PHOTOCHEMICAL SMOG

1. PHOTOCHEMICAL SMOG Swagath Navin Manohar

2. Contents • Smog • Physical Significance • Photochemical Smog • Topography & Meterology • Future Scope • 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. December 1952 Huge amounts of coal burning 4000 people died of respiratory problems Followed by additional 8000 deaths in the following months www.martinfrost.ws/htmlfiles/smog4.gif 1.1 London Smog

5. New kind of smog Primary source- Vehicle emissions First observed in Los Angeles 1.2 Los Angeles Smog http://www.physics.ohio-state.edu

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 (NOX) • 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 3.1.1 Ozone • Production at low altitudes • NOx from exhaust gases • Ozone production is dominant when NO2/NO is greater than 3 Effects of Ground Level Ozone • Damage to crops • Irritates the respiratory tract and eyes • High levels of O3 results in chest tightness, coughing and wheezing • Increased hospital admissions and premature death

9. 3.1.2 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.

10. 3.1.3 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 http://www.uwsp.edu/geo/faculty/ritter/images/atmosphere/misc/smog.jpg

12. 4.2 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 http://www.ec.gc.ca/cleanair-airpur

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