1. And its Environmental Effects
SMOG
And its Environmental Effects

2. History of Smog Name comes from a mix of “Smoke” and “Fog”
First observed in London during the industrial revolution
There are 2 types of smog: Industrial Smog (London) and Photochemical Smog (Los Angeles)

3. Industrial Smog (Reducing)
Source: Pollution from the burning of coal and oil that contains sulfur
Consists mainly of: Sulfur Dioxide, Sulfur Trioxide, soot and ash (particulate matter) and sulfuric acid
It can cause breathing difficulties in humans, plus acid rain damage to plants, aquatic systems, and metal or stone objects
London and Chicago have problems with industrial smog.
Methods of reducing this smog: Alkaline Scrubbers reduce SO2 and SO3 levels; electrostatic precipitators reduce particulates.

4. Photochemical Smog (Oxidizing)
Source: Mainly automobile pollution
Contains: Nitrogen Oxides, Ozone, Alkanals, Peroxyacyl Nitrates (PANs), plus hundreds of other substances
Effects: PANs cause eyes to water and can damage plants, O3 irritates eyes and deteriorates rubber and plants, NOx causes acid rain.
First observed in LA in the 1940s, Manila and Mexico City also experience this kind of smog
Catalytic Converters change NO to N2, Lean burning engines reduce Nox, but create more CO and Hydrocarbons.

5. Reactions of Smog
Sulfur Dioxide can be oxidized to Sulfur trioxide, a secondary pollutant:
Metallic Particulates act as a catalyst for this reaction.
In addition, free radicals from NO2 also speed up the reaction:

6. Reactions of Smog
The formation of Secondary Pollutants in Photochemical Smog.
1. Formation of NOx:
2. Photo-Dissociation of nitrogen dioxide to produce oxygen atoms:

7. Reactions of Smog 3. Atomic oxygen forms Ozone:
4. Formation of organic free radicals:

8. Reactions of Smog
5. Formation of photochemical “soup” containing hundreds of chemicals including PANs:

9. Thermal Inversions Abnormal arrangement of air masses
A warmer layer of air is trapped between two layers of colder air
This causes pollutants to be trapped near the earth’s surface
Can form when hills or mountains stop horizontal winds, causing pollutants to collect over a city.
Warm air collects over the polluted air, acting as a lid to stop the pollutants from being dispersed.
In London, 1952, a thermal inversion lasting several days resulted in the deaths of several thousand people, most severely affecting the very old and young
Thermal inversions worsen any type of smog

10. Thermal Inversions Normal Conditions Thermal Inversion Cooler Air
Winds disperse pollutants worldwide
Warmer Air
Cooler Air
Warm air layer
Cool Air trapped at surface
Pollutants dissociate upwards
Pollutants trapped at surface
Normal Conditions
Thermal Inversion

11. Related Research

12. ANY QUESTIONS?