Ozone (O3) is found throughout the entire atmosphere, although its concentration peaks are found in the stratosphere (15–50 km) and troposphere (0–15 km), with the stratospheric O3 layer having the highest percentage and concentrations. Even at relatively low quantities, ozone has an impact on both plants and animals. By harming the leaf, it prevents plant growth. Animals and humans may sustain damage to their respiratory systems. Reduced air pollution, especially nitrogen oxide and hydrocarbon emissions, is required to prevent an increase in ozone concentrations. This article will explain to you about Ozone which will be helpful in Environment Subject preparation for the UPSC Civil Service Exam.

Ozone

• Ozone (O3) is a colorless, reactive oxidant gas that is a major constituent of atmospheric smog.
• Both the upper atmosphere of the Earth and its surface are home to ozone, a gas made up of three oxygen atoms.
• Depending on where it is in the atmosphere, ozone can either be "good" or "bad" for the environment and your health.
• Even at low concentrations, the unpleasant, pale blue gas known as ozone is explosive and dangerous.
• In India, the ozone problem is essentially a "sunny weather concern," as sunlight directly affects the development of ground-level ozone.
• Photochemical processes are aided by the catalytic effect of heat. As a result, summertime is when ozone concentrations are at their highest.

Ozone Formed

• Ozone (O3) at the ground level is not directly emitted by human activity.
• It is a "secondary" pollutant that develops as a result of a complex series of chemical reactions when sunlight is present.
• The amount of ground-level O3 in the atmosphere is controlled by photochemical reactions of NOx and VOCs, which are mostly produced during combustion activities.
• Three reactions attain equilibrium and no net chemistry takes place under typical daytime conditions with a well-mixed environment.

What is good and bad ozone?

Good Ozone: Ozone is a good thing because it naturally occurs in the stratosphere, the highest atmosphere of the Earth, where it creates a barrier that protects us from the sun's harmful ultraviolet rays.

This protective barrier is destroyed and an ozone hole is created by ozone-depleting chemicals such as chlorofluorocarbons (CFCs), HCFCs, and halons.

The Kigali Amendment had been adopted by India (aims to phase-down hydrofluorocarbons).

Bad Ozone: When pollutants generated by vehicles, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight, ozone is formed in the lower atmosphere (troposphere) of the Earth, close to the ground.

Ozone at surface levels is a dangerous air contaminant.

How Ozone is an Air Pollutant?

• Ozone has negative effects on both people and the environment, ozone is a dangerous air pollutant at ground level and the primary component of "smog."
• In the atmosphere, ozone naturally forms. It exists because oxygen (O2) gets photo-dissociated into two oxygen atoms, one of which is energetically excited and can start a chain reaction that also involves nitrogen oxides and hydrocarbons.
• Before the industrial revolution, it only reached 0.02 ppmv or less in the lower troposphere (also known as surface ozone).
• Due to accelerated photo-oxidation brought on by rising NOx levels in the air, it has risen since the latter part of the 19th century, especially in industrialised areas.
• Concentrations in industrial locations are currently more or less 0.04 ppmv and in severely contaminated areas, they may briefly exceed 0.1 ppmv.
• Even at relatively low quantities, ozone has an impact on both plants and animals.
• By harming the leaf, it prevents plant growth. Animals and humans may sustain damage to their respiratory systems.
• Reduced air pollution, especially nitrogen oxide and hydrocarbon emissions, is required to prevent an increase in ozone concentrations.
• In affluent nations, this has had some success, but in many developing nations, high ozone concentrations are now also seen in areas with a lot of people.
• Although it fluctuates greatly in both location and time, the ozone concentration rises with height and reaches a maximum of roughly 1 ppmv in the stratosphere at elevations between 20 and 25 km.

Ozone Layer

• A natural gas barrier in the upper atmosphere called the ozone layer shields people and other living things from the sun's harmful ultraviolet (UV) radiation.
• Ozone (O3) exists in modest amounts throughout the atmosphere, but the majority of it (about 90%) is found in the stratosphere, a layer between 10 and 50 km above the earth's surface.
• The majority of the sun's biologically hazardous UV radiation is filtered away by this ozone layer, which serves a crucial function.

What Causes Ozone Layer to Deplete?

• Concentrations of ozone in the atmosphere vary naturally according to temperature, weather, latitude and altitude.
• Furthermore, substances ejected by natural events such as volcanic eruptions can have measurable impacts on ozone levels.
• However, natural phenomena cannot explain the current levels of ozone depletion.
• The scientific evidence shows that certain man-made chemicals are responsible for the creation of the Antarctic ozone hole and the global ozone losses.
• These chemicals are industrial gases which have been used for many years in a range of products and applications including aerosol sprays, refrigerators, air conditioners, fire extinguishers and crop fumigation.
• ODS(Ozone Depleting substances) are broken down by sunlight in the stratosphere, producing halogen (e.g. chlorine or bromine) atoms, which subsequently destroy ozone through a complex catalytic cycle.
• At the South Pole, where extremely low stratospheric temperatures throughout the winter form polar stratospheric clouds, ozone degradation is at its highest.
• These clouds' ice crystals increase the surface area available for chemical reactions, speeding up catalytic cycles.
• Since sunlight is used to destroy ozone, the process is accelerated during spring, when solar radiation levels at the pole are at their peak and polar stratospheric clouds are continuously present.

Ground Level Ozone

• Tropospheric ozone is produced by chemical interactions between nitrogen oxides (NOx) and volatile organic molecules (VOC).
• They are not directly released into the atmosphere.
• When sunlight is present, pollutants released from factories, power plants, industrial boilers, refineries, and other sources undergo chemical reactions.
• Ozone can still reach high levels throughout the colder months, although it is most likely to do so on hot, bright days in urban areas.
• Even in rural places, high ozone levels are possible due to the wind's ability to spread ozone across great distances.

Effects of Ground Level Ozone

• Inhaling ozone can result in a number of health issues, such as congestion, coughing, throat discomfort, and chest pain. It can make asthma, emphysema, and bronchitis worse.
• Ozone at ground level also impairs lung function and irritates the linings of the lungs. Repeated exposure may leave lung tissue irreversibly scarred.
• When exposed to ozone pollution, healthy people also have trouble breathing.
• Ground-level ozone harms ecosystems and vegetation, as well.
• Reduced development and survival of tree seedlings, decreased yields from agricultural crops and commercial forests, and greater susceptibility to diseases, pests, and other pressures like extreme weather are all results of it.

Measures to Counter Ground Ozone Depletion

Surface ozone concentrations in India are higher than the recommended limit of an 8-hour average of 100 g/m3, which is used to monitor air quality at various sites. Numerous health issues are brought on by surface ozone exposure at high levels.

The following are some of the actions the government has done to lessen ozone pollution:

• Switching from BS-IV to BS-VI certified automobiles.
• Burning of trash is forbidden.
• Action Plan for Graded Response (GRAP).
• The National Clean Air Programme has begun (NCAP).
• the establishment of a monitoring network to evaluate the ambient air quality at 779 sites, including 339 cities in 29 states and six union territories.

Stratospheric Ozone Layer

• The stratosphere produces ozone naturally. However, ozone-depleting substances (ODS) generated by humans, such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, and methyl chloroform, are slowly destroying this "good" ozone.
• Coolants, foaming agents, fire extinguishers, solvents, insecticides, and aerosol propellants all once employed these compounds also depletes the Layer.
• These ozone-depleting chemicals decay very slowly after being discharged into the atmosphere.
• They can endure the transition through the troposphere and into the stratosphere unharmed for years.
• The UV radiation from the sun breaks them down, releasing chlorine and bromine molecules that deplete the stratospheric ozone.
• One chlorine atom is thought to be capable of obliterating 100,000 molecules of ozone in the stratosphere.
• Even though we no longer use many ODS( Ozone Depleting Substances) , their historical use can still have an impact on the ozone layer's protective layer.
• According to research, there is a global decline in stratospheric ozone layer thinning. Satellite observations also detect ozone layer thinning over the Polar Regions.

Impacts on Stratospheric Ozone depletion

• Ozone depletion can increase the quantity of UV radiation that reaches Earth, which can raise the incidence of cataracts, skin cancer, and immune system impairment.
• Melanoma, the most lethal of all skin cancers, is thought to be on the rise as a result of excessive UV exposure. The likelihood of getting melanoma has more than doubled since 1990.
• UV exposure can also lower crop production and harm delicate crops like soybeans. According to some scientists, UV radiation is already stressing marine phytoplankton, the foundation of the ocean food chain.
• The human food supply that comes from the oceans may suffer as a result of this stress.

Measures to Counter Stratospheric Ozone Depletion

• A convention known as the Montreal Protocol was adopted in 1987 by more than 180 nations in order to gradually phase out the manufacture and use of ozone-depleting chemicals in response to the concerns posed by ozone depletion.
• Following this, negotiations were on to regulate anthropogenic (ODSs) and certain hydrofluorocarbon production and consumption through the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer and its ensuing amendments (HFCs).
• Hydrochlorofluorocarbons (HCFCs) and afterwards HFCs are two compounds that need to be replaced, according to the Montreal Protocol, in a variety of industrial sectors.
• HFCs have a little impact on stratospheric ozone, yet some of them are potent greenhouse gasses (GHGs).
• India is one of the few nations in the world and, in some circumstances, a pioneer in the adoption of technology that does not deplete the ozone layer and has minimal global warming potential (GWP).
• India has actively opted to transition away from ozone depleting substances and toward environmentally and energy-friendly technologies (ODSs).
• Hydrochlorofluorocarbon (HCFC)-141 b, one of the most potent ozone depleting chemicals after Chlorofluorocarbons (CFCs) (HCFC)-141 b is used primarily as a blowing agent in the production of stiff polyurethane (PU) foams, has been completely phased out in India with success.

Ozone pollution effects

Health

• The respiratory system may become irritated, which can cause coughing and an uneasy feeling in the chest.
• Ozone worsens bronchitis, emphysema, asthma, and other conditions, raises the likelihood of lung inflammation, such as Chronic Obstructive Pulmonary Disease, and increases susceptibility to it (COPD).
• It could weaken lung capacity and make breathing challenging.

Environment

• UV alterations development, food chains, and metabolic processes in terrestrial and aquatic environments.
• High UV radiation has a negative impact on aquatic life, especially that which is found just below the water's surface and is the foundation of the food chain.
• Additionally, UV rays have a negative impact on plant growth, which lowers agricultural productivity.
• Additionally, as stratospheric ozone is lost, the temperature of the atmosphere changes, having a range of environmental and climatic effects.

Economic Impacts

• The most significant direct economic impact of increased UV radiation is an increase in health care expenses.
• Health care systems, particularly in less developed nations, are challenged by the costs of treating millions of cases of skin cancer and cataracts.
• The lifespan and tensile characteristics of some polymers and fibers are also decreased by increased UV light.
• Additional expenses, such as those incurred in the fight against climate change or as a result of depleted fish stocks, are examples of indirect economic impacts.

Montreal Protocol on Ozone Depleting substances

• A global agreement called the Montreal Protocol on Substances that Deplete the Ozone Layer aims to protect the ozone layer of the Earth by gradually banning the substances that damage it.
• The production and consumption of ozone-depleting chemicals are both covered by this phase-out strategy.
• The historic pact was signed in 1987 and came into effect in 1989.
• Once a year, the parties to the Protocol get together to make decisions that will help the agreement be carried out successfully.
• Adjusting or revising the Protocol, which has been done six times since its inception, is one of them.
• Hydrofluorocarbons (HFCs) were to be phased down starting in 2016 according to the most recent revision, the Kigali Amendment.

Conclusion

In order to reduce ozone pollution, we must reduce overall pollution through interventions like the implementation of BS-VI standards for vehicles, the expansion of public transportation, the switch to cleaner fuel in industries, and the promotion of activities like cycling and walking.

FAQs

MCQs

1. Which of the following particles is most harmful to human health?

A) PM10

B) PM2.5

C) PM5

D) PM8

2. Which of the following is a major natural source of Suspended Particulate Matter (SPM)?

A) Industrial emissions

B) Power plant emissions

C) Wildfires

D) Vehicular exhaust

3. Which of the following activities contributes the most to the formation of SPM in urban areas?

A) Vehicular emissions

B) Agricultural practices

C) Industrial processes

D) Both A and C

4. What is the impact of PM2.5 on human health?

A) Causes asthma

B) Leads to heart disease

C) Can cause lung cancer

D) All of the above

5. Which of the following measures can help reduce the levels of Suspended Particulate Matter (SPM)?

A) Using more coal for energy

B) Promoting the use of cleaner technologies in vehicles

C) Reducing tree cover

D) Encouraging the burning of biomass

GS Mains Questions and Model Answers

Q1: Discuss the health and environmental impacts of Suspended Particulate Matter (SPM) in urban India.

Answer: Suspended Particulate Matter (SPM) is a critical environmental and health issue in urban India. Urban areas, with their high population density, industrial activities, vehicular emissions, and construction work, experience elevated levels of SPM, particularly PM2.5. These fine particles have severe health consequences, including respiratory diseases, cardiovascular conditions, lung cancer, and aggravated asthma. Long-term exposure to high levels of SPM is associated with premature deaths and reduced life expectancy. Environmentally, high concentrations of SPM reduce air quality, affect visibility, and contribute to acid rain, harming vegetation and aquatic ecosystems. Effective regulation, urban planning, and adoption of cleaner technologies are essential to mitigate these harmful effects.

Q2: Evaluate the role of government policies in controlling the levels of SPM in major cities in India.

Answer: Government policies play a vital role in controlling the levels of Suspended Particulate Matter (SPM) in Indian cities. Initiatives like the National Clean Air Programme (NCAP), aimed at reducing air pollution, focus on curbing emissions from industries, vehicles, and construction activities. The implementation of stricter emission standards for vehicles, promoting the use of cleaner fuels, and encouraging the shift to electric vehicles are crucial measures. Additionally, governments have introduced regulations to limit industrial emissions and construction dust. However, these efforts need to be backed by public awareness campaigns, better monitoring systems, and enforcement of air quality standards. Despite progress, challenges such as rapid urbanization and inadequate infrastructure remain obstacles to controlling SPM levels effectively.

Q3: What measures can individuals take to minimize exposure to Suspended Particulate Matter (SPM)?

Answer: Individuals can take several measures to minimize exposure to Suspended Particulate Matter (SPM). These include staying indoors during high pollution periods, using air purifiers, wearing masks that filter fine particles, and avoiding outdoor physical activities in areas with high SPM concentrations. People can also reduce their personal carbon footprint by using public transport, switching to electric vehicles, and reducing energy consumption. Supporting policies and initiatives aimed at controlling air pollution, such as promoting clean energy and reducing industrial emissions, also contributes to broader efforts to reduce SPM levels. Education and awareness play an important role in encouraging communities to take action against air pollution.

Previous Year Questions on Suspended particulate matter

1. UPSC CSE 2022:

Question: Examine the role of particulate matter in urban air pollution and its impact on human health and the environment.

Answer: Particulate matter, especially PM2.5 and PM10, is a major contributor to air pollution in urban areas. The high concentration of these fine particles in the air causes significant health risks, including respiratory diseases, heart conditions, and premature mortality. Environmentally, particulate matter contributes to reduced visibility, acid rain, and environmental degradation. The government’s initiatives like stricter emission standards and the promotion of clean energy are essential to combat the adverse effects of particulate matter.

2. UPSC CSE 2020:

Question: Discuss the factors contributing to the rising levels of particulate matter in the air and its implications for public health.

Answer: The increasing levels of particulate matter, particularly PM2.5, are due to a combination of factors, including vehicular emissions, industrial pollution, construction activities, and agricultural residue burning. These sources release large quantities of particulate matter into the atmosphere, causing significant air quality deterioration. The implications for public health are severe, including an increase in respiratory diseases, cardiovascular diseases, and a reduction in life expectancy. The need for stronger regulations and public awareness on air pollution control is critical in addressing this issue.