7.1.1. AIR POLLUTION

Air pollution may be described as “the imbalance in quality of air so as to cause adverse effects on the living organisms existing on earth.” Pollution is due to the presence of undesirable substances of sufficient quantity which exist in the environment. The substance or energy which causes pollution is called pollutant.

Air pollution refers to when the quality of air is disrupted or adversely affected due to harmful substances being present. These harmful substances, known as pollutants, can be found in the air in significant amounts, enough to pose health risks to living organisms, including humans. Essentially, when air contains too many undesired particles, gases, or pollutants, it becomes unsafe to breathe.

Think of the air as a glass of clean water. If you add dirt or sugar into the glass, the water no longer remains clean and drinkable. Similarly, when pollutants are added to the air, its quality deteriorates, becoming harmful to those who breathe it.

Pollutants may be classified according to origin and state of matter.

a) According to Origin: Air pollutants are divided into two categories as primary & secondary.

1. Primary air pollutants are those which are emitted directly into the atmosphere. Eg: C; CO; CO; SOx; N; S; H; NOx; CFC’s etc.
2. Secondary air pollutants are those which are produced in the air by the interaction among the primary air pollutants or by reaction with atmospheric constituents. Eg: Ozone (O3); Smog; Para Acetyl Nitrate (PAN); Acid Rain; Aerosols.

b) According to State of Matter: Air pollutants include fine solids; liquids and gases. Dust, Smoke, Fumes etc are examples for solid particles whereas fog is an example for liquid particles.

Air pollutants can be categorized based on their origin or the state they exist in. Primary pollutants are released directly into the air, like carbon monoxide from cars. Secondary pollutants are formed when primary pollutants interact with other substances in the atmosphere, such as ozone, which forms when sunlight interacts with emissions. Additionally, pollutants can be in solid, liquid, or gas forms, like dust (solid), fog (liquid), or smoke (gas). This classification helps to understand the sources and behaviors of these pollutants.

Picture cooking with a gas stove. The smoke emitted from burning food is a primary pollutant, directly released into the air. Now, if that smoke combines with water vapor in the air to create a smog, that smog represents a secondary pollutant formed from the initial cooking smoke.

1. Carbon Monoxide: It is a colorless, odorless, poisonous gas produced by the incomplete burning of carbon-based fuels (coal, petrol, diesel, and wood). About 70% of CO emissions come from the transport sector. It can deprive human blood of oxygen, potentially leading to coma and death. In mild dosages, it causes headaches.
2. Oxides of Sulphur: SO2 is produced from burning coal, mainly in thermal power plants and some industries. It harms human health and the environment, contributing to smog and acid rain.
3. Oxides of Nitrogen: NOx compounds are produced from burning fossil fuels and can cause respiratory issues and contribute to forming ozone.
4. Chloro Fluoro Carbons: CFCs are non-toxic chemicals that used to be common in refrigeration and now contribute to ozone layer depletion.

Primary air pollutants are directly emitted into the atmosphere and have various forms and sources. Carbon monoxide is toxic and is a product of incomplete combustion. Sulfur dioxide is associated with burning fossil fuels and can lead to severe environmental problems like acid rain. Nitrogen oxides, also from combustion, can affect lung health. Lastly, chlorofluorocarbons, which were extensively used in refrigeration, damage the ozone layer, making us more vulnerable to harmful UV rays.

Imagine driving a car with a faulty exhaust that emits carbon monoxide. This gas is invisible and odorless, but it can poison someone inside the closed car. Just like the invisible danger of CO, pollutants can be lurking in the air around us, having harmful long-term effects.

1. Ozone (O3): Produced in the atmosphere, ozone is beneficial in the stratosphere but harmful at ground level, causing respiratory issues.
2. Smog: A mix of smoke and fog, causing health problems such as respiratory diseases.
3. Acid Rain: Formed when SOx and NOx react in the atmosphere, causing detrimental effects on soil, water, and structures.

Secondary pollutants form in the atmosphere from chemical reactions between primary pollutants and other atmospheric components. Ozone, while protecting us from UV rays high in the atmosphere, becomes a health hazard at ground level where it can cause breathing problems. Smog combines smoke and fog, creating visibility issues and health risks. Acid rain occurs when pollutants like sulfur dioxide and nitrogen oxides combine with water vapor, falling to the ground and harming ecosystems.

Think of baking a cake. You mix different ingredients to create your final product, just as different primary pollutants mix in the atmosphere to form secondary pollutants. For example, a thick layer of smog in a city can often be like an overcooked cake—a result of too many elements combined in the wrong conditions.

Air pollution causes deaths, impairs health, reduces visibility, and results in vast economic losses. It can also lead to intangible losses, such as damage to historical monuments. The atmosphere, primarily the troposphere, contains essential gases that support life.

The harmful impacts of air pollution stretch across health, visibility, economy, and heritage. Polluted air can lead to serious health issues, including respiratory diseases and premature death. It hampers visibility, causing accidents, and creates economic burdens due to healthcare costs and lost worker productivity. Additionally, air pollution can harm cultural sites and monuments, leading to further losses.

When wildfires occur, the smoke impacts the air quality, leading to health alerts. This situation can drown out visibility on roads and result in hospitalizations, showcasing how air pollution directly affects our day-to-day lives, akin to a ripple effect that touches many aspects of existence.

Methods to reduce air pollution include:

• Using inputs that do not contain pollutants;
• Modifying operations to minimize pollution generation;
• Replacing processes to eliminate pollutants;
• Removing pollutants from processes;
• Substituting raw materials;
• Involving control technologies like scrubbers and electrostatic precipitators.

Preventing and controlling air pollution involves proactive measures and technological solutions. This includes using cleaner inputs that don't introduce pollutants, adjusting production processes to lower emissions, adopting raw materials with lower environmental impacts, and cleaning up emissions before they are released into the air through equipment like scrubbers or filters. These steps can be crucial in maintaining air quality.

Imagine a factory that realizes its waste is polluting nearby rivers. By changing its production process to use water instead of harmful chemicals, it prevents pollution from occurring, much like cleaning up a messy room before guests arrive. Consistent maintenance and proactive practices keep both the room – or the environment – in good condition.

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