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PHOTOCHEMICAL SMOG

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Orginally phrased by Dr.Henry Antoine Des Voeux. Mixture of Smoke and Fog. Famous Smogs ... 4000 people died of respiratory problems ... – PowerPoint PPT presentation

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Title: PHOTOCHEMICAL SMOG


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
  • www.martinfrost.ws/htmlfiles/smog4.gif

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

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/atm
osphere/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 VOCs)
  • 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 (NOx ,O3, VOC, PAN) Sources Effects
Factors inflencing formation Topography Meterology-Temperature Inversion
16
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