GEN S109F/1009SEF L6 Air Pollution I PDF

GEN S109F/1009SEF Environment and Health Lecture 6 Air Pollution and Control I Autumn 2024 https://www.youtube.com/watch?v=dL7mVD9g0rU 2 Learning Outcomes At the end of this lecture, you should be able to,  Understand the composition of air  Describe the concept of air pollution, its sour...

GEN S109F/1009SEF Environment and Health Lecture 6 Air Pollution and Control I Autumn 2024 https://www.youtube.com/watch?v=dL7mVD9g0rU 2 Learning Outcomes At the end of this lecture, you should be able to,  Understand the composition of air  Describe the concept of air pollution, its sources and its impact on human health and the environment  Recognize the concept of air pollution meteorology  Understand the concept of indoor air quality pollution 3  Earth’s atmosphere Atmosphere is a layer or a set of layers of gases surrounding the planet Earth Atmosphere layers start from the ground to all the way up in space These layers include: Troposphere Stratosphere (includes ozone layer) Mesosphere Thermosphere Exosphere Troposphere contains about 75% of all the air in the atmosphere, and almost all of the water vapor (which forms clouds and rain) 4  Air Air is one of the essential factors making life on the Earth possible Carbon Other gases Composition of air Argon dioxide and water 0.93% 0.04% vapor 0.03% Oxygen 21% Human consumes between 6 – 13 cubic meters of air daily Nitrogen 78% 5  Atmospheric air Source: Sorbjan, Z. (2003) Air-Pollution Meteorology. Chapter 4 of AIR QUALITY MODELING - Theories, Methodologies, Computational Techniques, and Available Databases and Software. Vol. I - Fundamentals (P. Zannetti, Editor). Published by The EnviroComp Institute (http://www.envirocomp.org/) and the Air & Waste Management Association (http://www.awma.org/). 6  Air pollution According to World Health Organization (WHO), "an increase in any of the constituents of the atmosphere which is harmful to living beings and their environment, is known as air pollution" Sometimes, polluted air is visible or can be smelled. For example, black smoke emitted from the factory Some of the major pollutants, e.g. carbon dioxide, are invisible and odorless 7  Why air pollution is an issue Video: ”Air Pollution 101 | National Geographic”, https://www.youtube.com/watch?v=e6rglsLy1Ys 8  Why air pollution is an issue Air pollution causes adverse effects on human and the environment For examples, Health problems in human Damage to plant and agriculture Global climate change Reduction in visibility… 9  Why air pollution is a global concern Air pollution is the 4th largest threat to human health (behind high blood pressure, dietary risks and smoking) According to WHO, air pollution kills an estimated of 7 million people worldwide every year WHO data shows that 9 out of 10 people breathe air containing high level of pollutants 10  Sources of air pollution Natural source Man-made source Volcanic eruption (sulphur, chlorine and ash “Stationary sources” include smoke stacks of power particulates) plants, industries, and waste incinerators, as well as Forrest fire furnaces and other types of fuel-burning heating Dust from natural sources, usually large devices areas of land with little or no vegetation Mobile sources include motor vehicles, marine etc. vessels and aircraft etc. Controlled burn practices in agriculture and forestry management Fumes from paint, hair spray, varnish, aerosol sprays and other solvents Landfills Military practices etc. 11  What are the sources of air pollution? https://www.youtube.com/watch?v=JmIYD6qjQ-k&t=196s 12  Air pollutants “Airborne substances (either solids, liquids, or gases) that occur in concentrations high enough to threaten the health of people and animals, to harm vegetation and structures, or to toxify a given environment” 13  Classification of pollutants According to origin Primary pollutants: Emitted directly into the atmosphere and are found in form in which they are emitted e.g., carbon monoxide, nitrogen oxide (NOx), sulfur dioxide (SO2), particulate matter (PM), etc. Secondary pollutants: Derived from the primary pollutants by chemical or photo-chemical reactions in the atmosphere e.g., Ozone (O3) formed by the Sun’s UV light on nitrogen oxides Sulfuric acid (H2SO4) derived from sulfur dioxide (SO2, primary pollutant) Nitric acid (HNO3) derived from NOx (primary pollutant) 14  Classification of pollutants Video: “Air Pollution (Animation) https://www.youtube.com/watch?v=jtiANpcpJJY 15  Classification of pollutants According to state of matter Gaseous: Carbon monoxide (CO), sulfur dioxide (SO2), nitrous oxide (NO) and nitrogen dioxide (NO2), benzene, methane Particulates/aerosols: Solid: dust, fly ash aerosol: Liquid: mist, spray Suspension of fine solid particles or Biological substances: pollen, spores liquid droplets in Particulate: air/gas Microscopic particles of solid/liquid Suspended in air 16 Major sources and principal effects of some common air pollutants 17  Sulfur dioxide (SO2) Physical properties Colorless gas with irritating, pungent odor; detected by taste at 0.3 – 1 ppm (v/v); very soluble in water Major sources Fuel combustion (coal, oil, cellulose material) through human Industrial processes such as metal and activity petroleum refining Natural sources Atmospheric oxidation of organic sulfides Principal effects Sensory and respiratory irritation Plant damage Potential health effects Contribution to acid deposition problems 18  Oxidant ozone Physical properties Colorless toxic gas; slightly soluble in water Major sources Atmospheric photochemical reactions involving through human nitrogen oxides, organic vapors and solar radiation activity Natural sources Natural atmospheric chemistry Transport from upper to lower atmosphere Principal effects Sensory and respiratory irritation Plant damage Reduced visibility through formation of photochemical aerosols Adverse health effects Material damage (e.g. polymers) 19  Carbon monoxide (CO) Physical properties Colorless, odorless, flammable gas and slightly soluble in water Major sources Transportation through human Fuel combustion for space heating and industrial process activity Natural sources Atmospheric oxidation of methane and other hydrocarbons of biological origins Principal effects Reduction in oxygen-carrying capacity of the blood Toxic at high concentration 20  Non-methane hydrocarbons Volatile Organic Compounds (VOCs) Major sources Transportation through human Fuel combustion activity Industrial process Solvent evaporation Natural sources Vegetation (e.g. pine forest) Principal effects Visibility reduction Plant damage Sensory irritation Contribution to photochemical pollutant formation 21  Nitrogen oxides (NOx) Physical properties NO2 (nitrogen dioxide) is a reddish brown gas with a sharp odor; toxic and corrosive, giving an acid gas in solution; absorbs light over much of the visible spectrum NO (nitrogen oxide) and N2O (nitrous oxide) are colorless, odorless gases, only slightly soluble in water Major sources through Transportation human activity Fuel combustion Industrial processes Natural sources Bacterial action produces NO and NO2 Natural combustion and lightning Principal effects Visibility reduction Plant damage Sensory irritation through formation of photochemical pollutants Direct health effects of nitrogen dioxide Global warming and acid deposition 22  Carbon dioxide (CO2) Physical properties Colorless, odorless, and moderately soluble in water giving an acid solution Major sources Combustion through human activity Natural sources Natural combustion Respiration Principal effects Global warming 23  Hydrogen fluoride Physical properties Colorless gas dissolving in water to give an acidic solution; highly toxic Major sources Heating to high temperatures certain ores, clays through human or fluxes containing fluorine, e.g. in steel, activity ceramic, aluminum and superphosphate fertilizer manufacture Principal effects Damage to plants Weakens teeth and bones of livestock grazing on forage contaminated by atmospheric fluoride 24  Lead Major sources Vehicles using leaded petrol through human Industrial emissions activity Principle effects Interference with metabolic processes Toxic in high doses 25 Particulate matter (PM) Major sources Industrial processes through human Automobiles activity Natural Wind sources Sandstorm Forest fires Volcano eruption 26  Particulate matter (PM) Health problems Respiratory effects caused by large concentrations of particles < 1 m, and fibrous particles such as asbestos Toxicity caused by components such as fluorides, lead, cadmium, beryllium etc. Eye or skin irritation caused by acid mists or small particles Aesthetic problems Soiling by large mass emission rates, tarry or sticky emissions Low visibility caused by small particles < 1 m which cause great light scattering Odor Economic problems Material damage caused by corrosive particles Cleaning costs related to soiling Secondary economic problems caused by neighborhood deterioration Toxicological aspects Particulate matter may be toxic through: (1) Intrinsic toxicity of the particles (2) Interferences with clearance mechanisms of respiratory tract (3) Particles carrying toxic substance 27 Effects of air pollution 28  Air pollutants: Source, properties and harmful effects https://www.youtube.com/watch?v=caZekR5Cc0c 29  Effects of air pollution on human health Asthma Respiratory problems Cancer Heart disease Birth defects Brain damage Damage to immune system Premature deaths etc. 30  Effects of air pollution on human health https://www.youtube.com/watch?v=GVBeY1jSG9Y 31  Effect on atmospheric properties Air pollutants affect atmospheric properties in the following ways: Reduction in visibility Smog formation Reduction in solar radiation Alteration in temperature and wind direction Global climate changes 32  Effect on vegetation Damage on the leaves of the plant Necrosis (dead areas of leaf) Chlorosis (loss or reduction of chlorophyll causing yellowing of leaf) Epinasty (Downward curling of the leaf) Leaf abscission (dropping of leaves) 33  Effect on vegetation Air pollutants can enter the plant’s body through stomata (leaf pores through which gases diffuse) and destroy the chloroplast, thereby affecting photosynthesis This affects the crop yield Figure adapted and modified from https://doi.org/10.3389/fpls.2017.01318 34  Effect on vegetation Air pollutants erode the waxy coating of the leaves (cuticle) that prevents excessive water loss and damage from diseases Particulates deposited on leaves can plug the stomata (Blocking the gas exchange and also affecting transpiration) Particulates can reduce the availability of sunlight which is necessary for photosynthesis in plants Figure adapted and modified from https://doi.org/10.3389/fpls.2017.01318 35  Effect on materials Corrosion (e.g. on steel) by the action of acidic air pollutants Shortening of lifespan of organic materials (e.g., rubber, plastics and paints) by ozone, chlorine and nitrogen oxides 36  Economic consequences of air pollution Air pollution has been the 4th leading risk factor for premature deaths globally One out of ten deaths in 2013 was caused by diseases associated with air- pollution The problem is even more severe in the developing world These deaths cost the world economy over US$225 billion in labor productivity losses 37  Major phenomenon caused by air pollution 1. Global warming/ climate change (accelerated by greenhouse effect) 2. Acid rain 3. Ozone layer depletion 38  Air pollution meteorology Meteorology – The science of the Earth’s atmosphere Air pollution meteorology – Study of the connection between air pollution and atmospheric conditions Air pollutants are emitted from the source to the atmosphere Meteorological conditions determine how the air pollutants will disperse, transport, dilute, diffuse or mix in the atmosphere Air pollution meteorology concerns about: (1) the effects of atmospheric conditions on the fate and transportation of the air pollutants (2) the effects of pollutants on meteorology 39  Fate and transportation of the air pollutants Wet deposition (pollutants fall through the atmosphere in the form of rain, fog etc.) Dispersal of the pollutants Cloud Some pollutants may be converted into new compounds Dry via chemical transformation deposition (Gaseous Deposition compounds or aerosol deposited on land/aquatic surface) Emission of air pollutant (Source) 40 Effects of atmospheric conditions on the fate and transportation of the air pollutants Meteorological factors that affect the fate and transport of air pollutants: Primary factors Wind direction and speed Atmospheric temperature Atmospheric pressure For all these factors the deriving force is SUN or SOLAR ENERGY Secondary factors Precipitation (Rainfall) Humidity Solar radiation These parameters varies widely as a function of latitude, seasons, and topography 41 Meteorological factors that affect the fate and transport of air pollutants Wind direction Determines the migration direction of the air pollutant Wind speed Affects the dispersal of air pollutants Diluting effect of pollutants by wind speed (A) (B) Doubling the wind speed halves the pollutant concentration for a given emission rate 42 Meteorological factors that affect the fate and transport of air pollutants Atmospheric temperature Affects the movement of air pollution Convection Cool, dense air Warm air Cool air sinks downward Molecules Molecules move and pushes warm move faster slower Molecules are Molecules are air out of the way farther apart closer together Warm air carries Warm air is Cool air is more energy upward less dense dense Radiation Sunlight warms the ground Conduction The warm ground heats the air 43 Meteorological factors that affect the fate and transport of air pollutants Land and sea breezes play an important role in transporting air pollution from urban areas on the coast 44 Meteorological factors that affect the fate and transport of air pollutants Atmospheric temperature Vertical temperature profile (Change of temperature with height in the atmosphere) affects the accumulation and dispersal of air pollutants Normally, the increase in latitude, the lower the temperature Temperature inversion: Temperature increases with height Inversion layer act as a lid and trap air pollutants near the Earth’s surface Warm air – inversion layer 45 Meteorological factors that affect the fate and transport of air pollutants Video: “Temperature Inversions”, https://www.youtube.com/watch?v=Dk9VHHFUbqo 46 Meteorological factors that affect the fate and transport of air pollutants Atmospheric temperature Temperature affects the chemical transformations of pollutants For example, warm temperature favors the formation of photochemical ozone 47 Meteorological factors that affect the fate and transport of air pollutants Atmospheric pressure Air flows up at a low Rising air Descending air Air near the surface flows down and pressure system away in a high pressure system 48 Meteorological factors that affect the fate and transport of air pollutants Atmospheric pressure It affects air movement as air moves due to difference in air pressure between different locations The difference in air pressure is in relation to temperature (Warmer the place, lower the pressure; cooler the place higher the pressure) Air pressure relates to the atmospheric stability High pressure system generates stagnant air, inhibiting the pollutant dispersion and trapping the air pollutants over an area Low pressure system results in wet and windy condition, which facilities the transport of pollutants to a new area 49 Meteorological factors that affect the fate and transport of air pollutants Precipitation/ rainfall Washing air pollutants away => can clean the air Leads to wet deposition of air pollutants => Impacts on water and soil quality as well as vegetation 50 Meteorological factors that affect the fate and transport of air pollutants Humidity Humidity refers to the water vapour content of air It associates with the thermal and photochemical reactions in the atmosphere Water can attach to the particles suspended in the air, increasing the amount of light scattering of the particles => Reduction in visibility Corrosive gases (e.g., SO2) may dissolve in the atmospheric water and form acid solution => Acid rain 51 Meteorological factors that affect the fate and transport of air pollutants Solar radiation (sunlight) Relates to the chemical transformations that occur in the atmosphere to form photochemical smog from the pollutants Radiation 52 Meteorological factors that affect the fate and transport of air pollutants Solar radiation (sunlight) photochemical ozone 53  Typhoon and air quality https://www.youtube.com/watch?v=53xsRH6DJ04&list=PLKDQ-7M3dvXYtKMoo8JCU05RzFUpWX0yG&index=8 54 Sources, transport and fate of air pollutants 56  Effects of air pollutants on meteorology Global warming/climate change Acid rain Ozone layer depletion Ozone hole 57  Global warming The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat Major greenhouse gases include:  CO2  Methane  N2 O Emission of greenhouse gases enhance the greenhouse effect Enhanced greenhouse effect is increasing Earth’s temperature, resulting in global warming Consequences of global warming:  Climate change  Flooding due to extreme climate  Melting of ice cap => Rise in sea level  Alteration in ecosystems 58 Common GHGs 59  Global warming potential  Global-warming potential (GWP): a relative measure of how much heat a greenhouse gas traps in the atmosphere Relative GWP / CO2 Gas Formula (100 years) Carbon dioxide CO2 1 Methane CH4 25 Nitrous oxide N2O 298 Perfluorocarbons CnF2n+2 7,400 to 12,200 Hydrofluorocarbons CnHmFp 120 to 14,800 Sulfur hexafluoride SF6 22,800 61 61  Global warming https://www.youtube.com/watch?v=G4H1N_yXBiA 62 Global warming 63 https://www.youtube.com/watch?v=ifrHogDujXw Global warming 64 https://www.youtube.com/watch?v=Uf7vYkX-WVs  Consequences of global warming  Climate change  Flooding and droughts due to extreme climate  Melting of ice cap and a rise in sea level  Alteration in ecosystems 65  What is Climate Change?  Climate change: significant, long-term changes in the global climate  Connected system of sun, earth and oceans, wind, rain and snow, forests, deserts and savannas, and everything people do  Systemic connectedness makes global climate change so important and so complicated 66 46  Floods in Pakistan Typhoon Mangkhut Hurricane Maria 67  Visual Impacts of Climate Change Melting Glaciers Rising Sea Levels Flooding https://warmheartworldwide.org/ Worsening Droughts Supercell Storms Increasing Tornados 68  Other effects of global warming  Impact on staple crops  Reduced by up to 22% by 2050 due to ground level ozone and global warming, expected to go up to 40% in South Asia  Ocean acidification  CO2 addition  Due to reduced mixing in sea water  Vicious cycle for carbon concentration 69  Global GHGs emissions Annual GHGs emissions GHGs by gas type and source 70 GHGs emissions by country 71 GHGs emissions in Hong Kong Sector % of the Total Emissions Electricity Generation 69.3 Transport 17.2 Other End Use of Fuel 4.9 Waste 5.3 Industrial Processes 3.2 and Product Use Agriculture, Forestry 0.1 and Other Land Use https://www.polyu.edu.hk/ 72 Global climate change 73 GHGs emissions and warming scenarios 74  Acid rain  Acid rain, or acid deposition, is a broad term that includes any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms  This can include rain, snow, fog, hail or even dust that is acidic  Acid rain occurs when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents  The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids  These then mix with water and other materials before falling to the ground 75  Acid rain https://www.youtube.com/watch?v=1PDjVDIrFec 76  Consequences of acid rain Adverse effects on human: Irritation to eyes, nose, throat Respiratory symptoms such as bronchitis and asthma Adverse effects on the environment: Ocean acidification => Damage to aquatic ecosystems Increase of soil acidity Damage to materials (e.g., buildings and statues) 77  Ozone layer depletion  Ozone layer is the region of the upper atmosphere, between roughly 15 and 35 km above Earth’s surface, containing high concentrations (90% of the atmosphere’s ozone ) of ozone molecule  The ozone layer effectively blocks almost all solar radiation of wavelengths less than 290 nm from reaching Earth’s surface that could injure or kill most living things  Since about 1975, scientists have detected a severe drop in ozone concentration in the layer over the Antarctica  In 1987 an international expedition found that half of the Ozone hole Antarctica's ozone have disappeared over a region twice the size of the United States, creating an enormous "hole" in the ozone layer.  Concentrations of ozone fell by as much as 50% 78  Ozone layer depletion Video: “limate 101: Ozone Depletion | National Geographic” https://www.youtube.com/watch?v=aU6pxSNDPhs 79  Ozone layer depletion Chlorofluorocarbon (CFC) Cl + O3 -> ClO + O2 80 Indoor air quality pollution 81  Indoor air quality Indoor air quality refers to the quality of air in enclosed spaces, such as home, school or workplace In enclosed spaces, dilution and dispersion of air pollutants are limited, especially nearest the source Indoor air quality is more detrimental to human health than to the environment because people spend a lot of their time indoor According to WHO, 7 million people are killed by air pollution Annually and ~4 million of premature deaths are due to indoor exposure to air pollutants 82  Common indoor air pollutants Physical pollutants Fine particles (e.g., PM 2.5) Dust 83  Common indoor air pollutants Biological contaminants Dust mite Pollen Mould Bacteria Virus Sources: Carried by people, animals, soil and plant debris; poor ventilation system Effects: Hypersensitivity; harmful/toxic to human 84  Common indoor air pollutants Chemical pollutants Volatile Organic Chemicals (VOC) e.g., Formaldehyde, benzene etc. Sources: Effects: Furniture Eye, nose and throat irritation Paints Dizziness, headaches Cleaning products Breathing difficulties Cigarette smoking Skin irritation 85  Indoor air pollutant Chemical pollutants Cigarette smoke Carbon monoxide Source: Smoking Source: smoking, malfunctioning Contains formaldehyde, carbon monoxide furnace, gas appliances, cars and toxic substances Effects: Blood cannot carry oxygen, Causes lung cancer and emphysema nausea, dizzy and fatal 86  Indoor air pollutant Chemical pollutants Radon Asbestos Radioactive gas with no taste, smell nor Sources: Roofing, flooring, insulation, color brakes Sources: From soil under basement Effects: Cause asbestosis (scarring of Effects: Long term exposure can cause lung lungs) and mesothelioma (Lung cancer) cancer 87  Indoor air pollutant Chemical pollutants Carbon dioxide Ozone Source: Human breathing, combustion Sources: machines that generate UV light or Effects: high voltage can cause ionization of air to No significant health impact but serves as form O3 an indicator of sufficient ventilation, e.g., photocopiers, laser printers, fax indicator of less oxygen machine Effects: Respiratory problems, headaches, loss of coordination, nausea, organ damage, cancer 88 Indoor air quality (IAQ) management 89  Improving indoor air quality (1) Source control Most effective way to improve indoor air quality is to eliminate individual sources of pollution or to reduce their emissions In many cases, source control represents a more cost-effective approach for having good indoor air quality Some examples for source control: Seal or replace asbestos Get rid of curtains, carpets and other materials which can absorb pollutants Changing personal habits, e.g., stop smoking 90  Improving indoor air quality (2) Improved ventilation Increasing the amount of outdoor air coming indoors helps lowering the concentrations of indoor air pollutants Opening windows and doors increases the outdoor ventilation rate Use of exhaust fans also promotes ventilation 91  Improving indoor air quality (3) Use of air cleaners Air cleans help removing particle They are generally not designed to remove gaseous pollutants 92  Indoor air pollution in Hong Kong Household air pollution in Hong Kong is severe Levels of VOCs that evaporate easily at room temperature were on average over 1,250% higher in kitchen than outdoors Indoor levels of PM2.5 and 10 were higher than outdoor The pollution is more serious in subdivided flats with a lack of window and ventilation and restaurants occupying ground-floor premises in residential buildings Source: South China Morning Post 93  IAQ Management Programme in Hong Kong In 2000, the Hong Kong Government implemented an IAQ Management Programme to improve IAQ and promote public awareness of the importance of IAQ In 2003, voluntary IAQ Certificate Scheme for Offices and Public Places were launched to recognize good IAQ management practices and motivate the owners of premises/buildings or property management companies to achieve the best level of IAQ 94  IAQ Management Programme in Hong Kong Video: “A11 Indoor Air Quality (English version)”, https://www.youtube.com/watch?v=84PHz-PiuVM 95  IAQ Certification Scheme https://www.iaq.gov.hk/en/iaq-certification-scheme/ 96  IAQ guidance notes Guidance Notes for the Management of IAQ in A Guide on IAQ Certification Scheme for Offices Offices and Public Places and Public Places Set out the general guidance on the Step-by-step guidance on how to participate in management of IAQ the certification scheme https://www.iaq.gov.hk/en/iaq-certification-scheme-references-and-useful-forms/ 97 IAQ objectives for offices and public places 98  Ordinances and regulations related to IAQ Building (Planning) Regulations and Building (Ventilating Systems) Regulations, under the Buildings Ordinance, CAP 123 Ventilation of Scheduled Premises Regulation, under the Public Health and Municipal Services Ordinance, CAP 132 Places of Public Entertainment Regulations, CAP 172 Air Pollution Control Ordinance, CAP. 311 Smoking (Public Health) Ordinance, CAP 371 Consumer Goods Safety Ordinance, CAP 456 Ozone Layer Protection Ordinance, CAP 403 Pesticides Ordinance, CAP 133 Occupational Safety & Health Ordinance, CAP 509 99