`color{green}(★)` Tropospheric pollution occurs due to the presence of undesirable solid or gaseous particles in the air.
`color{green}(★)` The following are the major gaseous and particulate pollutants present in the troposphere:
1. Gaseous air pollutants: These are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.
2. Particulate pollutants: These are dust, mist, fumes, smoke, smog etc.
`color{green}("𝟏. 𝐆𝐚𝐬𝐞𝐨𝐮𝐬 𝐚𝐢𝐫 𝐩𝐨𝐥𝐥𝐮𝐭𝐚𝐧𝐭𝐬")`
`color{red}(" (𝐚) 𝐎𝐱𝐢𝐝𝐞𝐬 𝐨𝐟 𝐒𝐮𝐥𝐩𝐡𝐮𝐫:")`
`color{green}(★)` Oxides of sulphur are produced when sulphur containing fossil fuel is burnt. It has been reported that even a low concentration of sulphur dioxide causes respiratory diseases e.g., asthma, bronchitis, emphysema in human beings.
`color{green}(★)` The most common species, sulphur dioxide, is a gas that is poisonous to both animals and plants. Sulphur dioxide causes irritation to the eyes, resulting in tears and redness. High concentration of `color{red}(SO_2)` leads to stiffness of flower buds which eventually fall off from plants.
`color{green}(★)` Uncatalysed oxidation of sulphur dioxide is slow. However, the presence of particulate matter in polluted air catalyses the oxidation of sulphur dioxide to sulphur trioxide.
`color{red}(2SO_2 (g) +O_2 (g) → 2SO_3(g))`
The reaction can also be promoted by ozone and hydrogen peroxide.
`color{red}(SO_2 (g) +O_3 (g) → SO_3(g) + O_2 (g))`
`color{red}( SO_2(g) + H_2O_2(l) → H_2SO_4(aq))`
`color{green}(★)` `color{red}("(𝐛) 𝐎𝐱𝐢𝐝𝐞𝐬 𝐨𝐟 𝐍𝐢𝐭𝐫𝐨𝐠𝐞𝐧:")`
`color{green}(★)` Dinitrogen and dioxygen are the main constituents of air.
`color{green}(★)` At high altitudes when lightning strikes, they combine to form oxides of nitrogen.
`color{green}(★)` `color{red}(NO_2)` is oxidised to nitrate ion, `color{red}(NO_3^( −))` which is washed into soil, where it serves as a fertilizer.
`color{green}(★)` In an automobile engine, (at high temperature) when fossil fuel is burnt, dinitrogen and dioxygen combine to yield significant quantities of nitric oxide `color{red}((NO))` and nitrogen dioxide `color{red}(( NO_2 ))` as given below:
`color{red}(N_2 (g) + O_2 (g) overset(1483K)→ 2NO(g))`
`color{green}(★)` `color{red}(NO)` reacts instantly with oxygen to give `color{red}(NO_2)`
`color{red}(2NO (g) + O_2 (g) → 2NO_2 (g))`
`color{green}(★)` Rate of production of `color{red}(NO_2)` is faster when nitric oxide reacts with ozone in the stratosphere.
`color{red}(NO (g) + O_3 (g) → NO_2 (g) + O_2 (g))`
`color{green}("★ 𝐄𝐅𝐅𝐄𝐂𝐓𝐒 𝐎𝐅 𝐎𝐗𝐈𝐃𝐄𝐒 𝐎𝐅 𝐍𝐈𝐓𝐑𝐎𝐆𝐄𝐍:")`
`color{green}(★)` The irritant red haze in the traffic and congested places is due to oxides of nitrogen.
`color{green}(★)` Higher concentrations of `color{red}(NO_2)` damage the leaves of plants and retard the rate of photosynthesis.
`color{green}(★)` Nitrogen dioxide is a lung irritant that can lead to an acute respiratory disease in children.
`color{green}(★)` It is toxic to living tissues also.
`color{green}(★)` Nitrogen dioxide is also harmful to various textile fibres and metals.
`color{red}("(c) 𝐇𝐲𝐝𝐫𝐨𝐜𝐚𝐫𝐛𝐨𝐧𝐬:")` Hydrocarbons are composed of hydrogen and carbon only and are formed by incomplete combustion of fuel used in automobiles.
`color{green}(" ★ 𝐇𝐀𝐑𝐌𝐅𝐔𝐋 𝐄𝐅𝐅𝐄𝐂𝐓𝐒 𝐎𝐅 𝐇𝐘𝐃𝐑𝐎𝐂𝐀𝐑𝐁𝐎𝐍𝐒:")`
`color{green}(★)` Hydrocarbons are carcinogenic, i.e., they cause cancer.
`color{green}(★)` They harm plants by causing ageing, breakdown of tissues and shedding of leaves, flowers and twigs.
`color{green}("(𝐝) 𝐎𝐱𝐢𝐝𝐞𝐬 𝐨𝐟 𝐂𝐚𝐫𝐛𝐨𝐧")`
`color{red}("(𝐢 ) 𝐂𝐚𝐫𝐛𝐨𝐧 𝐦𝐨𝐧𝐨𝐱𝐢𝐝𝐞:")`
`color{green}(★)` Carbon monoxide `color{red}((CO))` is one of the most serious air pollutants. It is produced as a result of incomplete combustion of carbon
`color{green}(★)` It is a colourless and odourless gas, highly poisonous to living beings because of its ability to block the delivery of oxygen to the organs and tissues.
`color{green}(★)` Carbon monoxide is mainly released into the air by automobile exhaust. Other sources, which produce `color{red}(CO)`, involve incomplete combustion of coal, firewood, petrol, etc.
`color{brown}(" ★ 𝐉𝐔𝐒𝐓 𝐅𝐎𝐑 𝐂𝐔𝐑𝐈𝐎𝐔𝐒")`
`color{green}(★)` `color{green}("𝐃𝐨 𝐲𝐨𝐮 𝐤𝐧𝐨𝐰 𝐰𝐡𝐲 𝐜𝐚𝐫𝐛𝐨𝐧 𝐦𝐨𝐧𝐨𝐱𝐢𝐝𝐞 𝐢𝐬 𝐩𝐨𝐢𝐬𝐨𝐧𝐨𝐮𝐬?")`
`color{green}(★)` It binds to haemoglobin to form carboxyhaemoglobin, which is about 300 times more stable than the oxygen-haemoglobin complex. In blood, when the concentration of carboxyhaemoglobin reaches about `3–4 %` the oxygen carrying capacity of blood is greatly reduced. This oxygen deficiency, results into headache, weak eyesight, nervousness and cardiovascular disorder. This is the reason why people are advised not to smoke. In pregnant women who have the habit of smoking the increased `color{red}(CO)` level in blood may induce premature birth, spontaneous abortions and deformed babies.
`color{red}("(𝐢𝐢) 𝐂𝐚𝐫𝐛𝐨𝐧 𝐝𝐢𝐨𝐱𝐢𝐝𝐞:")`
`color{green}(★)` `color{green}("𝐒𝐎𝐔𝐑𝐂𝐄𝐒 𝐎𝐅 𝐂𝐀𝐑𝐁𝐎𝐍 𝐃𝐈𝐎𝐗𝐈𝐃𝐄:")` Carbon dioxide `color{red}((CO_2))` is released into the atmosphere by respiration, burning of fossil fuels for energy, and by decomposition of limestone during the manufacture of cement. It is also emitted during volcanic eruptions.
`color{green}(★)` Carbon dioxide gas is confined to troposphere only. Normally it forms about 0.03 % by volume of the atmosphere.
`color{green}(★)` Excess of `color{red}(CO_2)` in the air is removed by green plants and this maintains an appropriate level of `color{red}(CO_2) ` in the atmosphere. Green plants require `color{red}(CO_2)` for photosynthesis and they, in turn, emit oxygen, thus maintaining the delicate balance.
`color{green}(★)` The increased amount of `color{red}(CO_2)` in the air is mainly responsible for global warming.
`color{green}(★)` Tropospheric pollution occurs due to the presence of undesirable solid or gaseous particles in the air.
`color{green}(★)` The following are the major gaseous and particulate pollutants present in the troposphere:
1. Gaseous air pollutants: These are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.
2. Particulate pollutants: These are dust, mist, fumes, smoke, smog etc.
`color{green}("𝟏. 𝐆𝐚𝐬𝐞𝐨𝐮𝐬 𝐚𝐢𝐫 𝐩𝐨𝐥𝐥𝐮𝐭𝐚𝐧𝐭𝐬")`
`color{red}(" (𝐚) 𝐎𝐱𝐢𝐝𝐞𝐬 𝐨𝐟 𝐒𝐮𝐥𝐩𝐡𝐮𝐫:")`
`color{green}(★)` Oxides of sulphur are produced when sulphur containing fossil fuel is burnt. It has been reported that even a low concentration of sulphur dioxide causes respiratory diseases e.g., asthma, bronchitis, emphysema in human beings.
`color{green}(★)` The most common species, sulphur dioxide, is a gas that is poisonous to both animals and plants. Sulphur dioxide causes irritation to the eyes, resulting in tears and redness. High concentration of `color{red}(SO_2)` leads to stiffness of flower buds which eventually fall off from plants.
`color{green}(★)` Uncatalysed oxidation of sulphur dioxide is slow. However, the presence of particulate matter in polluted air catalyses the oxidation of sulphur dioxide to sulphur trioxide.
`color{red}(2SO_2 (g) +O_2 (g) → 2SO_3(g))`
The reaction can also be promoted by ozone and hydrogen peroxide.
`color{red}(SO_2 (g) +O_3 (g) → SO_3(g) + O_2 (g))`
`color{red}( SO_2(g) + H_2O_2(l) → H_2SO_4(aq))`
`color{green}(★)` `color{red}("(𝐛) 𝐎𝐱𝐢𝐝𝐞𝐬 𝐨𝐟 𝐍𝐢𝐭𝐫𝐨𝐠𝐞𝐧:")`
`color{green}(★)` Dinitrogen and dioxygen are the main constituents of air.
`color{green}(★)` At high altitudes when lightning strikes, they combine to form oxides of nitrogen.
`color{green}(★)` `color{red}(NO_2)` is oxidised to nitrate ion, `color{red}(NO_3^( −))` which is washed into soil, where it serves as a fertilizer.
`color{green}(★)` In an automobile engine, (at high temperature) when fossil fuel is burnt, dinitrogen and dioxygen combine to yield significant quantities of nitric oxide `color{red}((NO))` and nitrogen dioxide `color{red}(( NO_2 ))` as given below:
`color{red}(N_2 (g) + O_2 (g) overset(1483K)→ 2NO(g))`
`color{green}(★)` `color{red}(NO)` reacts instantly with oxygen to give `color{red}(NO_2)`
`color{red}(2NO (g) + O_2 (g) → 2NO_2 (g))`
`color{green}(★)` Rate of production of `color{red}(NO_2)` is faster when nitric oxide reacts with ozone in the stratosphere.
`color{red}(NO (g) + O_3 (g) → NO_2 (g) + O_2 (g))`
`color{green}("★ 𝐄𝐅𝐅𝐄𝐂𝐓𝐒 𝐎𝐅 𝐎𝐗𝐈𝐃𝐄𝐒 𝐎𝐅 𝐍𝐈𝐓𝐑𝐎𝐆𝐄𝐍:")`
`color{green}(★)` The irritant red haze in the traffic and congested places is due to oxides of nitrogen.
`color{green}(★)` Higher concentrations of `color{red}(NO_2)` damage the leaves of plants and retard the rate of photosynthesis.
`color{green}(★)` Nitrogen dioxide is a lung irritant that can lead to an acute respiratory disease in children.
`color{green}(★)` It is toxic to living tissues also.
`color{green}(★)` Nitrogen dioxide is also harmful to various textile fibres and metals.
`color{red}("(c) 𝐇𝐲𝐝𝐫𝐨𝐜𝐚𝐫𝐛𝐨𝐧𝐬:")` Hydrocarbons are composed of hydrogen and carbon only and are formed by incomplete combustion of fuel used in automobiles.
`color{green}(" ★ 𝐇𝐀𝐑𝐌𝐅𝐔𝐋 𝐄𝐅𝐅𝐄𝐂𝐓𝐒 𝐎𝐅 𝐇𝐘𝐃𝐑𝐎𝐂𝐀𝐑𝐁𝐎𝐍𝐒:")`
`color{green}(★)` Hydrocarbons are carcinogenic, i.e., they cause cancer.
`color{green}(★)` They harm plants by causing ageing, breakdown of tissues and shedding of leaves, flowers and twigs.
`color{green}("(𝐝) 𝐎𝐱𝐢𝐝𝐞𝐬 𝐨𝐟 𝐂𝐚𝐫𝐛𝐨𝐧")`
`color{red}("(𝐢 ) 𝐂𝐚𝐫𝐛𝐨𝐧 𝐦𝐨𝐧𝐨𝐱𝐢𝐝𝐞:")`
`color{green}(★)` Carbon monoxide `color{red}((CO))` is one of the most serious air pollutants. It is produced as a result of incomplete combustion of carbon
`color{green}(★)` It is a colourless and odourless gas, highly poisonous to living beings because of its ability to block the delivery of oxygen to the organs and tissues.
`color{green}(★)` Carbon monoxide is mainly released into the air by automobile exhaust. Other sources, which produce `color{red}(CO)`, involve incomplete combustion of coal, firewood, petrol, etc.
`color{brown}(" ★ 𝐉𝐔𝐒𝐓 𝐅𝐎𝐑 𝐂𝐔𝐑𝐈𝐎𝐔𝐒")`
`color{green}(★)` `color{green}("𝐃𝐨 𝐲𝐨𝐮 𝐤𝐧𝐨𝐰 𝐰𝐡𝐲 𝐜𝐚𝐫𝐛𝐨𝐧 𝐦𝐨𝐧𝐨𝐱𝐢𝐝𝐞 𝐢𝐬 𝐩𝐨𝐢𝐬𝐨𝐧𝐨𝐮𝐬?")`
`color{green}(★)` It binds to haemoglobin to form carboxyhaemoglobin, which is about 300 times more stable than the oxygen-haemoglobin complex. In blood, when the concentration of carboxyhaemoglobin reaches about `3–4 %` the oxygen carrying capacity of blood is greatly reduced. This oxygen deficiency, results into headache, weak eyesight, nervousness and cardiovascular disorder. This is the reason why people are advised not to smoke. In pregnant women who have the habit of smoking the increased `color{red}(CO)` level in blood may induce premature birth, spontaneous abortions and deformed babies.
`color{red}("(𝐢𝐢) 𝐂𝐚𝐫𝐛𝐨𝐧 𝐝𝐢𝐨𝐱𝐢𝐝𝐞:")`
`color{green}(★)` `color{green}("𝐒𝐎𝐔𝐑𝐂𝐄𝐒 𝐎𝐅 𝐂𝐀𝐑𝐁𝐎𝐍 𝐃𝐈𝐎𝐗𝐈𝐃𝐄:")` Carbon dioxide `color{red}((CO_2))` is released into the atmosphere by respiration, burning of fossil fuels for energy, and by decomposition of limestone during the manufacture of cement. It is also emitted during volcanic eruptions.
`color{green}(★)` Carbon dioxide gas is confined to troposphere only. Normally it forms about 0.03 % by volume of the atmosphere.
`color{green}(★)` Excess of `color{red}(CO_2)` in the air is removed by green plants and this maintains an appropriate level of `color{red}(CO_2) ` in the atmosphere. Green plants require `color{red}(CO_2)` for photosynthesis and they, in turn, emit oxygen, thus maintaining the delicate balance.
`color{green}(★)` The increased amount of `color{red}(CO_2)` in the air is mainly responsible for global warming.