PHOTOCHEMICAL SMOG

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PHOTOCHEMICAL SMOG

• Swagath Navin Manohar

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Contents

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

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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

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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

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1.2 Los Angeles Smog

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

http//www.physics.ohio-state.edu
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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

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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

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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

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• 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.

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• 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

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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
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• 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

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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)
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• 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

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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
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