Which of the following is not applicable to secondary air pollutants?

Correct option is D

The correct answer is (d) They are non-hazardous air pollutants. Secondary air pollutants are, in fact, hazardous and can have serious health and environmental impacts.
Understanding Secondary Air Pollutants:
1. Primary Pollutants:
· Directly emitted from sources like vehicles, factories, and power plants. Examples include SO₂, NOₓ, CO, and VOCs.
2. Secondary Pollutants:
· Formed when primary pollutants undergo chemical or physical transformations in the atmosphere. Examples include:
· Ozone (O₃)
· Sulfuric acid (H₂SO₄)
· Nitric acid (HNO₃)
· Particulate matter (PM) from chemical reactions.
Why Options (a), (b), and (c) Are Correct:
1. (a) They are important with respect to human health:
· Secondary pollutants like ozone and particulate matter can cause respiratory issues, cardiovascular diseases, and other health problems.
2. (b) They have undergone chemical/physical transformation in air:
· Secondary pollutants form through reactions involving primary pollutants. For example, ozone is produced by the reaction of NOₓ and VOCs under sunlight.
3. (c) They include both inorganic and organic species/compounds:
· Secondary pollutants can be inorganic (e.g., sulfuric acid) or organic (e.g., secondary organic aerosols).
Why Option (d) Is Incorrect:
· (d) They are non-hazardous air pollutants:
· This statement is not applicable because secondary air pollutants are hazardous and pose significant health and environmental risks.
Information Booster 1. Examples of Secondary Pollutants:
· Ozone (O₃): Causes respiratory problems and damages vegetation.
· Acid Rain: Formed from sulfuric and nitric acids.
· Photochemical Smog: Formed by reactions involving NOₓ and VOCs.
2. Formation Process:
· Secondary pollutants form in the atmosphere through processes like oxidation, photochemical reactions, and condensation.
3. Health Effects:
· Secondary pollutants contribute to asthma, lung damage, and heart diseases.
4. Regulation:
· Monitored and regulated under the National Ambient Air Quality Standards (NAAQS).
Additional Knowledge · Primary vs. Secondary Pollutants:
· Primary: Directly emitted (e.g., CO, SO₂).
· Secondary: Formed in the atmosphere (e.g., O₃, PM₂.₅).
· Mitigation:
· Reducing primary emissions helps control secondary pollutants. For instance, reducing NOₓ and VOC emissions helps decrease ozone levels.