1 PHOTOCHEMICAL SMOG Swagath Navin Manohar

2 Contents 1.Smog 2.Physical Significance 3.Photochemical Smog 4.Topography & Meterology 5.Future Scope 6.Summary

3 1. Smog Orginally phrased by Dr.Henry Antoine Des Voeux Mixture of Smoke and Fog Famous Smogs -London or The Classical Smog -Los Angeles or The Photochemical Smog

4 1.1 London Smog December 1952 Huge amounts of coal burning 4000 people died of respiratory problems Followed by additional 8000 deaths in the following months

5 1.2 Los Angeles Smog New kind of smog Primary source- Vehicle emissions First observed in Los Angeles

6 2. Physical Significance Amount of pollutants released into the atmosphere Big problem in developing countries and in many major cities Effects Plants - reducing or stopping the growth Humans - affects heart and lungs and even genetic diseases Affects materials also

7 3. Photochemical Smog Action of sunlight upon the exhaust gases to form pollutants harmful at low altitudes Mixture of air pollutants –Nitrogen oxides (NO X ) –Ozone –Volatile organic compounds (VOCs) –Peroxyacyl Nitrates (PAN ) A major concern in urban cities-capable of travelling with wind affecting huge population

8 3.1 Pollutants in Photochemical Smog Ozone Production at low altitudes NOx from exhaust gases Ozone production is dominant when NO 2 /NO is greater than 3 Effects of Ground Level Ozone Damage to crops Irritates the respiratory tract and eyes High levels of O 3 results in chest tightness, coughing and wheezing Increased hospital admissions and premature death

Volatile Organic Compounds (VOCs) Carbon based molecules (aldehydes, ketones, hydrocarbons) Short- and long-term adverse health effects Sources –Paints; wood preservatives; aerosol sprays; cleansers and disinfectants; moth repellents and air fresheners etc. Health Effects –Eye, nose, and throat irritation; headaches; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans.

PAN Important contributor to photochemical smog Secondary pollutant-formed from other pollutants by chemical reaction Contributor to production of groundlevel ozone, by transporting NOx Powerful respiratory and eye irritants and toxic Higher concentrations lead to damage of vegetation

11 4. Topography and Meterology Two factors influencing the formation of photochemical smog 4.1 Topography Very important for formation of photochemical smog Restriction of air movement, city in valley experience more smog problem, than plains es/atmosphere/misc/smog.jpg

Temperature Inversion Increase of air temperature with height for some distance above ground causing the smog trapped close to ground Consequences –Air becomes still and dust and pollutants are no longer lifted from surface Serious problem in many cities

13 5. Future Scope Variations of different pollutants over the course of a smoggy day in Southern California (From Finalyson-pitts, BJ & Pitts JN Jr. Adv. Environ. Sci. Technol. 7, 1977)

14 Being reduced in large cities Continuing to be a threat in more developing countries Enforcement of more Environmental Protection Laws Reduction of primary pollutants (NOx and VOC‘s) NOx-catalytic converters in vehicles and industries VOC-more than 700 chemicals found released by VOCs Emmision controls are being devloped for manufactuers Still.....!!!! pose a great threat – evoporation of chemicals

15 6. Summary Smog Smoke & Fog London Smog Los Angeles Smog Photochemical Smog Pollutants (NO x,O 3, VOC, PAN) Sources Effects Factors inflencing formation Topography Meterology-Temperature Inversion

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