Chapter 14: Atmosphere

Naturally occurring particulate matter (PM) include dust from earth's surface, and biological materials in the form of pollens, spores and animal debris. • Volcanic eruptions can introduce very a vee. large quantities of gases and particulate matter (PM) into the atmosphere. significant • Thunderbolt produces quantities of oxides of nitrogen (NOx). • Other natural sources of air pollution are algae on the surface of the oceans, which gives out hydrogen sulfide (HS), wind erosion. PM which introduces (particulate matter). • Humid zones such as swamps, peat-bags or little deep lakes, which produce methane (CH4).

Deforestation is purposeful cleaning or thinning of forests by humans. Forests absorb Green House Gases (GHGs) like CO2 and clean air for us. So deforestation deteriorate the air quality. Deforestation has a wide range of negative impact on the environment, including loss of soil change, biodiversity, climate degradation and water cycle disruption.

Troposphere In the troposphere temperature decreases with increases moving upwards in altitude this is because of decrees in concentration of gases atmospheric responsible of temperature maintenance on earth. It's range is from 17°C to -58°C. Stratosphere When we move up in the stratosphere temperature increase with the increase of altitude this is because of presence of ozone layer as ozone formation is an exothermic reaction. It's range is - 58°C to -2°C.

See Q3. and Q4. from theory. Write short notes

Pollutant released Activity Power stations Sulfur dioxide Automobiles Nitrogen dioxide Livestock and cattle Ammonia Metallurgy Heavy metals

See Q3. and Q7. from theory.

Persistent Organic Pollutants (POPs): These are organic compounds that are resistant to degradation through and photolytic chemical, biological processes. These are toxic and adversely affect human health and the environment, traveled by wind and water. Most POPs are generated in one country can affect people and wildlife far from where they are used and released. Owing to their in the accumulate persistence, they environment Effects: POP's can have significant adverse effects on human health. Polychlorinated Biphenyls Examples: (PCBs), Dichlorodiphenyl trichloroethane (DDT).

See Q7. from theory.

Polycyclic Aromatic Hydrocarbon (PAHs) Polycyclic aromatic hydrocarbon (PAHs), composed of fused multiple aromatic rings are common environmental pollutants. Effects on health: They have potential toxicity and carcinogenic properties. Examples: Naphthalene, anthracene and phenanthrene.

See Q8. from theory.

Photochemical smog: Photochemical smog is a type in which primary air pollutants like nitrogen oxides (NOx), VOCs and unburned hydrocarbons undergo photochemical reactions in the presence of sunlight and form secondary pollutants like ozone and peroxyacetyl nitrates (PAN). Conditions: Presence of sunlight, presence volatile organic compounds, presence of oxides of nitrogen and less movement of wind.

AQI systems provide data about presence and concentration of different air pollutants. These pollutants can include particulates matter (PM), nitrogen dioxides (NO2), sulfur dioxide (SOz), carbon monoxide (CO), ozone (O3) and volatile organic compounds (VOCs). This data can be further used to for policies and make laws to reduce pollution.

PMio and P.M2.5 refers to the size of matter while PM2.5 particulate 2.5micrometer or less while PMio is 10 micrometer or less PM2.s is considered more harmful due to its small size which allows these particles to penetrate deep inside the human respiratory system without being hindered by natural protective mechanisms.

Chemical reaction: The most important chemical reactions are following: → 250 3(g) 2502(g) +0281 SO 3(8) + HO (1) → H, SO A (an) SO2 from fossil fuels is oxidized to SO3 which then reacts with water to form sulphuric acid. SLO BASED SHORT QUESTION ANSWERS

Specific measures to control smog particularly during the winter months when air quality deteriorates significantly, Restrictions the burning of crop residues, which is a major contributes to smog, use smog towers and technologies to reduce particulates matter in the air

other Oxides of nitrogen 1S undesirable gases such as CO and various unburnt hydrocarbon are emitted by the vehicle engines. The most cars are equipped with catalytic convertors to convert the harmful pollutants to harmless substances. CO is oxidized to CO2. NOx are reduced to N2. The unburnt hydrocarbon is converted to CO2 and H2O.

Heavy metal like lead, mercury and cadmium can indeed be significant air into the pollutants. They are released atmosphere from various industrial process, transportation and other human activities. Major sources: Metallurgy, battery waste and incineration. 16 km. It contains most of the atmospheric mass and almost all water vapor. Whether phenomena like clouds, rain, and storms occur here. Temperature decreases with altitude in this layer.

The troposphere is the lowest layer of the atmosphere, extending up to about 8- → 2N0 242) 3NO 2(g) + H2O(e) 2HNO3(ag) + NO Nitrogen oxide reacts with water to produce nitric acid and nitrous acid

The stratosphere lies above the troposphere, up to about 50 km altitude. It contains the ozone layer, which absorbs harmful ultraviolet radiation. Unlike the troposphere, its temperature increases with height due to UV absorption. This layer is important for protecting life from UV damage.

The mesosphere extends from about 50 km to 80 km above the Earth. It is the coldest layer of the atmosphere, with temperatures dropping to -90°C. Most meteoroids burn up here due to atmospheric friction. The boundary at its top is called the mesosphere.

The exosphere is the outermost layer of the atmosphere, extending from about 500 km to thousands of kilometres. Air is extremely thin here and molecules can escape into space. It mainly contains hydrogen and helium atoms. This layer gradually merges with outer space. Composition of the atmosphere

Dry air is composed mainly of nitrogen (78%) and oxygen (21%), with argon (0.93%) as the next most abundant gas. Carbon dioxide makes up about 0.04%. Trace gases like neon, helium, methane, and ozone are present in smaller amounts.

Nitrogen is inert and makes up the largest portion of the atmosphere. It dilutes oxygen, preventing rapid combustion. It is also essential for living organisms as it is a key element in amino acids and proteins, entering the food chain through nitrogen fixation.

Water vapor is important for cloud formation and precipitation. It absorbs heat and contributes to the greenhouse effect. It plays a key role in the Earth's energy balance and whether systems. Its amount varies with temperature and location. Sources and types of air pollutants

Primary pollutants are emitted directly into the atmosphere from sources natural and like vehicles, industries, processes. Examples include CO, SO2, NO, and particulate matter They can harm human health and the environment directly.

propellants for aerosols and as coolant in refrigerators and air conditions. CFCs are 100,000 times more effective than CO2 at preventing heat from escaping from the Earth's atmosphere. The decomposition of one molecule of CFC's can destroy up to 100,000 molecules of ozone. CFCe, -Ur ›CFCl, +Cl ClO+O→Ce+ 02

Secondary pollutants are not emitted directly; they form in the atmosphere by chemical reactions of primary pollutants. Examples include ground-level ozone and peroxyacetyl nitrates (PANs). Sunlight often drives these reactions, as in photochemical smog.

Human-made vehicle exhaust, industrial emissions, burning of fossil fuels, and agricultural activities. These release pollutants like CO2, NOx, SO2, and particulates into the atmosphere. They are major contributors to urban smog and climate change.

Particular matter (PM) consists of tiny particles suspended in the air, including dust, dirt, soot and smoke ranging from of 2.5 micrometer diameter to 10.0 micrometer. Inhalation of these particulate matter (PM) can cause inflammation and irritation of airways, leading to conditions such as asthma and bronchitis.

The short-term exposures of NO2 and SO2 can irritate the respiratory system, long term exposure increase the risk of respiratory infection, asthma and bronchitis.

Chlorofluorocarbons are used propellants for aerosols and as coolant in refrigerators and air conditions. CFCs are 100,000 times more effective than CO2 at preventing heat from especially from the earth's atmosphere. The decomposition of one molecule of CFCs can destroy up to 100,000 molecules of ozone. are

Anthropogenic activities are human- made actions or processes that affect the natural environment. The term comes from "Anthropos" (Human) "genic" (produçed by): These activities can have positive or negative impacts on ecosystems, climate and the Earth's resources. between dry

Wet deposition Dry deposition Wet deposition refers Direct deposition is transfer transfer of pollutants from air to surface of pollutants to land via by absorbing precipitation gravity or wind Oxides of carbon 030. What is carbon monoxide and why is it harmful? Ans. Carbon monoxide is a colourless, odourless gas produced by incomplete combustion of carbon fuels. It binds to haemoglobin more strongly than oxygen, reducing oxygen transport in the body. High exposure can cause death.

CO emissions can be reduced by improving combustion efficiency, using catalytic converters in vehicles, ensuring proper ventilation for gas appliances, and shifting to cleaner fuels. Public awareness is also important.

Carbon monoxide is highly gas and cause suffocation if poisonous inhale. It binds blood hemoglobin more strongly than oxygen thus excluding oxygen from normal respiration. The CO poisonous can be reversed by giving high pressure oxygen. Oxides of nitrogen

Nitrogen oxides include NO and NO2, produced mainly during high- temperature combustion. They are important air pollutants contributing to smog and acid rain. Natural sources include lightning and soil bacteria.

NOz irritates the respiratory system, reducing lung function and aggravating asthma. Long-term exposure can lead to chronic respiratory diseases. It also contributes to the formation of ground-level. ozone.

The main human source is combustion in vehicles, power plants, and industries. High temperatures cause nitrogen and oxygen in air to react, producing NO and NO2. 036. There is large amount of oxygen and nitrogen in atmosphere why they don't react to form oxides of nitrogen? Ans. Because reaction of oxygen and nitrogen requires large amount of energy ordinarily not available in atmosphere. N2(g) +02(g) High temp. → 2 NO (g) (Nitric oxide) 2N0(8) + 0z 2NO, (Nitrogen-Dioxide)

Emissions can be controlled by catalytic converters in vehicles, using low- to cleaner NOx burners, and switching energy sources. Regulations and fuel quality improvements also help. Ozone causes

Ozone depletion is mainly caused by chlorofluorocarbons (CFCs) and other halogenated compounds. These release bromine atoms in and the chlorine stratosphere, which destroy ozone molecules.

depletion radiation reaching Earth, causing skin cancer, cataracts, and immune suppression. It also harms crops and marine life, especially phytoplankton.

Ground-level ozone is a secondary pollutant formed from NOx and VOCs in sunlight. It irritates the lungs, reduces crop yields, and damages materials like rubber.

It can be reduced by phasing out under substances ozone-depleting agreements like the Montreal Protocol. Using alternatives to CFCs and improving refrigeration technology are important measures.

The layer where the maximum concentration of ozone is present is called ozone layer. It is present in the 2nd layer of atmosphere that is "Stratosphere"

The region where the ozone layer depletes called ozone hole. Especially over the Antarctic region during the southern Hemisphere's spring (August to October). Acid rain

Acid rain is rain with pH below normal (less than 5.6) due to dissolved acids like H2SO4 and HNO. It results from SO2 and NOx emissions reacting with water in the atmosphere.

Acid rain lowers the pH of lakes and rivers, harming fish and other aquatic organısms. Many species cannot survive in to acidic reduced water, leading biodiversity. can acid rain be

Controlling acid rain reducing SOz and NOx emissions using scrubbers, catalytic converters, and cleaner fuels. International cooperation is essential since pollutants can travel long distance

Photochemical smog forms when sunlight drives reactions between NOx and VOC's, producing ozone and PANs. It is common in sunny cities with heavy traffic.

Industrial smog forms from burning coal and oil in cool, humid conditions. It • water droplets, contains SO2, soot, and giving it a grey colour. It was historically common in cities like London. Air quality 049. What is the Air Quality Index (AQI)? The AQI is a scale that indicates how Ans. polluted the air is and the associated health risks. It is calculated using concentrations of pollutants like PM of size 2.5um and PM of size 10 um, SO2, NOz, CO, and O3. 050. What do you mean by high risk population? Ans. Children under 18, adult over 65, people with chronic heart, and lung diseases more as they are are under high-risk, vulnerable to harmful effects of air pollution. Outdoor workers are at higher risk because of the prolonged exposure Reduce Air Pollution

Following hypothesis will be made "The concentration of airborne particulate matters (PM 2.5) and nitrogen dioxide (NO2) in urban areas is higher during peak traffic hours as compared to non-peak hours" Advantage • Formulating a hypothesis is the first step in designing the experiment. • This hypothesis can be tested by collecting air quality, data at different time of the day. DESCRIPTIVE QUESTIONS (EXERCISE)

Air pollution is not confined to borders and effective management requires international cooperation. Because polluted air of one country can affect the air quality of other countries.

Busy roads sites and residential areas should be selected for monitoring. The data on traffic volume during rush hours and non-rush hours should be collected and finally compared. The reliable instruments and methods to collect air quality data should be used.

By carefully designing experiments, collecting and analyzing data, a hypothesis about air quality can be tested and the strategies for improving air quality can be made.

Analyzing and interpreting air quality data involves understanding the of various concentration pollutants, identifying trends overtime and assessing the implications for public health and environmental policy.