3.1. Major Pollutants from Combustion

The biggest contributor to air pollution is ‘combustion.’ This is the primary activity where emissions are released into the air.

Combustion refers to the process of burning fuel to produce energy. This process releases various gases and particulates into the atmosphere, significantly impacting air quality. It's essential to understand that combustion happens in many sources, such as vehicles, power plants, and industrial processes, leading to diverse pollutants.

You can think of combustion like cooking on a stove. When you cook using gas, the flame burns the fuel, producing heat for cooking. However, this process also releases smoke and gases. Similarly, large-scale combustion releases pollutants that are harmful to the environment.

From combustion, some major pollutants include NOx, SO2, ozone, particulate matter, and carbon monoxide.

This chunk lists significant pollutants emitted during combustion. NOx (nitrogen oxides) and SO2 (sulfur dioxide) are particularly harmful gases that contribute to acid rain and respiratory problems. Ozone forms at ground level due to chemical reactions involving these gases and sunlight. Particulate matter consists of tiny solid or liquid particles that can penetrate lungs and cause health issues. Carbon monoxide is a colorless, odorless gas that can be fatal in high concentrations.

Imagine a busy urban street with cars constantly emitting exhaust fumes. The nitrogen oxides and sulfur dioxide from these vehicles contribute to smog, which can be harmful to our health, similar to how inhaling smoke from a fire can cause coughing and difficulty breathing.

Lead used to be a significant pollutant from petrol (gasoline) as an anti-knocking agent. However, lead has been phased out, reducing its concentration in the atmosphere.

Leaded petrol was commonly used to improve engine performance. However, lead is toxic and can cause severe health problems, including neurological damage. Due to regulations, leaded petrol has been largely banned, resulting in a decrease in lead emissions from vehicles.

Consider using a bicycle instead of driving a car. When riding a bike, you contribute less to air pollution because you’re not burning fuel, just like the phase-out of leaded petrol reduces the harmful lead emissions from cars.

Unburnt hydrocarbons are also a concern. They occur when combustion is not complete, resulting in fuel vapor that can enter the atmosphere.

Unburned hydrocarbons represent fuel that has not completely combusted during the process. This can happen due to improper fuel-air mixtures or malfunctioning engines. These hydrocarbons can persist in the air, contributing to the formation of ground-level ozone and smog.

Think of trying to ignite a campfire. If you don’t have enough kindling (like dry leaves) or the right airflow, the fire won't catch fully, and you’ll see smoke and unburned material instead of clean flames. Similarly, poorly functioning vehicles can release unburned hydrocarbons into the air.

Additionally, fuel additives like benzene, toluene, ethyl benzene, and xylene (collectively known as BTEX) are present in emissions.

BTEX compounds are organic chemicals commonly found in fuels. While they help improve fuel properties, they are also known to be harmful pollutants that can pose significant risks to health and the environment, including respiratory illness and environmental contamination.

Imagine if you spilled paint while working on a home improvement project. The strong fumes from the paint can make you feel dizzy and ill, similar to how exposure to BTEX compounds from vehicle emissions can negatively impact our health.

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