Air Pollution and Health PDF

Air Pollution and Health Prof Samuel Yu Health Safety & Environment Office Division of Environment and Sustainability HKUST Contents Different scales of air pollution impacts Health effects of common air pollutants What about Hong Kong? Air pollu...

Air Pollution and Health Prof Samuel Yu Health Safety & Environment Office Division of Environment and Sustainability HKUST Contents Different scales of air pollution impacts Health effects of common air pollutants What about Hong Kong? Air pollution control efforts in Hong Kong  PRS Q1, Q2 11/26/2024 Different Scales of Air Pollution Impact Local Air Pollution Problem-- Smog Originally referred to smoke and fog in London (plus SO2 oxidized to sulfuric acid mist in smog) Now commonly refer to photochemical smog typically found in Los Angeles and other major cities, including Hong Kong Key Ingredients of Smog Ultraviolet in sunlight Hydrocarbons from internal combustion engines (e.g. methane, benzene) producing peroxyl & other free radicals Nitrogen dioxides NO2 h NO + O Oxygen and ozone O2 + O h O3 Photochemical Smog in Los Angeles Recent Smog in Beijing Other Cities too… Harmful Effects of Smog Respiratory disorder Eye irritation Damage to materials (e.g. rubber, plastic, paint, etc) Decreased visibility Acid precipitation (subsequent damages) Worsen by Thermal Inversion Temperature Inversion Worsen Ground Level Pollution Boundary of Heavy Smog in Beijing Dec 2016 The London Smog Disaster of December 1952 Cold weather, light wind, many coal burning Thick smog caused thermal inversion to stay in daytime Smoke plus moisture in fog caused seriously reduced visibility to a few meters Smog lasted for 5 days Estimated 12,000 premature deaths and illness to many others Deaths Related to Dec 1952 London Smog Incident Source: http://www.portfolio.mvm.ed.ac.uk/studentwebs/session4/27/greatsmog52.htm Regional Air Pollution Problem-- Acid Rain Sulfur and nitrogen oxides generated mainly from fossil fuel burning Further oxidation and transport in the atmosphere Return to ground in dry or wet acidic deposit (particles, mist, rain, snow, etc) Harmful Effects of Acid Rain Damage to vegetation Affect soil acidity and subsequent nutrient availability Affect pH of water bodies and subsequent impact on aquatic ecosystem Respiratory effects on humans and animals Damage to properties, cultural heritage Decrease atmospheric visibility Global Air Pollution Problem – Ozone Hole Tropospheric ozone: irritating, harmful Stratospheric ozone: absorb biologically harmful ultraviolet radiation (UV-B) Stratospheric ozone layer depleted by chlorofluorocarbons (CFC) Major CFC use: refrigerants, aerosol propellants, blowing agents, solvents Signs of shrinking of the ozone hole! https://www.youtube.com/watch?v=7bWQQWvJymc Harmful Effects of Ozone Hole Harmful ultraviolet light reaching surface of Earth Increase cataract Increase skin cancer Damage to phytoplankton Damage to plant Good News: Ozone Hole is Healing! A UN report announced in Jan 2023 the ozone hole over Antarctica will fully mend in about 43 years Over 35 years of international effort to stop producing chemicals that damage stratospheric ozone layer, since 1987 Montreal Protocol “Saving 2 M people every year from skin caner” according to UNEP Director Global Air Pollution Problem -- Green House Effect Green house: increase in wavelength of solar radiation after penetration of glass Earth average surface temperature of 15oC is maintained by green house effect of water vapor & carbon dioxide Human activities generate air pollutants which significantly increased green house effect leading to global warming Causes of Green House Effect Combustion of fossil fuels producing CO2 Deforestation reducing earth’s capability of photosynthesis which reduce CO2 Cropland produces methane Other Greenhouse Gases: N2O, Hydrochlorofluorocarbons (HCFC), etc August 2023: 419.68 ppm August 2022: 417.15 ppm Last updated: Sep 05, 2023 Historical CO2 Data (from Ice Core since 800,000 years ago) Global Warming Based on predictions of computer modeling Increase in global temperature by 1.5 – 5oC Precipitation decreases Sea level increases by 0.5 – 1.5m Flooding of many large cities alone the shoreline Drastic climate change Health Effects addressed in a separate lecture Health Effects of Common Air Pollutants Particulates Chemically complex: carbon, polycyclic aromatic hydrocarbons, silica, salt (NaCl), inorganic ions (sulphates, ammonium, nitrates), metals Temporal and spatial variations ‘Respirable’ fraction (PM10,