ESS 8.3 - Urban Air Pollution

describe the 3 sources of air pollutants

• nitrogen oxides

  • combustion of fossil fuels in vehicles, power plants, industrial facilities

  • formation of ground-level ozone and photochemical smog

• sulfur dioxide

  • burning of oil + coal in power stations, industrial processes

  • formation of acid rain + respiratory problems

• carbon monoxide

  • incomplete combustion of fossil fuels (vehicles and industrial machinery)

  • colorless, odorless

  • reduces oxygen delivery in human body

distinguish between the two particulate matters

PM2.5 - fine particles that penetrate into the lungs / can enter bloodstream

• sources - combustion processes, industrial processes, secondary formation from gas pollutants

• severe health risks (ie respiratory + cardiovascular)

PM10 - larger particles that cause respiratory issues

• sources - road dust, construction, mechanical processes

• affects upper respiratory tract

explain primary pollution

substances that are emitted directly from a source and have an immediate impact on air quality

• chemically active at point of release

• contribute directly to environmental + human health deg

• carbon monoxide

explain secondary pollution

form in the atmosphere through chemical reactions between primary pollutants

examples

• tropospheric ozone / bad ozone - interaction between nitrogen oxides and volatile organic compounds in the presence of sunlight

• acid rain - sulphur dioxide + nitrogen oxides with water vapor

describe air pollution management strategies with named examples [7]

• public transport expansion

  • expanding + improving public transportation systems = reduces # of private vehicles = lower emissions

  • bus rapid transit system in Colombia - reduce traffic congestion + air pollution by providing alternative to car travel

• electric public transit

  • reduce PT emissions

  • Shenzhen China - fully electrified bus fleet

• natural screens

  • rows of trees/shrubs planted along roads = trap pollutants + reduce spread to residential areas

  • green walls - vegetated walls on buildings = absorb pollutants, reduce heat, improve air quality

  • London has a lot of green walls = reduce pollution in traffic heavy roads + urban aesthetics

• trees + urban green space

  • filter pollutants, provide shade, reduce urban heat island, overall environmental quality

  • NYC Million Trees - aims to plant a million trees

• compulsory catalytic converters

  • devices fitted to exhaust systems to reduce harmful emissions (used widely in Europe)

• Low emission zones (LEZ)

  • access is restricted to specific vehicles that meet specific emission standards = encourages use of cleaner vehicles + reducing pollution

  • European cities (Berlin + Milan)

• Pedestrianised Town Centers

  • pedestrian-only zones = reduces car usage = lower emissions

  • promote healthier lifestyles + enhance urban liveability

explain acid rain

any form of precipitation that has been acidified by chemical reactions in the atmosphere

• primarily caused by release of sulfur dioxide and nitrogen oxide from human activities

• undergo reactions to create sulfuric acid + nitric acid

• falls to ground as acid rain

provide the chemical formula for the formation of nitric acid

2NO + O₂ (Nitrogen Monoxide + Oxygen) → 2NO₂ (Nitrogen Dioxide) → 2NO₂ + H₂O (Nitrogen Dioxide + Water) → HNO₃ + HNO₂ (Nitric Acid + Nitrous Acid)

provide the chemical formula for the formation of sulfuric acid

2SO₂ + O₂ (Sulphur Dioxide + Oxygen) → 2SO₃ (Sulphur Trioxide) → SO₃ + H₂O (Sulphur trioxide + Water) → H₂SO₄ (Sulfuric Acid)

describe the impacts of acid rain [5]

leaching of nutrients

• accelerates leaching of essential nutrients (calcium, magnesium, potassium) from soil = depletes nutrient availability = reduced soil fertility + neg plant growth/health

• stunted growth, weakened disease resistance, reduced agricultural yields

aluminium toxification

• increases solubility of toxic metals which can release into the soil = toxic for plant roots, disrupt ability to absorb water + nutrients

• reduced biodiversity

• can also impact freshwater environments = toxic for aquatic organisms = disrupt food chains + biodiversity

  • impaired gill function, respiratory difficulties, morality

  • weakened/deformed exoskeletons

foliage

• dissolves protective wax coating = susceptibility to diseases, pests, environmental stressors

• visible leaf discoloration, reduced photosynthetic capacity, premature leaf drop = weaken plants + trees over time

buildings + infrastructure

• corrosion of materials / gradual deterioration

• carbonate based stones (marble + limestone) - acid reacts to form calcium sulfate, which is more soluble + easily washed away = surface erosion

• increased maintenance costs, structural dmg, loss of cultural heritage

human health

• nitrate + sulfate particles = tissue dmg and lung inflammation

• reduces overall air quality + public health risk

explain urban air pollution and its impacts with a named example

New Delhi, India

• high popl growth numbers = more cars + constructions/industries = increased air pollution

• water conservation forces farmers to set crop stubble on fire = worsened air pollution

• geography - himalayas direct the smoke to delhi + weather - creates a warm air dome that traps the polluted air

• gov policies - halt construction + restriction of vehicle use

explain acid acid and its impacts with a named example

Taj Mahal

• marble erosion due to air pollution + acid rain = yellow sheen

• tried to implement emission limits but usually ignored

  • lots of smoke + untreated sewage