Smog is a mixture of fog and smoke prevalent in industrial cities, primarily classified into classical and photochemical types. Photochemical smog forms when ultraviolet light reacts with nitrogen oxides and volatile organic compounds, leading to harmful effects like respiratory issues and exacerbating asthma. Historical events like the Great Smog of London in 1952 highlight its severity, prompting suggestions for reducing smog through vehicle use minimization and the use of low-emission products.

2. What is Smog?
“Smog”
Is a mixture of
Fog and Smoke
Which occurs in some
Busy industrial cities
(Fog + Smoke = Smog)

3. Smog is of two types:
1. Classical Smog
2. Photochemical Smog
Here we will discuss about photochemical smog

4. Photochemical Smog
Photochemical smog is a type of
smog produced when ultraviolet
light from the sun reacts with
nitrogen oxides (NOx) and
volatile organic compounds
(VOCs) in the atmosphere
creating a brown haze above cities.

5. Composition of Photochemical Smog
The major undesirable components of photochemical smog are:
• Nitrogen dioxide (NO2)
• Ozone(O3)
• Peroxiacetylnitrate(PAN)
• Aldehydes

6. Formation Of Photochemical Smog
General Reaction:
NOx + VOCs Ozone + PAN
Mechanism:
NO2 + UV Radiation NO + O
O + O2 O3
Sunlight

7. NO + O3 NO2 +O2

8. Nitrgen Oxides (NOx) mostly comes from the
smoke of vehicles and trucks contact of this with
sunlight results
in the formation
of smog

9. Volatile Organic Compounds (VOCs) are
emmited as gases from solids or liquids VOCs include variety
of chemicals , some of
which may have long
and some term adverse
health effects . VOCs are
emmited by a wide range
of products numbering
in thousands .
Examples: Paints
pesticides, Glues and
adhesive materials etc.

10. It can cause anything from minor pain to deadly
deseases such as lungs cancer , wheezing . Smog
slowly ruins people’s lungs to an extent as great as that
of cigarettes.
Health Effects:

11. Smog can irritate and inflame
pulmonatery membranes , causing
chest pains , coughing and throat
irritation. Other illnessess such as
cold and pneumonia can also be
brought on by exposure to smog.
People with asthma problems are
under an even great threat. Even
minor exposure to smog may cause
these poeple to get asthma attacks .

12. The at Smog Of 52 or Big Smog was a severe pollution event that affected
London in December 1952. A period of cold weather combined with anti cyclone and
windless conditions collected airborne pollutants mostly from the use of coal to form a thick
layer of smog over the city. It lasted from Friday 5 to Tuesday 9 ,December 1952 and then
quickly dispersed after a change in the weather.
4000 had died and 100,000 were made ill due to effects of smog

13. How to save
environment by
preventing
smog?

14. 1. Try to use the vehicles at minimum level and check the
engine’s smoke emmissin frequently.
2. Prevent high usage of coal which results in heavy smog
3. Reduction of fumes from metal –working and industrial
plants.
4. Buy green electricity- produced by low or even zero
pollution facilities.
5. Reduce pesticides use.
6. Consumers can reduce VOC emmissin by avoiding paints
with labels that clearly indicate VOC limits are high.

15. Thank You!!!