By
AKASH BISWAL
3rd Semester ,MSc
ENVIRONMENTAL
SCIENCE
DEPT-BOTANY

Name Industrial Smog Photochemical Smog
Weather Cool,Damp Sunny
Content Particulate,SO2 Nox,O3,Hydrocarbon
Chief Sourse Coal Combustion Gasoline Combustion
Smog
Industrial Smog
Or
London Smog
Photochemical Smog
Or
Los Angels 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 Pollutant
NOx , VOCs
Secondary Air Pollutant
Ozone(O3) , PAN

Process Involving Formation Of
Photochemical Smog

Formation of Oxides of Nitrogen
N2+O2→2NO
2NO+O2→NO2
NO2+hν→NO+O
Photolysis

Formation of Tropospheric Ozone
Nitrogen
Oxide
O∙+O2→O3
NO+O3→NO2+O2

O3+RH→RCO2
∙+RCHO+R2CO
Hydrocarbon
O+RH→R∙ + RCO∙ (acyl radical)
RCO∙ +O2 →RCO3
∙ (peroxyacyl radical)
RCO3
∙+ NO2 → RCO3NO2
R=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
concentratio
n of NO2
results From
combustion
and most is
formed from
reaction
involving NO
from
lightening,
Bacterial
action in soil.

Volatile Organic
compound(VOC
s)
 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
photosynthesi
s

Peroxy acyl
nitrate(PAN)
,and other
related
compounds
• Formed
by
reaction
of NO2
with
VOCs
• Eye and
respirato
ry
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
For
Photochemical
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
reformatio
n
1/10 Aromatic
hydrocarbon
Oxygenated fuel
C(CH3)3O
Tertiary butyl
ether
Emission of oxides of
Nitrogen is reduced
Petrol containing oxygena
Low temperature
Emission of VOCs and N
Supresess smog formati

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.