide pollutants into two main categories • Primary pollutants: emitted directly into the atmosphere • Secondary pollutants: result from one or more chemical transformations.

3. Los Angeles Smog and Geography • Air pollution in Los Angeles is related to • subsidence inversions • Cool ocean temperatures • Mountains that surround the city and prevent smog from dispersing inland

4. Impact of air pollutants on human is slow, insidious health insults are usually only apparent in epidemiological analysis; is vague due to its cumulative, and delayed effects on morbidity and mortality. • PSI: pollution Standards Index (below 100 is moderate or good, above 100 is unhealthy to hazards • new Air Quality Index (AQI) incorporates the new Federal ozone and PM2.5 standards. The index is designed to provide accurate, timely and easily understandable information about daily levels of air pollution (July 1999).

5. Particulates: soots, acid aerosols, EPA standard is 150 micrograms per cubic meter of air;

8. VOCs: Volatile organic compounds. It is emitted from certain solid and liquid (a wide range of carbon-based molecules). Common artificial VOCs include paint thinners, dry cleaning solvents, and some constituents of petroleum fuels (eg. gasoline and natural gas). Trees are also an important biological source of VOC; it is known that they emit large amounts of VOCs. Another significant source of VOC emission is crude oil tanking. CH4 is also a type of VOCs. SOCs: secondary organic aerosols (through oxidation of VOCs)

9. Extinction Coefficient as a PM2.5 Surrogate PM2.5 = 7.6 g/m3 PM2.5 = 21.7 g/m3 PM2.5 = 65.3 g/m3 Glacier National Park images are adapted from Malm, An Introduction to Visibility (1999) http://webcam.srs.fs.fed.us/intropdf.htm

10. Major pollution and its impact • (1) PM10 and PM2.5: particulate matters less than 10 (2.5) micro in diameter (dust-sized) linked to bronchitis, asthma, pneumonia, and pleurisy in children. • (2) Carbon monoxide: colorless, odorless, and tasteless gas, greatest emission from human activities by complete combustion of coal, fuel oil, and gasoline (automobile). Trapped in traffic, above 100ppm, headache and dizzy. • CO in tunnels, parking garages (headache), traveling in cars in slow-moving traffic are about 10 times exposed to CO values in excess of 35 mg/m3; lengthy trip in school buses, children exposed to 15-20 mg/m3, contribute to drowsiness.

11. Major air pollutants-continue • (3) sulfur compounds (residence several days; typical concentration 10-30 µg/m3) • Sulfur oxides, the second most abundant pollutant. SO2 is heavy, pungent, colorless, highly active but not cumulative gas from coal burning industries; maximum residence time is 10 days, most form sulfur acids with water vapor in atmosphere (highly corrosive). Irritate to eyes and respiratory system and is lethal at a few parts per million. • Hydrogen sulfide (H2S), forms from organic decay when there is not enough O2 present to oxidize organic material, such as swamps, rotten egg smell, darken lead in oil-based house paints, tarnishing copper and silver. • (4) Nitrogen Oxides (100-200µg/m3): yellow-brown color, a pungent sweet odor produced from combustion at high temperatures. 3 days residence time, HNO3 (end product), contribute to acid rain and surface ozone. It may cause respiratory irritation. • (5) surface ozone (50-150 µg/m3): colorless, odorless, except at very high concentrations. Major ingredient in smog. Form near ground when pollutants such as unburned petroleum hydrocarbons, nitrogen oxides from automobiles, fossil fuel power plants react in sunlight, faster in hot sunny days, begin to from around 10AM solar time. Breaks up during night. • Irritate to eyes, lung and air passages; cough, chest pain, shortness of breath.

12. Major air pollutants-continue (6) acid precipitation • The process of deposition of acid on the surface of the earth. pH value of 7 is neutral, each number is 10 times; 5 is 100 times more acid than 7.

13. Impacts of Acid Rain 1. Fresh water: fish become endangered when PH drops to about 5.5; most species stop reproducing at pH levels of between 5.3-5.6; As acidity increases, more trace metals are dissolved in the water. Aluminum, for example, collects I fish’s gills, young fish strangle in their own mucus. • Acidity also prevents fish from absorbing calcium and sodium. Lack of calcium weakens their bone structure and their skeletons become deformed and are easily damaged; lack of sodium causes convulsions, which kill the fish. • Acid shock: sudden introduction of large amounts of acid. (spring snow melt in mountain regions). The acid is deposited in the snow crystals and remains on the ground for periods of up to several months. • The sensitivity of lakes to acidification depends on their natural ability to neutralize the acidic runoff into the lake. Lake located in areas where the parent rock is igneous and metamorphic containing lots of silicates are most sensitive to acid deposition. The dissolved minerals from these rocks result in acidic runoff. • In region where parent rock is high in the mineral salts such as calcium, magnesium, and phosphorous, lakes can better tolerate the acid runoff. (neutralize the acid).

14. Continue: acid rain impacts 2. terrestrial systems • Damage forests in mid-latitudes, especially over mountains. Fog over the mountains has frequently been measured with a pH of 2.5-3.5, dieback of forest starts at summit and progressed down the mountain to lower elevations (mount Mitchell in North Carolina). 3. human health • Hospital admittances in creased as atmospheric sulfate levels rose in a region in southern Ontario (6 million) (respiratory-related problem, especially children). • Fish from acid streams and lakes have high levels of aluminum, copper, lead, mercury, and zinc. Aluminum may be linked to the onset of Alzheimer’s disease (reduce neural function). 4. structures • Limestone and marble are soluble in acid. (marble statues).

15. Continue: pollution and impacts (7) stratospheric ozone and ultraviolet radiation • Ozone concentrates on a layer at height 12-50km (7-30 mi) atmosphere. It absorb UV at range of 0.1-0.3 microns. UV breaks O2 into single O, and combined into O3, mostly over tropical, and carried into poles. • CFCs (chlorofluorocarbons), odorless, nonflammable, nontoxic, and chemically inert. Used in refrigerators starting 1930; deodorants and hair sprays; in producing plastic foams, in cleaning electronic parts. CFC-11 molecule is 40-80 years; CFC-12 lasts 80-150 years. • CFCs breaks down by UV, releases chlorine, which interacts with oxygen atoms to reduce O3 concentration,

16. Continue: pollution and impacts Ozone hole: a loss of stratospheric ozone over Antarctica, occurred in Sep, Oct since later 1970s (loss up to 60%-90%). Ice crystals of polar stratospheric clouds (formed under extreme cold conditions), act as surfaces for reaction take place. • Results of ozone reduction at global scale: Public health: UV-B, 280 to 320 nanometer range, can damage DNA (genetic code in every living cell), thus slow growth and reduce yields.

17. Animals and humans also have adapted to UV-B; Human manufacture melanin in the skin for adaptation. This is a pigment that blocks ultraviolet radiation, A summer tan results from increased production of melanin. Persons with very fair skin do not readily manufacture melanin and sunburn easily. • Exposure to UV results in aged skin, skin cancer, and a weakened immune system. • Melanoma: a form of skin cancer. It starts in or near a mole, involves the cells that give the skin its color, mixture of black or brown, sometimes with red or blue areas. These moles continue to grow and have irregular boarder. It is least common but most lethal form of skin cancer. • Highest incidence of melanoma occurs in individuals that do not tan easily (increasing 4% each year). And younger people are found to be affected. • Avoid mid-day sun.

18. Inhaling is the principal mechanism of human exposure to air pollutants (ingested, affect eyes and skin). Some provoke allergic reactions; complicated by smoking. • Under extreme stagnation conditions, with low-level inversions and calm air, pollutants accumulated to high concentrations, often with fog formation. Cases of acute respiratory disease and deaths followed.

19. Air Pollution’s Impacts on Structures • Corrosion and deterioration (billion dollars per year in some material) • Sulfur dioxide and other strong acids (eg, oxides of nitrogen) produces acid rain and certain halogen (especially chlorine) compounds are blamed for. • Iron, high-carbon steel, zinc, copper, aluminum, nickel, and chromium are among metals subject to corrosion by pollutants. • Installations such as power lines, fencing, car parts, and rails subject to gradual deterioration. • Paints, textiles, nylon, (man-made fibers), papers (books in urban library) is also affected. Animal furs and sheep’s wool are more resistant. • Building materials (limestone, marble, slate, and mortar) are deteriorated into sulfate (calcium carbonate ingredient). • Salting street to melt snow contribute (slat crystallization) to the decay of stony materials when salt solution penetrates the cracks.

20. Major air pollution episodes, mortality in London during air pollution episode of Dec 1952.

21. 1970 Clean Air Act • Set standards for four pollutants: • sulfur dioxide • carbon monoxide • nitrogen oxides • Particulates • (lead added later) NOTE: Recent Supreme Court Action May Add CO2

22. 1990 Clean Air Act Amendments • In 1990, Congress passed the Clean Air Act Amendments. • Tighter controls on air quality • Lower limits on auto emissions • Require the use of cleaner burning fuels • Limits on CFC’s and ozone depleting compounds. Recent Updates: Integrate CO2

23. The role of trees in urban environment • “lungs of the metropolis”; • Aesthetics of town; mitigate the less-desirable aspects of urban climate (reduce urban heat island); decrease noise levels; filter out certain pollutants; improve water balance and reduce runoff. • Certain types of trees are sensitive to common air pollutants (SO2; O3; fluoride; oxidant).

24. Urban noise • Noise pollution: noisy is America’s urban environment that people living in congested sections of large cities may be hearing far less than they realize; many may develop severe hearing loss. • Aircraft, railroads, motor vehicles. • Measurement in decibels (dB), a logarithmic scale of the pressure exercised by sound waves, a sound of 60 dB is considered as the beginning of intrusive noise levels it is 1 million times higher than 0dB. An ear-piercing motorcycle noise is 90 dB; take offs at nearby airports exceed this level.

25. Table 10.2 Urban noise levels (handout).

26. Shopping center has higher noise levels than woodland (20 dB higher)

27. Traffic noise decreases rapidly with elevation above ground

28. Distinct diurnal and weekly variations in noise levels; midnight to 4am weekdays have lowest noise; increase to the 9am rush-hour level and then stay fairly constant into the evening hours. • Weekends the noise levels show less diurnal variation but more noise in the early morning hours than weekdays.

29. Protection from noise: 1. A distance of at least 25 m from the center of a roadway to residence is needed for satisfactory results; 2. one or two rows of dense evergreen trees should be planted as close to the road curb as possible, then a solid barrier and then further trees or shrubbery.