#air pollution

Applied Ecology

Which is the correct sequence of smog formation?

Photochemical smog follows the pathway nitrogen oxides plus VOCs plus sunlight leading to ozone and PAN. Nitrogen dioxide absorbs light and yields the atomic oxygen needed for ozone formation; VOC oxidation generates peroxy radicals that convert nitric oxide back to nitrogen dioxide without removing ozone. Acyl peroxy radicals combine with nitrogen dioxide to form peroxyacyl nitrates. The other proposed sequences omit essential photochemistry or combine unrelated substances. Atmospheric inversions can trap contaminants near the surface, while wind, turbulence, precipitation, and chemical trans

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which component of smog causes eye irritation?

Peroxyacetyl nitrate, commonly represented within the broader term PAN, is a secondary component of photochemical smog and a powerful lachrymator. It forms when VOC oxidation products react with nitrogen dioxide and can irritate conjunctival and respiratory tissues. Carbon monoxide mainly produces systemic hypoxia without being a strong eye irritant, while lead and mercury are toxic metals rather than characteristic lachrymatory smog components. Exposure depends on concentration, duration, ventilation, weather, and individual susceptibility, so a pollutant's presence alone does not fully predi

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which pollutant causes Taj Mahal discoloration?

Sulfur dioxide from refineries, combustion, and other sources around Agra contributes to marble deterioration and discoloration. Atmospheric oxidation produces sulfuric acid and sulfate; these react with calcium carbonate in marble to form gypsum, which is more soluble and traps soot and dust, creating a yellowed or darkened surface. Nitrogen oxides and particulates may contribute, so attributing all damage exclusively to one pollutant is a simplification. Atmospheric inversions can trap contaminants near the surface, while wind, turbulence, precipitation, and chemical transformation determine

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which of the following is a primary air pollutant?

Nitric oxide is emitted directly during high-temperature combustion when atmospheric nitrogen and oxygen react, making it a primary pollutant. Once released, it is oxidised to nitrogen dioxide and participates in photochemical cycles. Ozone and peroxyacyl nitrate, including PAN, arise through atmospheric reactions involving nitrogen oxides, volatile organic compounds, and sunlight, so they are secondary pollutants. Exposure depends on concentration, duration, ventilation, weather, and individual susceptibility, so a pollutant's presence alone does not fully predict biological harm. Atmospheric

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which air pollutant is known to displace oxygen in blood?

Carbon monoxide causes functional oxygen deprivation by competing with oxygen for haemoglobin and forming carboxyhaemoglobin. Its very high binding affinity reduces the number of sites available for oxygen and impairs unloading from the remaining oxyhaemoglobin. The phrase 'displace oxygen' is a physiological shorthand: carbon monoxide does not remove dissolved oxygen directly, but sharply lowers the blood's effective oxygen-carrying and delivery capacity. The distinction is ecologically important because emission control must target either the directly released precursor or the product formed

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

The major source of anthropogenic CO emission is:

Road vehicles are a major anthropogenic source of carbon monoxide because petrol and other carbon fuels undergo incomplete combustion when oxygen supply, mixing, temperature, or residence time is inadequate. Urban traffic therefore produces high exposures near roads, particularly from poorly maintained engines and congestion. Power stations generally achieve more complete, controlled combustion and are more strongly associated with carbon dioxide, sulfur oxides, nitrogen oxides, and particulates. Effective management combines cleaner fuels, emission standards, monitoring, urban planning, and p

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which oxide is primarily responsible for acid rain?

Sulfur dioxide is a principal precursor of acid rain, especially where sulfur-containing coal and oil are burned. In the atmosphere it is oxidised to sulfuric acid and sulfate, which return through wet or dry deposition. Nitrogen oxides also form nitric acid and contribute significantly, but among the listed single oxides sulfur dioxide is the standard principal association. Sound classification links the source, atmospheric fate, exposure route, and mechanism of toxicity rather than relying only on the pollutant's name. Effective management combines cleaner fuels, emission standards, monitori

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which particulate matter is most harmful due to deep penetration in lungs?

PM2.5 comprises particles with aerodynamic diameters at or below 2.5 micrometres. Their small size allows them to evade much of the upper respiratory filtration, penetrate into bronchioles and alveoli, and in some cases contribute components to systemic circulation. PM10 includes larger particles that are more often deposited in the nose and conducting airways, although it also remains harmful. At organismal level, respiratory surfaces are especially exposed because large volumes of air contact thin, moist epithelia designed for rapid gas exchange. Sound classification links the source, atmosp

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which of the following is a reducing smog?

Classical London smog is called reducing smog because it forms under cool, humid conditions from coal smoke, sulfur dioxide, and reducing particulate material. Fog droplets promote sulfur chemistry and trap soot near the ground during temperature inversions. Los Angeles or photochemical smog is instead strongly oxidising because sunlight generates ozone, peroxyacyl nitrates, and other photochemical oxidants. Atmospheric inversions can trap contaminants near the surface, while wind, turbulence, precipitation, and chemical transformation determine their eventual distribution and removal. At orga

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which of the following is a secondary pollutant?

Tropospheric ozone is formed in air rather than emitted directly in substantial amounts, so it is classified as a secondary pollutant. Sunlight photolyses nitrogen dioxide, and the liberated oxygen atom combines with molecular oxygen to produce ozone; VOC chemistry permits its net accumulation. Carbon monoxide, nitric oxide, and sulfur dioxide are commonly released directly from combustion and are primary pollutants. Exposure depends on concentration, duration, ventilation, weather, and individual susceptibility, so a pollutant's presence alone does not fully predict biological harm. Atmospher

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Which gas is a major component of Los Angeles-type smog?

Los Angeles-type smog is oxidising photochemical smog, and ground-level ozone is one of its major components. Strong sunlight drives reactions among nitrogen oxides and volatile organic compounds emitted chiefly by traffic and industry. Sulfur dioxide is more characteristic of traditional coal-smoke or London smog, whereas carbon monoxide may be present but does not define this smog type. The distinction is ecologically important because emission control must target either the directly released precursor or the product formed after atmospheric transport and reaction. Exposure depends on concen

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Applied Ecology

Photochemical smog is mainly caused by the reaction of VOCs with which compound?

Photochemical smog develops when volatile organic compounds react through radical chemistry with nitrogen oxides in sunlight. Nitrogen dioxide photolysis releases oxygen atoms that form ozone, while reactions involving VOC-derived peroxy radicals regenerate nitrogen dioxide without consuming ozone. The resulting mixture includes ozone, aldehydes, and peroxyacyl nitrates rather than being a simple accumulation of primary emissions. Effective management combines cleaner fuels, emission standards, monitoring, urban planning, and protection of populations with high exposure or physiological vulner

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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