Question

What is a secondary pollutant?

Answer 1

Pollutant:

• The harmful and undesirable substances mixed in the air are called pollutants.
• Air gets polluted by smoke, dust, and coke emitted by running automobiles and chimneys of industries.
• Some common air pollutants are gases like sulphur dioxide (${\mathrm{SO}}_2$), carbon monoxide ($\mathrm{CO}$), and nitrogen oxides (${\mathrm{NO}}_2$).

Primary pollutant:

• A primary pollutant is an air pollutant emitted from a source directly into the atmosphere.
• The source can be either a natural process such as sandstorms and volcanic eruptions or anthropogenic (influenced by humans) such as industrial and vehicle emissions.
• Examples of primary pollutants are sulphur dioxide (${\mathrm{SO}}_2$), carbon monoxide ($\mathrm{CO}$), nitrogen oxides (${\mathrm{NO}}_2$), and particulate matter.

Secondary pollutant:

• Secondary pollutants are pollutants that form in the atmosphere.
• These pollutants are not emitted directly from a source (like vehicles or power plants), Instead, they form as a result of the pollutants emitted from these sources reacting with molecules in the atmosphere to form a new pollutant.
• Examples of secondary pollutants are ozone, organic aerosol, Peroxyacyl Nitrate (PAN), etc.