50% of Carbon monoxide emissions are from automobiles. Normally CO has a brief residence in atmosphere and gets oxidized to co2. However, in congested and closed areas if proves quite harmful. Carbon monoxide combines with haemoglobin, produces carboxyhaemoglobin or COHb. At 50 ppm, CO converts 7.5% of haemoglobin into carboxyhemoglobin within 8 hours. It impairs oxygen transport resulting in giddiness, headache, decreased vision, cardiovascular malfunction, and asphyxia.

• Its composition is propane or butane or a mixture of both, are flammable mixtures of hydrocarbon gases used as fuel in heating appliances, cooking equipment, and vehicles.
• Use of LPG is not a method to control air pollution because Inhaling of LPG vapour can cause irritation in nose and throat, headache and nausea, vomiting, dizziness and loss of consciousness.
  
• Hence Use of LPG gas is not a method to control air pollution.
• So, the correct answer is 'Use of LPG gas'.

• Asthma is a condition in which a person's airways become inflamed, narrow and swell and produce extra mucus, which makes it difficult to breathe.
• The symptoms of asthma often present in periodic attacks or episodes of tightness in the chest, wheezing, breathlessness, and coughing.
• Asthma is caused by many reasons such as air pollution, smoking, dust, pets, chemicals, and genetic reasons. Allergins present in the polluted air causes an inflammatory reaction is airways which leads to asthma.
• Hence Asthma can be caused by air pollution.
• So, the correct answer is 'Air pollution'.

Most of the automobiles have an environmental impact up to 80 to 90 percent., It is due to fuel consumption and emissions of air pollution and greenhouse gases that are said to drive global warming.

People also should take initiative to reduce air pollution like 

On burning, fossil fuel with minimum oxygen supply is given unburn carbon particle which doesn't settle down and get mix with water vapour. In winter it gets worse, visibility of air get dropdown and very hard to breath because of a minute particle present in the air. Sulphur and Nitrogen are also harmful but they are not involved in visibility problem.

Air pollution means the presence of gases, dust particles, fumes, smokes, harmful chemicals in the atmosphere such that that makes it harmful to other living beings. Causes of air pollution includes:

There are various man-made factors that create the environmental problems. These factors include air pollution, degradation of air, water contamination, over population, industrial mining, climate change, deforestation, fossil fuels, fertilizer use, etc. The natural factors responsible for environmental problems include forest fire, water vapour, frost soil, etc.

ESP or electrostatic precipitators are used to remove dust particles from flue gas (such as gas from broilers). The dust particles present in the air get charged as they pass through the electrostatic precipitator and get collected at the collection electrode. It can, therefore, be used to remove air pollutants such as dust. 

Coal usually produces a lot of smoke. So, when burning indoor it creates a lot of chemical pollution.

Vehicle emissions are responsible for 70% of the country's air pollution. Exhaust from vehicles has increased eight-fold over levels of twenty years ago. Air quality is worst in big cities like Kolkata, Delhi, Mumbai, Chennai, etc.

Air pollution can be defined as the mixing of harmful gases or chemical substances in the air, that results into harmful effects on flora as well as fauna. The major pollutants of air pollution includes the harmful untreated gases that are released into the atmosphere from factories, also the carbon monoxide gas released from the burnt fuel in the automobiles. Sometimes the leakage of radioactive substance also led to adverse effects on living organism.

Burning of fossil fuels leads to their combustion causing the release of carbon dies oxide in air. It also releases other harmful gases that cause air pollution. So, option B " Automobile exhausts and industrial wastes" is the correct answer.

The air around us has various types of unwanted suspended particles like- smoke, dust, pollens etc. When we inhale these particles get trapped in the hair present in our nasal cavity. However, sometimes these particles may get past the hair present in our nasal cavity. Then they irritate the lining of the cavity as a result of which we sneeze. Sneezing expels these foreign particles from the inhaled air and a dust-free, clean air enters our body. 

Air pollution is due to various substances that holds the potential to hinder the atmosphere or the well  being of the living beings surviving in it. The sustainment of all things living is due to a combination of gases  that collectively form the atmosphere; the imbalance caused by the increase or decrease of the percentage  of these gases can be harmful for survival. All the above mentioned a, b & c points are the cause of air  pollution.

The use of excessive chemical fertilizers and pesticides results in the water pollution and soil pollution. The construction of the housing estates results in air pollution. The quarrying of the limestone also results in the release of the particles causing air pollution. The increase in the forest reserves does not result in any kind of pollution. 

Lead is an important pollutant of soil and atmosphere. Lead is a heavy metal and very immobile element. Hence, the lead may quickly reach very high concentrations locally. Lead is a prominent pollutant released from factories manufacturing dry cells and batteries. In the atmosphere, lead is released by combustion of fossil fuels. Fossil fuels contain lead compounds as an additive as antiknock agents. Combustion of such fuel in vehicles leads to air pollution.

• Compressed natural gas (CNG) (methane stored at high pressure) is a fuel which can be used in place of gasoline, diesel fuel, and propane/LPG. CNG combustion produces fewer undesirable gases than gasoline.
• Hence In Delhi, CNG vehicles are used to control air pollution.
• So, the correct answer is 'CNG vehicles'.

Aerosols are the minute particles that are released with the pressure and remain suspended in the air. These can be sold particles or liquid droplets. The natural aerosols appear in the form of the fog, dust, forest exudates, geyser steams etc. The anthropogenic aerosols are more harmful and persist for the longer duration, like smoke, particulate matter etc. The emission from the jets comprises mainly of the fluorocarbons that are emitted with an immense pressure to provide propulsion to the engine.

Hydroelectric power is the cleanest form of electricity generation without contributing to the air pollution as it does not require the burning of fuel for working and water is provided by a natural force and moreover, it is renewable by rainfall causing refilling of reservoir. The dams are built which provide storage and it helps in reducing greenhouse gases emissions apart from the fact that once it becomes operative these have a low maintenance cost.

Electrostatic precipitators use the principle of electrically charging particles in an exhaust and then allowing them to settle on variably charged platforms. It is done primarily for control of SPM or suspended particulate matter such as dust, fumes, smoke etc.

H$ _2$S is a primary air pollutant emitted from putrifying substances, refineries, bituminous fuels etc. It causes burning sensation of throat and eyes along with feeling of vomiting or nausea. In plants it may cause defoliation and mottled chlorosis.

PM or particulate matter of diameter $2.5\,\,\mu$m or less is the most harmful as they are inhaled deep into the lungs causing serious lung damages, deposition in respiratory tracts and even death of the person.

There are several contaminants found in air. It is very important to purify this polluted air .A fine spray of water in a device known as scrubber can effectively separate many gases such as ammonia and sulphur dioxide.

The Air (Prevention and Control of Pollution) Act was enacted by the Parliament in 1981 for the control of air pollution and preservation of quality of air. This law has been enforced for sustaining the quality of environment.

Carbon dioxide is the greenhouse gas. It means that it traps the insolation from the sun and does not allow them to be reflected back. The trapped insolation work in warming the overall temperature of the earth. The level of atmospheric CO$ _{2}$ was around 200 ppm during the ice age. It rose to 280 ppm during the warmer interglacial periods. Presently, in the Anthropocene era, due to the excessive CO$ _{2}$ releasing activities like fossil fuel burning, the level of CO$ _{2}$ has risen to 360 ppm.

The increased and excessive use of automobiles and rapid growth of Industrial establishments post-industrial revolution era has contributed to the tremendous rise of pollution. The oxides of carbon, sulphur and nitrogen emission from vehicle exhaust and in the industrial process due to incomplete combustion of carbon compounds cause serious air pollution with other lethal gases release. The effluents from the industry that are toxic are released in the environment causing air pollution, noise pollution has become everyday routine with non-stop working of machinery and equipment, horns of car and engines harmful to people working around, establishments have caused deforestation leading to soil pollution.

The propellants used for jet engine release the halogenated paraffin compounds called fluorocarbons and chlorofluorocarbons. Both of these compounds are the potent ozone-depleting substances. Refineries, automobiles and industries release the oxides of carbon, sulphur and nitrogen.

The aircraft or jet planes engine emit certain particles and gases like carbon dioxide, hydrocarbons, nitrogen oxides, lead, black carbon, aerosols etc. These are basically greenhouse gases and anthropogenic compounds which have the tendency to react among themselves and with gases present in the atmosphere. Greenhouse effect, ozone depletion activities can be related to the emission of these gases. 

Knocking refers to the sensitivity shown by the fuel such as petrol. Due to this, petrol has low pressure and temperature of ignition and tends to ignite before the actual ignition spark in the air. This has deleterious effects on the engine and poses a great risk. To prevent this, the antiknocking agents like methyl tertiary butyl ether, toluene etc. are added to the fuel. These agents increase the temperature and pressure required for ignition.