Air Pollution and Control Engineering

AIR POLLUTION AND CONTROL ENGINEERING SUBJECT CODE: OCE551 R - 2017

UNIT - 1 INTRODUCTION • SYLLABUS Structure and composition of atmosphere – Definitions, scope and scales of air pollution –sources and classification of air pollutants and their effect on human health, vegetation, animals, property, aesthetic values and visibility – ambient air quality and emission standards.

INTRODUCTION • The clean air is very essential for human life and health. It should be free from pollutants in any form. The pollutants may be in the form of solid, liquid or gaseous form. Any considerable change in the composition of air may affect the living system of the humans. • Air pollution is defined as the pollution in the atmospheric air, due to the presence of solid, liquid or gaseous material and cause the problems to humans, living organisms, property, etc. • A pollutant is defined as a substance which creates the air pollution in the three states of matter which affects the atmospheric air considerably and creates harmful effects on the environment.

There are five layers in the structure of the atmosphere depending upon temperature. These layers are: • Troposphere • Stratosphere • Mesosphere • Thermosphere • Exosphere STRUCTURE OF THE ATMOSPHERE:

> 500 TO 190,000 KM 80 TO 500 KM OZONE LAYER

1. TROPOSHERE: • It is considered as the lowest layer of Earth’s atmosphere. • The troposphere starts at surface of the earth and goes up to a height of 12km. • All weather occurs within this layer. • This layer has water vapors and mature particles. • Temperature decreases at the rate of 1 degree Celsius for every 165 m of height. • Tropopause(Cold Trap) separates Troposphere and Stratosphere.

2. STRATOSPHERE: • It is the second layer of the atmosphere found above the troposphere. • It extends up to 50 km of height. • This layer is very dry as it contains little water vapour. • This layer provides some advantages for flight because it is above stormy weather and has steady, strong, horizontal winds. • The ozone layeris found in this layerand it absorbs UV rays and safeguards earth from harmful radiation. • Stratopause separates Stratosphere and Mesosphere.

3.MESOSPHERE: • The Mesosphere is found above the stratosphere. • It is the coldest of the atmospheric layers. • The mesosphere starts at 50 km above the surface of Earth and goes up to 80 km. • The temperature drops with altitude in this layer. • By 80 km it reaches -100 degrees Celsius. • Meteors burn up in this layer. • The upper limit is called Mesopausewhich separates Mesosphere and Thermosphere.

4. THERMOSPHERE: • Thermosphere is found above Mesopause from 80 to 500 km. • Radio waves which are transmitted from the earth are reflected back by this layer. • The temperature increases with height. • Aurora and satellites occur in this layer. IONOSPHERE: • The lower Thermosphere is called the Ionosphere and It is positioned between 80 and 500 km above the Mesopause. • Ionosphere consists of electrically charged particles known as ions. • This layer is defined as the layer of the atmosphere of Earth that is ionized by cosmic and solar radiation.

5. EXOSPHERE: • Exosphere is the outermost layer of the atmosphere. • In the exosphere, an upward travelling molecule moving fast enough to attain escape velocity which can escape to space with allowing the changes of collisions and so here molecules and atoms escape into space. • It extends from the top of the thermosphere up to 10,000 km.

NOTE: • The sun radiates its energy in all directions into space in short wavelengths, which is known as solar radiation. • The energy received by the earth’s surface in the form of short waves is termed as Incoming solar radiationor Insolation.

COMPOSITION OF ATMOSPHERE 1. GASES: • Carbon dioxide is a metalorgicallyvery important gas as it is transparent to the incoming solar radiation but opaque to the outgoing terrestrial radiation by absorbing the part of the it and reflects back towards the earth surface. The volume of other gases is constant, but the volume of this gas is rising in the past few decades. • Gases has also increased the temperature of atmospheric air. • Ozone is an another important component of the atmosphere, found between 10-50 kilometers above the earth surface. It acts as a filter and absorbs the UV (Ultra Violet) radiation from sun and prevents them from reaching the surface of earth’s atmosphere.

2. WATER VAPOUR: • It is also a variable gas in the atmosphere which decreases with altitude. When it is in warm and wet of tropics, it constitutes about 4% of the air by volume and similarly lesser than 1% of the air by volume when it is in the dry and cold regions of desserts and polar regions. • It also decreases from the equator towards the poles and it also absorbs the part of insulation from the sun and prevents the earth’s radiated heat. It acts like a blanket so as to maintain the atmospheric temperature to be neither too hot not cold and it also contributes in stability or instability of air. 3. DUST PARTICLES: • Atmosphere has the capacity to keep the small solid particles such as smoke, ash, sand, etc. on its surface.

Definition • Air pollution refers to any physical, chemical or biological change in the air. It is the contamination of air by harmful gases, dust and smoke. Them composition of gases present in the atmospherewhich gets collapsed . • Air pollution means the presence of chemicals or compounds in the air which are usually not present and which lower the quality of the air or cause detrimental(harmful) changes to the quality of life leading to the health risk(such as the damaging of the ozone layer or causing global warming).

Scope of air pollution • The scope of air pollution explained by the three associations were: 1) Engineering Built Council of USA 2) American Medical Association 3) Indian standard • The types of exposure classified on the three basis were: 1) Personal exposure 2) Occupational exposure 3) Community exposure

CAUSES OF AIR POLLUTION Population Industrial development Radio-active materials Natural causes Volcano Eruptions Increase in transport facilities Household and Farming Chemicals Deforestation Fossil-Fuel Emissions (while mining)

Scales of air pollution • The air pollution problem may occur in three scales: • MICRO SCALES: Few meters (e.g. House) • MESO SCALES: Few Hectares (e.g. City/ State) • MACRO SCALES: Regional or continental scale (e.g. Country)

SOURCES OF AIR POLLUTANTS The sources of air pollution can be classified as: 1. Natural sources: * (NO2) from electrical storms * HF and HCL from volcanoes * Air borne particles from soil 2. Manmade sources: * Burning of fossil fuels * Deforestation of forest * Industrial activities

CLASSIFICATION OF AIR POLLUTANTS • According to origin: 1. Primary pollutants: The pollutants that are emitted directly from identifiable sources produced from natural events. (e.g. dust storms and volcanic eruptions) 2. Secondary pollutants: The pollutants that that are formed in the atmosphere by chemical interactions between primary pollutantsand atmospheric constituents. (e.g. Ozone, Sulphuric acid- by the reaction of sulphur dioxide and water; Nitric acid – by the reaction of NO2 and water.)

CLASSIFICATION OF AIR POLLUTANTS • According to the state of matter: 1. Gaseous air pollutants: These pollutants are in gaseous state in normal pressure and temperature.(e.g. NO2, SO2 ,CO2) 2. Particulate air pollutants: These are suspended droplets, solid particles, or the mixture of both gases and solids. • According to the sources: 1. Natural sources 2.Manmade sources

NOTE: Some of the important air pollutants include: • Smoke , fog , smog • Oxides of sulphur & nitrogen • Fumes, mists, aerosols • Carbon monoxide (CO) • Volatile Organic Compounds (VOC’s) • Lead • SPM, TSPM (Total Suspended Particulate Matter) • Hydrocarbons & organic compounds • Haze, smaze

Some environmental poisons can cause acute illness and even death or chronic diseases which may take some years to appear. • Air pollution mainly affect the respiratory system leading to diseases like bronchitis, emphysema, asthma and lung cancer. • Lung cancer is caused mainly due to the polluted air containing carcinogens. • SO2 is the most serious and wide spread air pollutant causing cough, shortness of breath, accute irritation to the membrane of the eyes and also affecting the larynx (voice box). • CO often affects the oxygen carrying capacity of blood. • NO3 is reported to be a pulmonary irritant and its tumor concentration may cause pulmonary haemorrhage. EFFECT ON HUMAN HEALTH

NOTE: • Smog has a killer effect, which is also the result of air pollution. In December 1952, about 4,000 peoples were dead in London due to smog: Similarly; in 1956, 1957 & 1962 between 700 to 1000 were dead. • H2S & also a toxic lead (Pb) produced from the automobile exhausts is a cumulative poison and it is very hazardous to children and may even cause brain damage.

Fluorine is the most toxic pollutant for plants which is taken by them, from the air inhaled is contaminated with fluorine; produced by the manufacturing process of aluminum, glass, phosphate fertilizers and clay baking operations. Its effects on plants include: • Photo-toxicological effect is obtained , when then intake concentration of fluorine exceeds about 0.3 µg/m3 • Yield and photosynthesis of crops were reduced. • Quantities and nutrientspresent in the plants were reduced. EFFECT ON Vegetation

The animals which consumes the polluted plants were highly affected. The important pollutants that affect the animals were: • Fluorine: Its effects are harmful which includes lack of appetite, general illness, reduction in growth, fertility and milk production. • Arsenic: It creates Arsenic poisoning on animals with effective symptoms of thirst, vomiting, discomfort, irregular pulse and respiration. • Lead: It creates Lead poisoning by the lead emitted from coal based industries (coke ovens) causing harmful effects like prostration, paralysis of digestive tract, diarrhoea, staggering, inability to stand. EFFECT ON animals

NOTE:- • EFFECT ON Aquatic life: Atmospheric gas pollutants such as CO, CO2, sulphur oxides (like SO2) and nitrogen oxides (Nox) react with rain and forms acidic rain (called acid rain,H2SO4,H2CO3,HNO3) affects fresh water bodies and aquatic life (especially fishes) in the water resources.

Air pollution affect various materials and services in the following ways: • Corrosion • Chemical attack (direct and indirect) • Abrasion • Deposition and removal In the urban areas, air pollution causes severe economic losses by wastage of materials. The atmospheric deterioration of materials is caused due to moisture, temperature, sunlight and air movement. Effect on property

Air pollutants cause non-repairabledamages to the art treasures of a country. TheTaj Mahal inIndia, The Colosseum in Rome,The San Marco Basilica inVenice have shown signs of decay and corrosion attacks due to the severe effects of air pollution. • It can degrade scenic landscapes, and in extreme cases, completely obscure them. Particulate matter suspended in the air is the main cause of visibility degradation which is an environmental quality that is valued for aesthetic reasons that are difficult to express or quantify. EFFECT ON aesthetic values

Visibility depends on the transmission of light through the atmosphere and the capacity of eye to differentiate the object. It can be reduced due to the pollutants in air depends on the following factors: • Size, concentrationand physical characteristics of particulate matter. • Nature of particulate matter in ambient air. • Volume of air into which it gets mixed up. GLOBAL ENVIRONMENTAL ISSUES: • Acid rain • Ozone Depletion (Ozone hole) • Global Warming EFFECT ON visibility

AMBIENT AIR QUALITY STANDARDS • Ambient air quality refers to the condition or quality of air surrounding us in the outdoors. National Ambient Air Quality Standards are the standards for ambient air quality set by the Central Pollution Control Board (CPCB) that is applicable nationwide. The CPCB has been conferred this power by the Air (Prevention and Control of Pollution) Act, 1981. • It is important for any numerical standard that averaging period, unit, and statistical measure of pollutant released to an atmosphere. The criteria are specified for a variety of reasons including for the protection of human health, buildings, crops, vegetation, ecosystems, and for planning.

AMBIENT AIR QUALITY • All of the Central and State Pollution Control Boards are functioning under the control of the Ministry of Environment and Forest. • Annual Time Weighed Average (ATA) is the arithmetic mean of minimum site taken twice a week 24 hours at uniform intervals. • Other Air Quality Standards: * Point of Impingement Standards * Soiling Index * Odour Standards

AIR QUALITY INDEX • AQI or Pollution Standards Index (PSI), is a uniform system developed by EPA (Environmental Protection Agency) of USA; to enable the public to determine whether the air quality levels in particular location. • The most important number on this scale is 100, since the number corresponds to the National Ambient Air Quality Standard established under the Clean Air Act, 1970.

AQI MEASURES • When the AQI level is excess of 100, then the pollutant is higher and leading to a unhealthy range on a given day. • When the AQI level equals or lesser than 100, then the pollutant reading is in the satisfactory range on a particular day. • The AQI of EPA is mainly based on the 5 major air pollutants.

NOTE: The AQI measures five criteria of air pollutants such as: • Particulate mater • Sulphur dioxide (SO2) • Carbon Monoxide (CO) • Nitrogen dioxide (NO2) • Ozone (O3) And it converts the measured pollutant concentration in a community’s air to a number on a scale of 0 to 500.

Emission standards • Emission standards are the legalrequirements governing air pollutants released into the atmosphere. • They are generally designed to achieve air quality standards to protect the human life. • Emission standards set quantitative limits on the permissible amount of specific air pollutants that may be released from specific sources over specific timeframes.

Emission standards • Emission intensity (Carbon intensity) is the emission rate of the given pollutant relative to the intensity of the specific activity, or an industrial production process. • Emission standards are mainly implemented based on the following two types of sources production: 1. Emission standards for mobile sources 2.Emission standards for stationary sources

Bharat stage emission standards • Bharat stage emission standards (BSES) are emission standards instituted by the Government of India to regulate the output of air pollutants from CI engines andSI engines of vehicles. The standards and the timeline for implementation are set by the Central Pollution Control Boardunder the Ministry of Environment, Forest and Climate Change. • These standards were first introduced in 2000 based on the European regulations.

Bharat stage emission standards Emission standards in India have been adopted for new engines or vehicles on the following categories: • Cars and Light Trucks –Emissions • Cars and Light Trucks – Fuel Economy • 2- and 3- Wheel Vehicles • Heavy-Duty Truck and Bus engines • Non-Road (Off-Road) Diesel Engines • Generator Sets

TYPES OF EMISSIONS Evaporative Emissions. Gasoline, antifreeze, and other auto liquids are made up of hydrocarbons that can be released into the air in many different ways. Refuelling Losses Exhaust Emissions Perfect Combustion Typical Combustion Carbon Dioxide (CO) Nitrogen Oxides (NOx) Carbon Monoxide (CO)

EMISSION STANDARDS IN INDIA

Air Pollution and Control Engineering