Question

Which of the following is not an air pollutant? (a) \(\mathrm{N}_{2} \mathrm{O}\) (b) \(\mathrm{N}_{2}\) (c) \(\mathrm{CO}\) (d) \(\mathrm{NO}\)

Short answer

(b) \( \mathrm{N}_2 \) is not an air pollutant.

Step-by-step solution

Identify Pollutants

First, recognize that air pollutants are substances in the air that can have harmful effects on the environment or human health. Common examples include gases such as carbon monoxide (\( \mathrm{CO} \)), nitrogen oxides (\( \mathrm{NO}_x \)), and nitrous oxide (\( \mathrm{N}_2 \mathrm{O} \)).

Evaluate Each Substance

Review each option to determine if it is recognized as an air pollutant:- (a) \( \mathrm{N}_2 \mathrm{O} \) (Nitrous Oxide) is a known greenhouse gas and air pollutant.- (b) \( \mathrm{N}_2 \) (Nitrogen) is a major component of Earth's atmosphere and is not considered a pollutant.- (c) \( \mathrm{CO} \) (Carbon Monoxide) is a harmful air pollutant.- (d) \( \mathrm{NO} \) (Nitric Oxide) is part of the nitrogen oxides, which are common pollutants.

Determine the Non-Pollutant

The only substance in the list that is a naturally abundant component of clean air and is not an air pollutant is \( \mathrm{N}_2 \). Therefore, the correct answer is (b) \( \mathrm{N}_2 \).

Key concepts

Nitric Oxide

Nitric oxide (NO) is one of the nitrogen oxides commonly found as pollutants in the air. It's a colorless gas that forms mainly from the combustion processes, such as those in car engines and power plants. When fuels are burned at high temperatures, nitrogen and oxygen in the air react to form NO. Once in the atmosphere, NO can further react with oxygen to form nitrogen dioxide (NO₂).
NO₂, along with other nitrogen oxides, contribute to the formation of smog and acid rain, both of which have harmful effects on living organisms and the environment. Smog can impair breathing and exacerbate conditions like asthma, while acid rain can damage ecosystems and structures.

• NO contributes to the formation of ground-level ozone, a key component of smog.
• It can cause respiratory issues and affects lung function.
• Efforts to reduce NO emissions focus on improving combustion efficiency and using catalytic converters in vehicles.

Carbon Monoxide

Carbon monoxide (CO) is a potentially lethal air pollutant that is colorless, odorless, and tasteless. It results from the incomplete burning of carbon-based fuels, such as gasoline, wood, and coal. This can occur in poorly ventilated spaces, engines, and fires.
When inhaled, CO interferes with the blood's ability to carry oxygen, leading to serious health effects. High exposures can cause unconsciousness or even be fatal, while long-term exposure can lead to heart disease.

• CO binds with hemoglobin in the blood more effectively than oxygen, reducing the amount of oxygen that can be transported throughout the body.
• It's crucial to ensure proper ventilation and functioning detectors in homes and vehicles to prevent CO buildup.
• Mitigation strategies include the use of catalytic converters and ensuring appliances are well-maintained and vented properly.

Greenhouse Gases

Greenhouse gases (GHGs) are atmospheric gases that trap heat from the sun and keep the planet warm, a natural process known as the greenhouse effect. However, increased levels of these gases due to human activities have led to global warming and climate change.
Examples of common GHGs include carbon dioxide (\( \mathrm{CO}_2 \)), methane (\( \mathrm{CH}_4 \)), and nitrous oxide (\( \mathrm{N}_2 \mathrm{O} \)). These gases are emitted from various sources, such as burning fossil fuels, deforestation, and agriculture.

• Greenhouse gases contribute to the warming of Earth's atmosphere, leading to climate changes like more extreme weather events.
• Efforts to reduce GHG emissions involve transitioning to renewable energy sources and enhancing energy efficiency.
• Reducing emissions also involves changing agricultural practices and implementing policies to protect forests.