Unit 2

Effects of air pollution

Air pollution• Air pollution is a major environmental health problem affecting the

developing and the developed countries alike. • The effects of air pollution on health are very complex as there are many

different sources and their individual effects vary from one to the other. • It is not only the ambient air quality in the cities but also the indoor air

quality in the rural and the urban areas that are causing concern.• In fact in the developing world the highest air pollution exposures occur

in the indoor environment. • Air pollutants that are inhaled have serious impact on human

health affecting the lungs and the respiratory system; they are also taken up by the blood and pumped all round the body.

• These pollutants are also deposited on soil, plants, and in the water, further contributing to human exposure.

Impact of air pollution on health

• Indoor air pollution can be particularly hazardous to health as it is released in close proximity to people.

• It is stated that a pollutant released indoors is many times more likely to reach the lung than that released outdoors.

• In the developing countries a fairly large portion of the population is dependent on biomass for their energy requirements.

• These include wood, charcoal, agricultural residue, and animal waste. Open fires used for cooking and heating are commonly found in the household both in the rural and the urban areas.

• The stove is often at floor level, adding to the risk of accident and the hygiene factor.• In addition, they are often not fitted with a chimney to remove the pollutants. In such households the

children and women are most likely to be affected, as they are the group that spends more time indoors.

• The main pollutant in this environment is the SPM. • In fact, death due to indoor air pollution, mainly particulate matters, in the rural areas of India are one

of the highest in the world. • Many of the deaths are due to acute respiratory infections in children; others are due to

cardiovascular diseases, lung cancer, and chronic respiratory diseases in adults. • If emissions are high and ventilation is poor, household use of coal and biomass can severely affect the

indoor air quality.

Health impact of specific air pollutants

• Tobacco smoke. Tobacco smoke generates a wide range of harmful chemicals and is a major cause of ill health, as it is known to cause cancer, not only to the smoker but affecting passive smokers too. It is well-known that smoking affects the passive smoker ranging from burning sensation in the eyes or nose, and throat irritation, to cancer, bronchitis, severe asthma, and a decrease in lung function.

• Biological pollutants. These are mostly allergens that can cause asthma, hay fever, and other allergic diseases.

• Volatile organic compounds. Volatile compounds can cause irritation of the eye, nose and throat. In severe cases there may be headaches, nausea, and loss of coordination. In the longer run, some of them are suspected to cause damage to the liver and other parts of the body.

• Formaldehyde. Exposure causes irritation to the eyes, nose and may cause allergies in some people.

• Radon. A radioactive gas that can accumulate inside the house, it originates from the rocks and soil under the house and its level is dominated by the outdoor air and also to some extent the other gases being emitted indoors. Exposure to this gas increases the risk of lung cancer.

• Ozone. Exposure to this gas makes our eyes itch, burn, and water and it has also been associated with increase in respiratory disorders such as asthma. It lowers our resistance to colds and pneumonia.

• Oxides of nitrogen. This gas can make children susceptible to respiratory diseases in the winters.

• Carbon monoxide. CO (carbon monoxide) combines with haemoglobin to lessen the amount of oxygen that enters our blood through our lungs. The binding with other proteins causes changes in the function of the affected organs such as the brain and the cardiovascular system, and also the developing foetus. It can impair our concentration, slow our reflexes, and make us confused and sleepy.

• Sulphur dioxide. SO2 (sulphur dioxide) in the air is caused due to the rise in combustion of fossil fuels. It can oxidize and form sulphuric acid mist. SO2 in the air leads to diseases of the lung and other lung disorders such as wheezing and shortness of breath. Long-term effects are more difficult to ascertain as SO2 exposure is often combined with that of SPM.

SPM (suspended particulate matter).

• Suspended matter consists of dust, fumes, mist and smoke. • The main chemical component of SPM that is of major concern

is lead, others being nickel, arsenic, and those present in diesel exhaust.

• These particles when breathed in, lodge in our lung tissues and cause lung damage and respiratory problems.

• The importance of SPM as a major pollutant needs special emphasis as a) it affects more people globally than any other pollutant on a continuing basis; b) there is more monitoring data available on this than any other pollutant; and c) more epidemiological evidence has been collected on the exposure to this than to any other pollutant.

Contd..• The emission of toxic pollutants into the air can have serious effects to

human health and the environment. • Human exposure to these pollutants can include both short-term

(acute) and long-term (chronic) complications. • Many factors can affect how different toxic air pollutants may impact

human health, including the quantity which a person is exposed to, the development stage of the person, the duration and frequency of the exposure, the toxicity level of the pollutant, and the person's overall health and level of resistance or susceptibility.

• Short-term exposures can include effects such as eye irritation, nausea or difficulty in breathing.

• Long-term exposures to many air toxics may result in damage to the respiratory or nervous systems, birth defects, and reproductive effects.

Contd…• In addition, toxic air pollutants can have indirect effects on human

health through deposition onto soil or into lakes and streams, potentially affecting ecological systems and eventually human health through consumption of contaminated food.

• Exposure to air pollution is associated with numerous effects on human health, including pulmonary, cardiac, vascular, and neurological impairments.

• The health effects vary greatly from person to person. • High-risk groups such as the elderly, infants, pregnant women, and

sufferers from chronic heart and lung diseases are more susceptible to air pollution.

• Children are at greater risk because they are generally more active outdoors and their lungs are still developing.

• Although in humans pollutants can affect the skin, eyes and other body systems, they affect primarily the respiratory system.

• Air is breathed in through the nose, which acts as the primary filtering system of the body. • The small hairs and the warm, humid conditions in the nose effectively remove the larger

pollutant particles. • The air then passes through the pharynx, esophagus, and larynx before reaching the top of the

trachea. • The trachea divides into two parts, the left and the right bronchi. • Each bronchi subdivides into increasingly smaller compartments. The smallest compartments of

the bronchi are called bronchioles, which contain millions of air sacs called alveoli. • Together, the bronchioles and alveoli make up the lungs.• Both gaseous and particulate air pollutants can have negative effects on the lungs.

• Solid particles can settle on the walls of the trachea, bronchi, and bronchioles.• Most of these particles are removed from the lungs through the cleansing (sweeping) action of

"cilia", small hairlike outgrowths of cells, located on the walls of the lungs. This is what occurs when you cough or sneeze.

Pollution transport

• A cough or sneeze transports the particles to the mouth. • The particles are removed subsequently from the body

when they are swallowed or expelled. • However, extremely small particles may reach the alveoli,

where it takes weeks, months, or even years for the body to remove the particles.

• Gaseous air pollutants may also affect the function of the lungs by slowing the action of the cilia.

• Continuous breathing of polluted air can slow the normal cleansing action of the lungs and result in more particles reaching the lower portions of the lung.

Table 1: Sources, Health and Welfare Effects for Criteria Pollutants.

Pollutant Description Sources Health Effects Welfare EffectsCarbon Monoxide (CO)

Colorless, odorless gas

Motor vehicle exhaust, indoor sources include kerosene or wood burning stoves.

Headaches, reduced mental alertness, heart attack, cardiovascular diseases, impaired fetal development, death.

Contribute to the formation of smog.

Sulfur Dioxide (SO2) Colorless gas that dissolves in water vapor to form acid, and interact with other gases and particles in the air.

Coal-fired power plants, petroleum refineries, manufacture of sulfuric acid and smelting of ores containing sulfur.

Eye irritation, wheezing, chest tightness, shortness of breath, lung damage.

Contribute to the formation of acid rain, visibility impairment, plant and water damage, aesthetic damage.

Nitrogen Dioxide (NO2)

Reddish brown, highly reactive gas.

Motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels.

Susceptibility to respiratory infections, irritation of the lung and respiratory symptoms (e.g., cough, chest pain, difficulty breathing).

Contribute to the formation of smog, acid rain, water quality deterioration, global warming, and visibility impairment.

Ozone (O3) Gaseous pollutant when it is formed in the troposphere.

Vehicle exhaust and certain other fumes. Formed from other air pollutants in the presence of sunlight.

Eye and throat irritation, coughing, respiratory tract problems, asthma, lung damage.

Plant and ecosystem damage.

Lead (Pb) Metallic element Metal refineries, lead smelters, battery manufacturers, iron and steel producers.

Anemia, high blood pressure, brain and kidney damage, neurological disorders, cancer, lowered IQ.

Affects animals and plants, affects aquatic ecosystems.

Particulate Matter (PM)

Very small particles of soot, dust, or other matter, including tiny droplets of liquids.

Diesel engines, power plants, industries, windblown dust, wood stoves.

Eye irritation, asthma, bronchitis, lung damage, cancer, heavy metal poisoning, cardiovascular effects.

Visibility impairment, atmospheric deposition, aesthetic damage.

Environmental Pollution Effects on Animals

• Acid rain (formed in the air) destroys fish life in lakes and streams

• Excessive ultraviolet radiation coming from the sun through the ozone layer in the upper atmosphere which is eroded by some air pollutants, may cause skin cancer in wildlife

• Ozone in the lower atmosphere may damage lung tissues of animals

• Along with humans, animals ranging from tiny microbes to large mammals are also dependent on oxygen that is derived from the air.

• When contaminated air is inhaled for breathing oxygen, several harmful gases are also inhaled along with it.

• These harmful gases are believed to affect animals in the same manner as they affect humans.

• Experts also suggest that the particulate matter that the animals inhale over a prolonged period can get accumulated in their tissues and damage their organs in the long run.

• Other than inhaling the harmful contaminants directly, animals can also come in contact with these contaminants from the food that they eat and by absorption through their skin.

• More importantly, animals are more vulnerable to this issue as compared to us humans, as they are not well-equipped to protect themselves from it as we are.

• The forage crops are sometimes contained with metallic pollutants, such as, lead, arsenic and molybdenum in mining and thermal power plants area due to air pollution.

• The domestic animals feeding on contaminated fodder suffer from different diseases.

• Air contaminated with ozone causes pulmonary changes, oedema and haemorrhage in dogs, cats, and rabbits.

• Animals feeding on fluoride compound containing fodder may suffer from fluorosis.

• Cattle and sheep are most frequently affected animals.

Environmental Pollution Effects on plants

• Acid rain can kill trees, destroy the leaves of plants, can infiltrate soil by making it unsuitable for purposes of nutrition and habitation

• Ozone holes in the upper atmosphere can allow excessive ultraviolet radiation from the sun to enter the Earth causing damage to trees and plants

• Ozone in the lower atmosphere can prevent plant respiration by blocking stomata (openings in leaves) and negatively affecting plants’ photosynthesis rates which will stunt plant growth; ozone can also decay plant cells directly by entering stomata

• Air pollution has serious harmful effects on plants. • Sulphur dioxide causes chlorosis. • It results in the death of cells and tissues.• Forest trees are worst affected by sulphur dioxide pollutants. • Excessive sulphur dioxides make the cells inactive and finally are killed. • At lower concentrations, brownish red colour of leaf, choruses and necrosis take place• Fluorides damage leafy vegetables such as lettuce and spinach. Oxides of nitrogen and

fluorides reduce crop yields. • Photochemical smog bleaches and blazes foliage of plants. Hydrocarbons cause

premature fall of leaves and flower buds, discolouration of sepals and curling of petals.

• Ozone damages cereals, fruits and cotton crops. It also causes premature yellowing and shedding of leaves.

• Air pollution inhibits growth of lichens on trees. Therefore, lichen can serve as indicator of air pollutions.

Air pollution effects on materials

• The acid rain and photochemical smog affect metals and buildings.

• Acid rain pollutes the soil and water sources. • Acidic products of the air pollutant cause disintegration of

textile, paper. • Many small industrial units and sources of locomotive

pollutants have been sifted to save the famous marble structure, Taj Mahal at Agra.

• Hydrogen sulphide decolorizes silver and lead paints. • Ozone oxidizes rubber goods.

• Sulphur dioxide with water produces sulphurous and sulphuric acids that are extremely corrosive.

• Different metals, such as iron, aluminum and copper are corroded when exposed to contaminated air.

• Building and other materials are disfigured by deposition of soot.

• Increase in carbon dioxide concentration increases the temperature of the earth.

• Depletion of ozone layer due to fluoro carbon of aerosol causes the exposure of U. V. radiation which is lethal.

Industrial smog

• Source: Pollution from the burning of coal and oil that contains sulfur

• Consists mainly of: Sulfur Dioxide, Sulfur Trioxide, soot and ash (particulate matter) and sulfuric acid

• It can cause breathing difficulties in humans, plus acid rain damage to plants, aquatic systems, and metal or stone objects

• London and Chicago have problems with industrial smog.• Methods of reducing this smog: Alkaline Scrubbers

reduce SO2 and SO3 levels; electrostatic precipitators reduce particulates.

Photochemical smog

• Source: Mainly automobile pollution• Contains: Nitrogen Oxides, Ozone, Alkanals, Peroxyacyl

Nitrates (PANs), plus hundreds of other substances• Effects: PANs cause eyes to water and can damage

plants, O3 irritates eyes and deteriorates rubber and plants, NOx causes acid rain.

• First observed in LA in the 1940s, Manila and Mexico City also experience this kind of smog

• Catalytic Converters change NO to N2, Lean burning engines reduce Nox, but create more CO and Hydrocarbons.

Thermal inversions• Abnormal arrangement of air masses• Abnormal arrangement of air masses

– Abnormal arrangement of air masses– A warmer layer of air is trapped between two layers of colder air– This causes pollutants to be trapped near the earth’s surface– Can form when hills or mountains stop horizontal winds, causing pollutants to collect over a city.– Warm air collects over the polluted air, acting as a lid to stop the pollutants from being dispersed.– In London, 1952, a thermal inversion lasting several days resulted in the deaths of several

thousand people, most severely affecting the very old and young– Thermal inversions worsen any type of smog– A warmer layer of air is trapped between two layers of colder air

• Can form when hills or mountains stop hizontal winds, causing pollutants to collect over a city.• Warm air collects over the polluted air, Abnormal arrangement of air masses

– A warmer layer of air is trapped between two layers of colder air– This causes pollutants to be trapped near the earth’s surface

• Can form when hills or mountains stop horizontal winds, causing pollutants to collect over a city.• Warm air collects over the polluted air, acting as a lid to stop the pollutants from being dispersed.• In London, 1952, a thermal inversion lasting several days resulted in the deaths of several thousand people, most severely affecting the very old and young• Thermal inversions worsen any type of smog• acting as a lid to stop the pollutants from being dispersed.• In London, 1952, a thermal inversion lasting several days resulted in the deaths of several thousand people, most severely affecting the very old and young• Thermal inversions worsen any type of smog

– A warmer layer of air is trapped between two layers of colder air– This causes pollutants to be trapped near the earth’s surface

• Can form when hills or mountains stop horizontal winds, causing pollutants to collect over a city.• Warm air collects over the polluted air, acting as a lid to stop the pollutants from being dispersed.• In London, 1952, a thermal inversion lasting several days resulted in the deaths of several thousand people, most severely affecting the very old and young• Thermal inversions worsen any type of smog• Abnormal arrangement of air masses

– A warmer layer of air is trapped between two layers of colder air– This causes pollutants to be trapped near the earth’s surface

• Can form when hills or mountains stop horizontal winds, causing pollutants to collect over a city.• Warm air collects over the polluted air, acting as a lid to stop the pollutants from being dispersed.• In London, 1952, a thermal inversion lasting several days resulted in the deaths of several thousand people, most severely affecting the very old and young• Thermal inversions worsen any type of smog

Thermal Inversions

Normal Conditions

Cooler Air

Winds disperse pollutants worldwide

Warmer Air

Pollutants dissociate upwards

Thermal Inversion

Cooler Air

Warm air layer

Cool Air trapped at surface

Pollutants trapped at surface

London Smog

• London, England– Most of the smog

damage occurred in East London

Causes

• The smoke from the factories

• Vehicles • Pollution• Noxious fumes

Death Tolls

• 4,703 people died during the two weeks of the London Smog

• Death rate peaked on the 8th and 9th days at 900 deaths per day

Health Effects

• Pneumonia• Bronchitis• Tuberculosis• Heart Failure• Asthma• Respiratory and

Cardiac Distress

Pictures

• People helping the trolleys along the road through the London Smog.

Cleaning the Smog

• 1956 Clean Air Act– This act authorized local councils to set up smokeless

zones and give grants to householders to convert their homes from traditional coal fires to heaters fuelled by gas, oil, smokeless coal or electricity.

• 1968 Clean Air Act; Tall Chimneys – This act brought in the basic principal for the use of tall

chimneys for industries burning coal, liquid or gaseous fuels.

Los Angeles smog

• This mixture of O3, NO2 and VOCs is called “photochemical smog” or to distinguish it from “sulfurous smog” or “London smog

Ranking

• The following chart shows the ranking of the 5 major air pollutants monitored by the EPA.

• The chart shows the quantity of pollutant as a percentage to the minimum allowed by the EPA.

• It is interesting to note that in the majority of cases Ozone is the major pollutant facing most cities

Solving the smog problem

• The first step is to limit auto exhaust• This is an ongoing process – the EPA regularly

tightens the emissions requirements (catalytic converters)

• But this only applies to new cars: older vehicles are grandfathered in under the previous emissions standards

Bhopal gas tragedy• The Bhopal disaster, also referred to as the Bhopal gas tragedy, was a gas

leak incident in India, considered one of the world's worst industrial disasters.

• It occurred on the night of 2–3 December 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Prades India.

• A leak of methyl isocyanate gas and other chemicals from the plant resulted in the exposure of hundreds of thousands of people.

• The toxic substance made its way in and around the shanty towns located near the plant.

• Estimates vary on the death toll. The official immediate death toll was 2,259 and the government of Madhya Pradesh has confirmed a total of 3,787 deaths related to the gas release.

• Others estimate 8,000 died within two weeks and another 8,000 or more have since died from gas-related diseases.

• A government affidavit in 2006 stated the leak caused 558,125 injuries including 38,478 temporary partial and approximately 3,900 severely and permanently disabling injuries.

During the night of 2–3 December 1984, water entered Tank E610 containing 42 tons of MIC. The resulting exothermic reaction increased the temperature inside the tank to over 200 °C (392 °F) and raised the pressure. About 30 metric tons of methyl isocyanate (MIC) escaped from the tank into the atmosphere in 45 to 60 minutes. The gases were blown in southeastern direction over Bhopal. Theories differ as to how the water entered the tank. At the time, workers were cleaning out a clogged pipe with water about 400 feet from the tank. The operators assumed that owing to bad maintenance and leaking valves, it was possible for the water to leak into the tank. However, this water entry route could not be reproduced. UCL also maintains that this route was not possible, but instead alleges water was introduced directly into the tank as an act of sabotage by a disgruntled worker via a connection to a missing pressure gauge on the top of the tank

• Early the next morning, a UCIL manager asked the instrument engineer to replace the gauge.

• UCIL's investigation team found no evidence of the necessary connection; however, the investigation was totally controlled by the government, denying UCC investigators access to the tank or interviews with the operators.

• The 1985 reports give a picture of what led to the disaster and how it developed, although they differ in details.

• Factors leading to the magnitude of the gas leak include:– Storing MIC in large tanks and filling beyond recommended levels– Poor maintenance after the plant ceased MIC production at the end of

1984– Failure of several safety systems (due to poor maintenance)– Safety systems being switched off to save money— including the MIC tank

refrigeration system which could have mitigated the disaster severity– The problem was made worse by the mushrooming of slums in the vicinity

of the plant, non-existent catastrophe plans, and shortcomings in health care and socio-economic rehabilitation.

Short term health effects

• The leakage caused many short term health effects in the surrounding areas. Apart from MIC, the gas cloud may have contained phosgene, hydrogen cyanide, carbon monoxide, hydrogen chloride, oxides of nitrogen, monomethyl amine (MMA) and carbon dioxide either produced in the storage tank or in the atmosphere.

• The gas cloud was composed mainly of materials denser than the surrounding air, stayed close to the ground and spread outwards through the surrounding community.

• The initial effects of exposure were coughing, vomiting, severe eye irritation and a feeling of suffocation.

• People awakened by these symptoms fled away from the plant. • Those who ran inhaled more than those who had a vehicle to ride. Owing to their

height, children and other people of shorter stature inhaled higher concentrations. Many people were trampled trying to escape.

• Thousands of people had succumbed by the morning hours. • There were mass funerals and mass cremations. Bodies were dumped into the Narmada

River, less than 100 km from Bhopal. 170,000 people were treated at hospitals and temporary dispensaries. 2,000 buffalo, goats, and other animals were collected and buried.

• Within a few days, leaves on trees yellowed and fell off. Supplies, including food, became scarce owing to suppliers' safety fears. Fishing was prohibited causing further supply shortages.

• A total of 36 wards were marked by the authorities as being "gas affected", affecting a population of 520,000. Of these, 200,000 were below 15 years of age, and 3,000 were pregnant women.

• In 1991, 3,928 deaths had been certified. Independent organizations recorded 8,000 deaths in the first few days. Other estimations vary between 10,000 and 30,000. Another 100,000 to 200,000 people are estimated to have permanent injuries of different degrees.

• The acute symptoms were burning in the respiratory tract and eyes, blepharospasm, breathlessness, stomach pains and vomiting.

• The causes of deaths were choking, reflexogenic circulatory collapse and pulmonary oedema.• Findings during autopsiesrevealed changes not only in the lungs but also cerebral

oedema, tubular necrosis of the kidneys, fatty degeneration of the liver and necrotising enteritis.

• The stillbirth rate increased by up to 300% and neonatal mortality rate by around 200%.