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PHOTOCHEMICAL SMOG
By AKASH BISWAL
3rd Semester ,MSc ENVIRONMENTAL
SCIENCE DEPT-BOTANY
WE KNEW THAT :
A smog is a mixture of Smoke + fog
Name Industrial Smog
Photochemical Smog
Weather Cool,Damp SunnyContent Particulate,S
O2
Nox,O3,Hydrocarbon
Chief Sourse Coal Combustion
Gasoline Combustion
Smog
Industrial SmogOr
London Smog
Photochemical SmogOr
Los Angels Smog
If so,then what is a photochemical smog
Photochemical Smog is an air pollution ,formed when photons of sunlight hit molecules of different kinds of pollutants in the atmosphere
AIR POLLUTANT
Primary Air PollutantNOx , VOCs
Secondary Air Pollutant
Ozone(O3) , PAN
Process Involving Formation Of Photochemical Smog
Formation of Oxides of Nitrogen
N2+O2→2NO2NO+O2→NO2
NO2+hν→NO+O
Photolysis
Formation of Tropospheric Ozone
Nitrogen Oxide
O∙+O2→O3NO+O3→NO2+O2
O3+RH→RCO2∙+RCHO+R2CO
HydrocarbonO+RH→R∙ + RCO∙ (acyl
radical)RCO∙ +O2 →RCO3
∙ (peroxyacyl radical)RCO3
∙+ NO2 → RCO3NO2R=CH3,CH3 + NO2→ CH3CO3NO2
Effect on Human Health
&Plants
Smog can irritate and inflame pulmonary membranes, causing chest pains, coughing, and throat irritation. Other illnesses such as colds and pneumonia can also be brought on by exposure to smog.
People with asthma problems are under an even greater threat. Even minor exposure to smog may cause these people to get asthma attacks.
Smog slowly ruins people's lungs to an extent as great as that of cigarettes.
SOURCES AND EFFECT OF PHOTOCHEMICAL
SMOG
CHEMICAL SPECIES
ANTHROPOGENIC
SOURCES
ENVIRONMENTAL HEALTH & EFFECTS
COMMENTS
Nitrogen Oxides(NO2,NO,)
• Combustion of gasoline in Automobiles
• Gasoline , Coal, Gas Industry
• Decrease visibility due to yellowish nature of NO2
• Eye irritation • NO2 responsible
for suppressing growth of plants
• Prolong exposure to Nitrogen Dioxide increases respiratory infection
• May increase the cases of cancer
• Only 5% of the total concentration of NO2 results From combustion and most is formed from reaction involving NO from lightening, Bacterial action in soil.
Volatile Organic compound(VOCs)
Evaporation of solvents
Incomplete combustion of fossil fuel
Evaporation of fuels
Eye irritation
Respiratory irritation
Decreased visibility due to Blue-brown haze
VOCs in the atmosphere includes naturally occurring compounds such as Terpenes from vegetation
Ozone(O3)
• Formed From Photolysis of NO2
• Harsh Odour• Bronchial
constriction• Coughing and
Wheezing• Damage Plastics• Retard Plant
Growth• Decrease yield of
crop
• People with asthma and respiratory problems mostly affected by it.It’s 0.1 PPM concentration can reduce half of total photosynthesis
Peroxy acyl nitrate(PAN),and other related compounds
• Formed by reaction of NO2 with VOCs
• Eye and respiratory irritation
• Cause damage to proteins
• Was not detected until recognized in smog,Cause more damage to plants than ozone
Factors affecting Formation of Photochemical Smog
Formation of Different content of photochemical smog in different time of day
Pollutants are rinsed out of the atmosphere with rainfall
Photochemical Smog can be blown away by wind
Temperature Inversion increases photochemical smog
Role of Topography in smog formation
Mitigation measures
ForPhotochemical
Smog
Catalytic Converter
Free Radical Trap
Free Radical Traps
When Sprayed in the atmosphere
Produce Free
radical
Combine with free radical
O*,R*,RO* radicals
Free radical traps slows down the reaction
N2+O2→2NO
2NO+O2→2NO2
2-6 Hr
6-12 hr
Diethyl HYdroxylamine
Petrol reformati
on
1/10 Aromatic hydrocarbon
Oxygenated fuel
C(CH3)3OTertiary butyl
ether
Emission of oxides of Nitrogen is reduced
Petrol containing oxygenates atLow temperature
Emission of VOCs and NOxSupresess smog formation
How to save environmentby preventing Smog???!!!
i. Try to use the vehicles at minimal level and check the engine’s smoke emission frequently
ii. Prevent high usage of coals,which result in heavy smog
iii. Reduction of fumes from metal-working and other industrial plants;
iv. Buy green electricity-produced by low-or even zero-pollution facilities.
v. Reduce pesticide use.
vi. Consumers can reduce VOC emissions by avoiding paints with labels that clearly indicate VOC limits are high. Switching to water-based paint is also useful.
Lets start living and stop existingAnd save our mother earth
THANK YOU!!!