How Is Photochemical Smog Formed

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How Is Photochemical Smog Formed?

Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight creating a brown haze above cities. It tends to occur more often in summer because that is when we have the most sunlight.

What is photochemical smog how is it formed and how does it effect?

Photochemical smog is a type of smog produced when ultraviolet light from the sun reacts with nitrogen oxides in the atmosphere. It is visible as a brown haze and is most prominent during the morning and afternoon especially in densely populated warm cities.

What is the main cause of photochemical smog?

Photochemical smog is produced when sunlight reacts with nitrogen oxides and at least one volatile organic compound (VOC) in the atmosphere. Nitrogen oxides come from car exhaust coal power plants and factory emissions. … When sunlight hits these chemicals they form airborne particles and ground-level ozone—or smog.

How is photochemical smog formed quizlet?

Photochemical smog is formed when nitrogen oxides (NOx) and volatile organic hydrocarbons react when activated by sunlight. … 3) When exposed to UV radiation from the sun some NO2 reacts with hydrocarbons to form photochemical oxidants such as ozone nitric acid aldehydes and other pollutants.

Which gas is formed in photochemical smog?

Among the pollutants involved in photochemical smogs are ozone nitrogen dioxide and peroxyacyl nitrate (PAN). The nitrogen dioxide and other oxides of nitrogen are primary pollutants produced by dissociation in combustion reactions and both ‘prompt’ and ‘thermal’ NOx can be involved in the reactions.

How is ozone formed in photochemical smog?

VOCs + NOx = Ozone. These volatile organic compounds react to form ozone only in the presence of sunlight. … This blue light is producing the UV light that is required to create ozone. And this ozone again reacts with volatile organic compounds to produce photochemical smog.

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How are solid particulates formed?

1.2 How are particles formed? Coarse particles are produced by the mechanical break-up of larger solid particles. The coarse fraction can include dust from roads agricultural processes uncovered soil or mining operations as well as non-combustible materials released when burning fossil fuels.

What is a photochemical smog quizlet?

Photochemical smog is a mixture of about one hundred primary and secondary pollutants formed under the influence of sunlight. Ozone is the main pollutant. Precipitation cleans the air and winds disperse the smog.

How is photochemical smog formed what secondary pollutant is a major component?

Smog forms when sunlight nitrogen oxides and volatile organic compounds are present. The secondary pollutant ozone is a major component of photochemical smog. … Acidic desposition which is comprised of hydrogen sulfate and nitrate ions forms from both sulfur dioxide and nitrogen oxides.

What is the formation of smog?

Formation. Smog forms when pollutants are released into the air. The pollutants are formed both naturally and by humans however the human-induced pollutants are of most concern due to the magnitude of pollutants produced by the burning and extraction of fossil fuels which are known to cause extreme health effects.

What are the component of photochemical smog?

The major undesirable components of photochemical smog are nitrogen dioxide (NO2) ozone (O3) PAN (peroxyacetylnitrate) and chemical compounds that contain the –CHO group (aldehydes). PAN and aldehydes can cause eye irritation and plant damage if their concentrations are sufficiently high.

What is photochemical smog list the factors that favor the formation of photochemical smog?

Photochemical smog development factors

1-Nitrogen source and released organic combinations combining high density of this material with industrializing and transportation are important factors forming photochemical smog. These factors cause some pollution to form in atmosphere by combustion fossil fuel.

What is the relationship between tropospheric ozone and photochemical smog formation?

When NOx and volatile organic compounds (VOCs) react in the presence of sunlight they form a photochemical smog which is a significant form of air pollution [17] . Nitrogen oxides also play an important role in the atmospheric reactions creating ozone and acidic rain by the formation of nitric acid. …

What is photochemical ozone formation?

Bioeconomy. Impact category that accounts for the formation of ozone at the ground level of the troposphere caused by photochemical oxidation of Volatile Organic Compounds (VOCs) and carbon monoxide (CO) in the presence of nitrogen oxides (NOx) and sunlight.

What is an photochemical smog ozone?

Photochemical smog consists of ozone (O3) and other closely related species (“secondary pollutants”) that are produced photochemically from directly emitted species in a process that is driven by sunlight and is accelerated by warm temperatures.

How are carbon particulates formed?

Incomplete combustion of a hydrocarbon fuel occurs when there is not enough oxygen for complete combustion caused by a poor supply of air. Less energy is released. Instead of carbon dioxide you might get carbon monoxide or particulate carbon known commonly as soot or a mixture of both.

What causes PM10 pollution?

Emissions from combustion of gasoline oil diesel fuel or wood produce much of the PM2. … PM10 also includes dust from construction sites landfills and agriculture wildfires and brush/waste burning industrial sources wind-blown dust from open lands pollen and fragments of bacteria.

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How is carbon monoxide formed?

Thermal combustion is the most common source for carbon monoxide. Carbon monoxide is produced from the partial oxidation of carbon-containing compounds it forms when there is not enough oxygen to produce carbon dioxide (CO2) such as when operating a stove or an internal combustion engine in an enclosed space.

What does VOCs stand for ESS?

Volatile Organic Compound (VOCs)

What is smog quizlet?

-Smog: a poisonous mixture of smoke aire and other pollutants. -need: emissions warmth/sunlight and no air movement.

What is industrial smog?

Both industrial smog and photochemical smog are forms of air pollution. … Industrial smog typically exists in urban areas where factories burn fossil fuels such as coal which creates smoke and sulfur dioxide that mix with fog droplets to create a thick blanket of haze close to the ground.

Why is photochemical smog a secondary pollutant?

An important secondary pollutant for photochemical smog is ozone which is formed when hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight nitrogen dioxide (NO2) which is formed as nitric oxide (NO) combines with oxygen (O2) in the air.

Which pollutant is the major contributor to photochemical smog?


Option 2 is the correct answer: Ozone is the major contributor to photochemical smog.

Is photochemical oxidants present in photochemical smog?

Photochemical oxidants are found in ‘photochemical smog’ which is a complex mixture of primary and secondary air pollutants. The photochemical oxidants are secondary air pollutants formed by the action of sunlight on nitrogen oxides and reactive hydrocarbons their precursors.

What is photochemical pollution?

Photochemical air pollution is pollution caused by the reaction of unsaturated and saturated hydrocarbons aromatics and aldehydes (emitted owing to the incomplete combustion of fuels) with light. It causes eye irritation.

Which is the secondary precursor of photochemical smog?

The primary precursors of photochemical smog are NO2 and hydrocarbons and the secondary precursors are ozone and PAN.

Where does photochemical smog occur?

Photochemical smog which is also known as “Los Angeles smog ” occurs most prominently in urban areas that have large numbers of automobiles. It requires neither smoke nor fog. This type of smog has its origin in the nitrogen oxides and hydrocarbon vapours emitted by automobiles…

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What are the factors affecting the formation and severity of photochemical smog?

U5 The frequency and severity of smog in an area depends on local topography climate population density and fossil fuel use. Photochemical smog is a mixture of about one hundred primary and secondary pollutants formed under the influence of sunlight. Ozone is the main pollutant.

What are the ingredients and conditions leading to the formation of photochemical smog are all the ingredients from what are commonly regarded as pollution sources?

The formation of photochemical smog consists of three main ingredients. Moreover these ingredients are nitrogen oxides hydrocarbons and sunlight. Nitrogen oxides and hydrocarbons are the by-products of fossil fuels-burning energy plants. Furthermore they can also come from natural processes.

Is formaldehyde a component of photochemical smog?

The common components of photochemical smog are ozone nitric oxide acrolein formaldehyde and peroxyacetyl nitrate (PAN).

What is the difference between photochemical smog and industrial smog?

It is produced when nitrogen oxides and volatile organic compounds in automobile and fossil-fueled power-plant emissions combine with oxygen in the air in direct sunlight. Whereas industrial smog casts a gray pallor over the areas it affects the nitrogen dioxide in photochemical smog creates a dingy brownish haze.

Which one is not related to photochemical smog formation?

Hence chlorofluorocarbons are not common component of photochemical smog.

What creates tropospheric ozone?

Tropospheric or ground level ozone is not emitted directly into the air but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC).

What is acidification potential?

Acidification potential refers to the compounds that are precursors to acid rain. These include sulfur dioxide (SO2) nitrogen oxides (NOx) nitrogen monoxide (NO) nitrogen dioxide (N2O) and other various substances. Acidification potential is usually characterized by SO2-equivalence.


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