6.3 Photochemical Smog

Question 1

Temperature Inversion

Answer 1

Occurs when a layer of warmer air traps cooler air beneath it, preventing the dispersion of pollutants.

Question 2

Smog

Answer 2

A type of air pollution caused by the interaction of sunlight with pollutants like vehicle emissions, often resulting in a hazy, unhealthy atmosphere.

Portmanteau of smoke and fog!

Question 3

How is tropospheric ozone formed?

Answer 3

Nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight to produce oxygen radicals that react with oxygen molecules to form ozone (a secondary pollutant)

Question 4

Why is tropospheric ozone considered “bad” compared to stratospheric ozone?

Answer 4

Tropospheric ozone is a harmful pollutant causing respiratory issues, unlike stratospheric ozone which protects us from harmful UV radiation.

Question 5

How might geography (topography) affect pollution in cities.

Answer 5

Cities in valleys or basins can trap pollutants due to limited air circulation and frequent temperature inversions.

Question 6

Catalytic Converter

Answer 6

A device in vehicles that reduces harmful emissions by converting pollutants like NOx, carbon monoxide, and hydrocarbons into less harmful substances.

Question 7

Photochemical reaction

Answer 7

A chemical reaction triggered by sunlight, such as the formation of tropospheric ozone from pollutants (or photosynthesis).

Question 8

Effect of tropospheric ozone on humans

Answer 8

Causes respiratory problems, exacerbates asthma, and can lead to lung damage.

Question 9

Effect of tropospheric ozone on plants

Answer 9

Damages leaf tissues, reduces photosynthesis, and impairs growth and crop yields.

Question 10

Effect of tropospheric ozone on infrastructure

Answer 10

Accelerates the deterioration of materials like rubber and paints, leading to increased maintenance costs.

Question 11

Anthropocentric solutions to air pollution/photochemical smog

Answer 11

Focus on human-centered approaches like carpooling, reducing fossil fuel consumption, and promoting public transport.

Question 12

Ecocentric solutions to air pollution/photochemical smog

Answer 12

Emphasizes restoring ecosystems, planting trees, and adopting sustainable practices to naturally reduce pollutants.

Question 13

Technocentric solutions to air pollution/photochemical smog

Answer 13

Implementing advanced filtration systems (catalytic converters), electric vehicles

Question 14

Ways to reduce traffic congestion (Mexico City)

Answer 14

• driving only on certain days of the week (driving restriction program)
• working from home
• expanded public transport, and promotion of cycling.

Question 15

Cities where surrounding mountains trap air pollution

Answer 15

Los Angeles, Santiago, and Mexico City.

Question 16

Cities where temperature inversion traps pollutants.

Answer 16

Beijing, Denver, and Tehran frequently experience temperature inversions that trap pollutants close to the ground.

Question 17

What time of day is worst for photochemical smog?

Answer 17

Photochemical smog is usually the worst during the late morning (after morning rush hour) to early afternoon. This is because the formation of smog is driven by sunlight, which intensifies as the sun rises. As the day progresses and temperatures rise, these reactions peak, leading to the highest concentrations of smog typically around midday to early afternoon.

Question 18

PAN

Answer 18

PAN (Peroxyacyl Nitrates) are secondary pollutants formed by the reaction of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight.
Similar formation process and side effects to ozone.