On the basis of source

Primary Pollutants

• directly released into the environment
• in original state
  • cause pollution in original state
• Example:
  • CO₂
  • plastic
  • SO₂

Secondary Pollutants

• first, react with 1° pollutant ➡️ pollute the environment
• Example:
  • PAN (peroxyl acetyl nitrate)
  • SO₃
  • methyl Hg