Untitled Quiz

Air Pollution and Health

• Air pollution has various scales and impacts human health.
• Common air pollutants have specific health effects.
• Hong Kong faces significant air pollution issues.
• Air pollution control efforts are ongoing in Hong Kong.

Different Scales of Air Pollution Impact

• Local air pollution problems include smog.
• Smog, originally smoke and fog in London with SO2 oxidation to sulfuric acid, is now commonly photochemical smog (Los Angeles, Hong Kong).
• Key ingredients of smog: ultraviolet light, hydrocarbons from combustion engines (methane, benzene), nitrogen dioxide (NO2), oxygen and ozone.

Harmful Effects of Smog

• Respiratory disorders
• Eye irritation
• Damage to materials (rubber, plastic, paint)
• Reduced visibility
• Acid precipitation (and its consequences)
• Thermal inversion worsens ground-level pollution

Regional Air Pollution Problem - Acid Rain

• Sulfur and nitrogen oxides, primarily from fossil fuel burning, cause acid rain.
• These oxides oxidize in the atmosphere and return to the ground as dry or wet acidic deposits (particles, mist, rain, snow).
• Acid rain damages vegetation, affects soil acidity, impacts water bodies, and harms aquatic ecosystems, human and animal respiration, and properties/cultural heritage.

Global Air Pollution Problem - Ozone Hole

• Tropospheric ozone is irritating and harmful.
• Stratospheric ozone absorbs harmful ultraviolet radiation (UV-B).
• The stratospheric ozone layer is depleted by chlorofluorocarbons (CFCs).
• Major CFC uses are refrigerants, aerosols, propellants, and solvents.

Harmful Effects of Ozone Hole

• Harmful ultraviolet light reaching Earth's surface
• Increased cataracts
• Increased skin cancer
• Damage to phytoplankton
• Damage to plants

Good News: Ozone Hole is Healing!

• A UN report (Jan 2023) indicates the ozone hole over Antarctica will fully mend in about 43 years.
• Over 35 years of international efforts to stop damaging chemicals (since 1987, Montreal Protocol) have achieved this positive trend.

Global Air Pollution Problem - Green House Effect

• Greenhouses increase wavelength of solar radiation after glass penetration.
• Earth's average surface temperature of 15°C is maintained by the greenhouse effect of water vapor and carbon dioxide.
• Human activities generate air pollutants that significantly increase the greenhouse effect, leading to global warming.

Causes of Green House Effect

• Combustion of fossil fuels produces CO2.
• Deforestation reduces Earth's photosynthesis capacity, affecting CO2 levels.
• Croplands produce methane.
• Other greenhouse gases include N2O and hydrochlorofluorocarbons (HCFCs).

Historical CO2 Data

• Ice core data shows CO2 levels before 1958. Mauna Loa data shows levels from 1958 onward.

Global Warming

• Computer modeling predicts a global temperature increase of 1.5 - 5°C.
• Precipitation patterns will change (reduce).
• Sea levels will rise by 0.5 - 1.5 meters.
• Coastal flooding of large cities is expected.
• Drastic climate shifts are likely.

Health Effects of Common Air Pollutants

• Particulates: Chemically complex (carbon, polycyclic hydrocarbons, silica, salt, inorganic ions, metals); exhibit temporal and spatial variations; respirable fractions (PM10, PM2.5, ultrafine); lead is from fuel additives, mining, incineration.

• Lead (Pb) poisoning affects kidneys, liver, brain, central nervous system and reproductive system. Low intake may affect mental development in children and cause anemia, headache, and sore muscles. Symptoms include fatigue and irritability.

• Sulfur Dioxide (SO2) exists as impurities in fossil fuels, turning into an oxide during combustion. It causes respiratory irritation, burning sensation, sore throat, and coughs. It mainly affects upper respiratory tract.

• Nitrogen Dioxide (NO2) formed by O2 & N2 at high temperature, causes respiratory issues, burning sensations, sore throats, and coughs; it is less soluble than SO2, penetrates deep into lungs; high concentration can cause lethal edema; chronic exposure causes emphysema, weakens immune.

• Ozone (O3) formed by photochemical reactions. It causes respiratory irritation, burning sensations, sore throats, and coughs. It penetrates deep into lungs, high concentrations may cause lethal edema; chronic exposure results in lung fibrosis and damage to lung functions.

• Carbon Monoxide (CO) product of incomplete combustion, highly toxic, prevents oxygen transport, chronic exposure affects nervous and cardiovascular systems, suspected to cause reproductive effects, such as neurological problems, low birth weight, increased stillbirths, and congenital heart problems.

• Volatile Organic Compounds (VOCs) (Petrochemicals) cause nausea, weakness, irritability. Chronic exposure may harm nervous systems, liver, and kidneys; some VOCs are human carcinogens or animal carcinogens.

What About Hong Kong?

• High population density, high traffic volume (9.7 million passenger journeys daily by public transport in 2022), densely packed roads with high density of cars (365 vehicles per km in 2023, compared to 77 UK, 38 US, and 19 China).
• Lack of city planning. Proximity to Pearl River Delta (rapid development).

Air Pollution Control Efforts in Hong Kong

• Air Quality Objectives: objectives outlined for 7 pollutants (SO2, NO2, CO, photochemical oxidants (O3), lead, total suspended particulates, and respirable suspended particulates).
• Licenses to Control Emissions: emissions from 30 specific processes (power plants, incinerators, concrete batching plants) regulated.
• Power Plants: emission caps on SO2, NO2 and respirable suspended particulates applied, emission allowances allocated according to electricity generation shares; power companies can trade allowances to meet emission caps.
• Vehicles: New registration compliant with EU, US, and Japan standards; specifications for motor vehicle fuels; emission reduction devices for diesel vehicles specified and enforced.
• Alternative Fuels: Promotion of LPG (liquefied petroleum gas) taxis and minibuses. Methods of vehicle fuel vapor recovery.
• Electric Vehicles: Tax waivers, funding for purchase of electric vehicles, including buses; phase-out schedule for petrol and hybrid vehicles determined.
• Other Initiatives: Energy saving campaigns, renewable energy (wind), pollution trading, restrictions on polluting industries, less polluting vehicles (hybrids, EURO IV, electric).
• Looking Ahead: Multi-year plan to further reduce air pollution by local and regional means. Announced in 2013, a cross-bureau effort with a 2017 progress report.
• Main Focus: Improving roadside air quality through upgrading diesel commercial vehicles, replacing catalytic converters, using LPG vehicles, implementing low-emission zones, emphasizing cleaner fuels for ocean-going vessels, and coordinated reduction plans with Guangdong.
• Major Goals and Actions (2013-2017): Implemented a new Air Quality Health Index (AQHI), implemented new air quality objectives (AQOs), enhanced public information (through website, mobile apps, public education), improved air monitoring, and shows reduction in air pollutants (SO2, NO2, PM10).