6.3 Photochemical Smog

What does air pollution consist of?

What does air pollution consist of?

Primary pollutant, secondary pollutants

Define primary pollutant

Directly emitted from sources

Define secondary pollutant

Formed through chemical reactions in atmosphere

What are examples of primary pollutants?

• CO - harmful, odourless gas causing poisoning

• CO2 - greenhouse gas driving global warming

• Soot - from incomplete combustion, worsening air quality, climate change

• VOCs (Volatile Organic Compounds) - released during combustion, contributes to smog

• NOx - smog, respiratory issues

• SOx - lead to acid rain, health problems

What are examples of secondary pollutants?

• Tropospheric ozone (O3)

• Nitric acid (HNO3)

How is ozone formed?

Formed from reactions between O2 and NO2 under sunlight

How is nitric acid formed?

Formed from NOx, contributes to acid rain and particulate pollution

Why is it important to control pollutants?

• Reduce fossil fuel emissions to limit primary and secondary pollutants

• Promote cleaner technologies and air quality measures

• Mitigate health risks and environmental damage (e.g. acid rain, smog, climate change)

What is tropospheric ozone also referred to as?

Ground-level ozone

How are nitrogen oxides formed?

Industrial processes, vehicle emissions, combustion of fossil fuels

Why is ozone negative?

It is highly reactive and damaging

What are the effects of ozone on plants?

O3 absorbed by leaves

• Damage plant tissues, impair photosynthesis by degrading chlorophyll

• Reduce crop yields

• Leaf damage symptoms

Wheat, rice, soybeans

What are the effects of ozone on human health?

• Irritates respiratory system - coughing, throat irritation, asthma

• Reduced lung function with prolonged exposure to high ozone levels

• Eye irritation

What is the effect of ozone on materials?

• Can damage materials such as rubber, fabrics, certain plastics, cellulose

• Reduces car tires

• Bleaches fabrics

When is ozone good/bad?

• Good: provides organisms with protection from harmful UV radiation

• Bad: high concentrations

What are the 3 categories for reducing air pollution?

• Altering human activity producing pollution

• Regulating and reducing pollution at point of emission

• Clean up and restoration

How to alter human activity?

• Encourage energy-efficient technologies

• Promote use of public transport to reduce number of vehicles

How to regulate and reduce pollutants at point of emission?

• Government regulations to set emission limits

• Taxes/fees on high-polluting activities

• Cleaner, renewable energy sources