Title: PHOTOCHEMICAL SMOG
1PHOTOCHEMICAL SMOG
2Contents
- Smog
- Physical Significance
- Photochemical Smog
- Topography Meterology
- Future Scope
- Summary
31. 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
41.1 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
51.2 Los Angeles Smog
- New kind of smog
- Primary source-
- Vehicle emissions
- First observed
- in Los Angeles
http//www.physics.ohio-state.edu
62. 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
73. 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
83.1 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
114. 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
135. 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
156. 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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