Introduction to Atmosphere and Air Pollution PDF

1 Module 1 Introduction to Atmosphere and Air Pollution Course: Instructor: Dr. Sailesh Narayan Behera Civil Engineering Department ...

1 Module 1 Introduction to Atmosphere and Air Pollution Course: Instructor: Dr. Sailesh Narayan Behera Civil Engineering Department  2 Overview of the Module Module 1: Four spheres of the Earth. Overview of the Earth’s atmosphere. Thickness of Earth’s atmosphere. Vertical structure of the atmosphere. Temperature and pressure. Layers of atmosphere. Definition of air pollution. Systems of air pollution. Philosophy of air pollution control. Classification of air pollutants. Classification of sources of air pollutants. Components of an air pollution system or air quality management. Challenges of managing air pollution system. The four spheres of Earth (Earth systems) 3 The four spheres of Earth (Earth systems) 4  5 Earth systems: The four spheres of Earth  LITHOSPHERE: The lithosphere contains all of the cold, hard solid land of the planet's crust (surface), the semi-solid land underneath the crust, and the liquid land near the center of the planet.  HYDROSPHERE: The hydrosphere contains all the solid, liquid, and gaseous water of the planet. It ranges from 10 to 20 kilometers in thickness.  ATMOSPHERE: The atmosphere contains all the air in Earth's system. It extends from less than 1 m below the planet's surface to more than 10,000 km above the planet's surface. The biosphere is the “life zone” of the Earth, and includes all living organisms (including humans), and all organic matter that has not yet decomposed. The four spheres of Earth (Earth systems) 6 The four spheres of Earth (Earth systems) 7 The four spheres of Earth (Earth systems) 8 The four spheres of Earth (Earth systems) 9 The four spheres of Earth (Earth systems) 10 The four spheres of Earth (Earth systems) 11 The four spheres of Earth (Earth systems) 12  13 Overview of the Earth’s atmosphere  14 Overview of the Earth’s atmosphere  15 Overview of the Earth’s atmosphere  16 Thickness of Earth’s atmosphere  Relative to size of the earth, the atmosphere is extremely thin.  90% of mass below 16 km.  Given that the earth’s diameter is 12,756 km, the atmosphere is about the thickness of the skin on an apple.  The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere.  The atmosphere of Earth creates pressure, absorbs most meteoroids and ultraviolet solar radiation, warms the surface through heat retention (greenhouse effect), and reduces temperature extremes between day and night (the diurnal temperature variation), maintaining conditions allowing life and liquid water to exist on the Earth's surface.  17 Thickness of Earth’s atmosphere Layers of Atmosphere (Thickness of the atmosphere) 18 o Temperature increases to 2000°C o But atmosphere is so thin (each two molecules of gases are ~1 km apart) o Includes the Ionosphere- creates Auroras and important for radio waves o Atmosphere becomes much thinner o Temperature decreases with altitude at 2°C/km o 19% of gases, but little water vapor o Contains Ozone Layer o Temperature increases with altitude at 1°C/km o 80% of atmospheric mass o Temperature decreases with altitude at 6°C/km o All weather occurs here  19 Vertical structure of the atmosphere  Gravity holds the atmosphere to the earth.  Consequently, the pressure for any area can be defined by the weight (force) of a vertical column of air over the area. Vertical profiles of pressure & temperature 20 Mean temperature and pressure vs altitude at 30°N Vertical profiles of pressure & temperature 21 Vertical profiles of temperature 22 Vertical profiles of temperature 23 Troposphere:  Temperature declines due to decreases in pressure causing decreases in the average kinetic energy.  Conceptually the molecules of air are moving around more slowly, causing temperature to decline.  This can be predicted mathematically. Stratosphere: Increasing temperature in the stratosphere:  Caused by ozone absorption of UV radiation. Mesosphere: Decreasing temperature in the mesosphere  Caused by decreasing ozone. Thermosphere: In the thermosphere:  Warming caused by absorption of UV radiation by O2.  24 Troposphere and Stratosphere Troposphere:  0 to 15 km altitude.  The lowest region of the atmosphere, where life & weather exist.  Temperature decreases with altitude.  Long-wave radiation emitted from Earth is absorbed by the atmosphere, the atmosphere becomes less dense with increasing altitude, less air to absorb.  Top of the troposphere is known as the tropopause Stratosphere:  15 to 50 km altitude.  Temperature increases with altitude.  Heating occurs because ozone (O3) absorbs ultraviolet radiation from the Sun.  Top of the stratosphere is known as the stratopause.  25 Mesosphere and Thermosphere Mesosphere:  50 to 90 km altitude.  Temperature decreases with altitude.  The lowest temperatures in the entire atmosphere are found at the mesopause during summer at high latitudes, 130 K (-226°F) can occur.  Top of the mesosphere is known as the mesopause. Thermosphere:  90 to 500 km altitude.  Temperature increases with altitude above 90 km, and is constant above 200 km.  This heating is due to absorption of solar radiation (wavelengths less than 0.2 microns) by molecular oxygen (O2).  The highest temperatures in the atmosphere can be found in the thermosphere, 2000 K can occur.  26 Vertical profiles of temperature  27 Air Pollution: Definition “Presence of any substances, solid, liquid or gas in atmosphere in such a concentration that may or may tend to be injurious to the humans, animals, plants, property or the atmosphere itself, is referred to as air pollution and the substance and the substance air as air pollutant” Key - words : “such a concentration” What is that Concentration ? Clean External Atmosphere + Addition Effects  28 Snaps of air pollution in cities  29 Snaps of air pollution in Delhi  30 Snapshot before and during HAZE in Singapore  31 Snapshot during and after HAZE in Shanghai  32 Overview of air pollution sources  33 Overview of air pollution sources  34 Air pollution effects on humans  35 Air pollution effects on humans Air pollution effects on humans 36  37 Diversified effects of air pollution  38 Sources of pollution and effects  39 Linking air pollution to effects  40 Short- and long-term effects of air pollution  41 Systems of Air Pollution TRANSPORT SOURCE: Industrial Stack RECEPTOR  42 Systems of Air Pollution  43 Systems of Air Pollution  44 Systems of Air Pollution  45 Systems of Air Pollution  46 Philosophy of Air Pollution Control  Reduction of pollutant(s) emission to a point such that no noticeable adverse effects associated with pollutant(s) exist.  To determine extent of reduction:  Understand / Established Linkages between sources and receptors using meteorology.  Understand / Establish safe air quality levels for receptors.  Air Quality Standards ~ to protect receptors: o Primary Health Standards. o Secondary Standards for vegetation/crops. o Sensitive area standards.  47 Challenges of Managing Air Pollution System  Problem 3-Dimensional.  Transport Medium beyond Control/regulation.  Impacts – Instant and Chronic.  Receptors Remediation almost Impossible.  Solution cannot be delayed. Types of Remediation: I. Medium Remediation. II. Source Remediation. III. Receptor Remediation.  48 Two basic categories of air pollutants 1) Criteria Pollutants: PM, SO2, NOx, and CO 2) Non- criteria Pollutants: Pb, Asbestos, Vinyl chloride, Mercury, Arsenic TOC (Trace Organic Carbon) and others How much external addition ? Develop the basis ~ Criteria Dose-Response/Cause – Effect Knowledge (receptor specific)  49 Criteria pollutants Criteria air pollutants' are air pollutants that have been regulated, continuously monitored and are used as indicators of air quality The Clean Air Act (CAA) of 1970 identified six common air pollutants of concern, called criteria pollutants. The criteria pollutants are:  Carbon monoxide (CO),  Nitrogen dioxide (NO2),  Sulfur dioxide (SO2).  Ozone (O3),  Lead (Pb),  Particulate matter, and  50 Criteria pollutants contd….. Formation of smog by NOx:  51 Criteria pollutants contd….. Ground-level Ozone (O3) What are photochemical oxidants and ozone? Photochemical oxidants are secondary air pollutants formed under the influence of sunlight by complex photochemical reactions in air which contains nitrogen oxides and reactive hydrocarbons as precursors. The most adverse components formed by photochemical reactions in polluted air are ozone (O3) and peroxyacetyl nitrate (PAN), among many other products such as aldehydes, ketones, organic and inorganic acids, nitrates, sulfates etc.  52 Criteria pollutants contd….. Ground-level Ozone (O3) Ozone makes up approximately 90% of the total photochemical oxidant pool. Other photochemical oxidants of concern in atmosphere are: Nascent oxygen [O] Excited molecular oxygen (O2) Peroxy-acetyl nitrate (PAN) Peroxy-propinol nitrate (PPN) Peroxy-butyl nitrate (PBN) Nitrogen dioxide (NO2) Hydrogen peroxide (H2O2) and Alkyl nitrates.  53 Criteria pollutants contd….. Ground-level Ozone (O3)  54 Criteria pollutants contd….. Ground-level Ozone (O3) Why is this time shown up here?  55 Criteria pollutants contd….. Comparison of PM10 and PM2.5 with human hair  56 Criteria pollutants contd…..  57 Hazardous Air Pollutants (HAPs) Hazardous air pollutants, also known as toxic air pollutants or air toxics, are those pollutants that cause or may cause cancer or other serious health effects, such as reproductive effects or birth defects, or adverse environmental and ecological effects. USEPA (under Clean Air Act of 1990) have identified 187 chemicals as HAPs. HAPs are more toxic than criteria pollutants; they “... may reasonably be expected to result in serious irreversible... disease, including cancer” You don’t find all 187 HAPs in environment, as they are specific to particular environments depending on what kind of industries are found in the surrounding area.  58 Hazardous Air Pollutants (HAPs) As it is difficult to control and talk about all of these chemicals, scientists have found out some 33 HAPs which are commonly found in the urban environment, where most of the people reside. Examples of HAPs Benzene, which is found in gasoline; Perchlorethlyene, which is emitted from some dry cleaning facilities; Methylene chloride, which is used as a solvent and paint stripper by a number of industries.  59 Hazardous Air Pollutants (HAPs) Sources of HAPs Most air toxics (HAPs) originate from human-made sources, including mobile sources (e.g., cars, trucks, buses) and stationary sources (e.g., factories, refineries, power plants), as well as indoor sources (e.g., some building materials and cleaning solvents). Some air toxics are also released from natural sources such as volcanic eruptions and forest fires.  60 Classification of pollutants All air pollutants may be classified according to origin, chemical composition and state of matter. 1. Based on Origin:  Primary pollutants: emitted directly to the atmosphere and found there in the form in which they were emitted. For example- sulfur dioxide (SO2), nitric oxide (NO), carbon monoxide (CO) and hydrocarbons (HC).  Secondary pollutants: formed in the atmosphere due to reactions (photochemical or hydrolysis or oxidation) amongst primary pollutants or other constituents of the atmosphere. For example- particulate matter (PM), sulfuric acid (H2SO4), Ozone (O3), peroxy-acetyl nitrate (PAN) etc.  Note that some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants. i.e. PM, NOx  61 Classification of pollutants All air pollutants may be classified according to origin, chemical composition and state of matter. 2. Based on Chemical composition:  Organic compounds: contain mainly carbon and hydrogen, but can contain elements such as oxygen, nitrogen, phosphorus, and sulfur as well. For example- hydrocarbons, aldehydes, ketones, carboxylic acids, alcohols, amines and organic sulfur compounds etc.  Inorganic materials: found in contaminated atmosphere include CO, CO2, carbonates, SOx, NOx, O3, hydrogen chloride (HCl) and hydrogen fluoride (HF) etc.  62 Classification of pollutants Chemical composition of PM2.5 and PM10 at Okhla, Delhi during winter and summer 2013-14.  63 Classification of pollutants 3. Based on State of matter:  Particulate pollutants: finely divided solids and liquids, include dust, fumes, smoke, fly ash mist, and spray. o Under proper conditions, particulate pollutants will settle out of the atmosphere under gravity.  Gaseous pollutants: formless fluids that completely occupy the space into which they are released, behave much as air and do not settle out of the atmosphere. E.g.- CO, CO2, SOx, NOx, and hydrocarbons (HC). Note that few pollutants such as polycyclic aromatic hydrocarbons (PAHs) are emitted both as gaseous and particulate based on their molecular weight, shape and vapor pressure.  64 Classification of pollutants  65 Components of an Air Pollution System (Air Quality Management)  66 Components of an Air Pollution System (Air Quality Management)  67 Components of an Air Pollution System (Air Quality Management)  68 Components of an Air Pollution System (Air Quality Management)  69 Components of an Air Pollution System (Air Quality Management)  70 Components of an Air Pollution System (Air Quality Management)  71 Air pollution as a stressor Normal intake: 13,5 kg indoor air Liquid 1,0 kg outdoor air 1,0 kg food Food 9% 1,5 kg liquid 6% Outdoor 6% Indoor, 5% transport Indoor, residential 53% 7% Indoor, industrial 14% Indoor, non- In Scandinavia: industrial 90-95% time indoors  72 References Sharma, M. (2014). Environmental Air Pollution. NPTEL and Swayam Portal. Daly, A., & Zannetti, P. (2007). An introduction to air pollution–definitions, classifications, and history. Ambient Air Pollution P Zannetti, D Al-Ajmi and S Al-Rashied, The Arab School for Science and Technology and The EnviroComp Institute, 1-14. SIERRA‐VARGAS, M. P., & Teran, L. M. (2012). Air pollution: Impact and prevention. Respirology, 17(7), 1031-1038. Mayer, H. (1999). Air pollution in cities. Atmospheric environment, 33(24-25), 4029-4037. De Nevers, N. (2010). Air Pollution Control Engineering. Waveland Press, USA. Anderson, H. R. (2009). Air pollution and mortality: A history. Atmospheric Environment, 43(1), 142-152. Berkner, L. V., & Marshall, L. C. (1965). History of major atmospheric components. Bickerstaff, K. (2004). Risk perception research: socio-cultural perspectives on the public experience of air pollution. 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