Question

List the five primary air pollutants commonly released into the atmosphere and their sources.

Short answer

The five primary air pollutants are carbon monoxide, sulfur dioxide, nitrogen oxides, particulate matter, and volatile organic compounds.

Step-by-step solution

Identify Carbon Monoxide

Carbon monoxide (CO) is a primary air pollutant that originates from the incomplete combustion of carbon-containing fuels. It is commonly released by vehicles, especially those that use gasoline or diesel, and by coal-fired power stations.

Examine Sulfur Dioxide

Sulfur dioxide (SO2) is primarily emitted by power plants that burn fossil fuels like coal and oil. Other sources include industrial processes such as the extraction of metal from ore and the burning of high-sulfur containing fuels in industries.

Discuss Nitrogen Oxides

Nitrogen oxides (NOx), which include both nitrogen dioxide (NO2) and nitric oxide (NO), are released from vehicle engines and power plants. These gases are the result of high-temperature combustion processes.

Explain Particulate Matter

Particulate matter (PM) consists of tiny particles suspended in the air, such as dust, soot, and smoke. Common sources include construction sites, unpaved roads, fields, smokestacks, and fires.

Understand Volatile Organic Compounds

Volatile Organic Compounds (VOCs) are emitted from a variety of sources, including vehicle exhaust, industrial processes, household products, and the evaporation of gasoline and solvents.

Key concepts

Carbon Monoxide

Carbon monoxide, or CO, is a colorless, odorless gas that can be quite harmful to human health. It forms when carbon-containing fuels do not burn completely. This is a common occurrence in places where fossil fuels are extensively used. For example:

• Vehicle emissions: Cars, trucks, and other motor vehicles largely contribute to CO emission, especially when idling.
• Industrial sources: Factories, especially those that use industrial ovens or heaters powered by fossil fuels, also release a significant amount of carbon monoxide.
• Residential sources: In homes, poorly maintained furnaces and stoves can be sources of CO.

Exposure to high levels of carbon monoxide can lead to severe health problems, such as headaches, dizziness, and even poisoning.

Sulfur Dioxide

Sulfur dioxide (SO2) is another major air pollutant, characterized by its sharp, pungent smell. It's primarily released during the combustion of fossil fuels that contain sulfur. This is most commonly associated with power plants and industrial processes. Here's where SO2 comes from:

• Power plants: Burning coal or oil in power generation produces large amounts of sulfur dioxide.
• Industrial processes: Actions like smelting metals emit SO2 into the atmosphere.
• Volcanic activity: Naturally occurring sulfur dioxide is released during volcanic eruptions.

Once in the atmosphere, sulfur dioxide can transform into sulfuric acid, contributing to acid rain, which damages environments and buildings.

Nitrogen Oxides

Nitrogen oxides, collectively known as NOx, are a group of gases primarily comprising nitrogen dioxide (NO2) and nitric oxide (NO). These gases are produced during high-temperature combustion processes, especially when there is a mix of air and fuel. Key sources include:

• Vehicle engines: Cars and trucks are significant sources due to the combustion of fuel at high temperatures.
• Power plants: Facilities using coal or natural gas for electricity generation also contribute to NOx production.
• Industrial facilities: Manufacturing plants that involve combustion can produce nitrogen oxides.

On reacting with other atmospheric gases, NOx can form harmful compounds like ozone, adversely affecting respiratory health and contributing to smog formation.

Particulate Matter

Particulate matter (PM) includes tiny particles or droplets in the air that are smaller than 10 micrometers. They are categorized as PM10 or PM2.5 based on size. These particles originate from various sources:

• Construction sites: Dust and debris from building activities contribute to particulate matter levels.
• Unpaved roads: Vehicles stir up dust that adds to atmospheric PM.
• Wildfires and burning: Smoke from fires releases a mix of particulates.
• Industrial processes: Factories and power plants emit particulates through smokestacks.

Particulate matter can penetrate deep into the lungs and even enter the bloodstream, posing severe health risks for humans, such as respiratory and cardiovascular issues.

Volatile Organic Compounds

Volatile Organic Compounds (VOCs) are a large group of organic chemicals that can evaporate easily into the air. Many products people use every day release VOCs, contributing to air pollution. Their sources include:

• Vehicle exhaust: Cars and other engines emit VOCs when burning fuel.
• Household products: Paints, varnishes, and cleaning supplies can release VOCs.
• Industrial facilities: Production processes often emit these volatile compounds.
• Natural sources: Some plants naturally emit VOCs.

In the presence of sunlight, VOCs can react with nitrogen oxides to form ozone, a harmful pollutant that contributes to urban smog and has various health impacts.