ONE-THIRD OF DELHI’S PM2.5 POLLUTION IS SECONDARY AMMONIUM SULFATE: CREA ANALYSIS

NEWS  – A new analysis by the Centre for Research on Energy and Clean Air (CREA) finds that nearly one-third of Delhi’s annual PM2.5 pollution comes from secondary ammonium sulfate, formed through atmospheric chemical reactions driven largely by SO₂ emissions from coal plants, industries, and ammonia from agriculture.

KEY FINDINGS

• Secondary ammonium sulfate forms when:
  • SO₂ → sulfate → reacts with ammonia → ammonium sulfate
• Shares of ammonium sulfate in Delhi PM2.5:
  • 49% in post-monsoon
  • 41% in winter
  • 21% in summer/monsoon
• India: World’s largest SO₂ emitter (~11.2 million tonnes)
• Severe pollution episodes are region-driven, not only local

MAJOR STATES WITH HIGH SECONDARY PM2.5

• Chhattisgarh – 42%
• Odisha – 41%
• Jharkhand, Telangana – 40%
• Bihar – 39%
• Maharashtra, AP, West Bengal – 38%
• Uttar Pradesh, MP – 37%

KEY ISSUES TO PONDER

Sources of Ammonium Sulfate

• Coal power plants (SO₂)
• Industries
• Agriculture (ammonia emissions)
• Atmospheric humidity accelerates formation

Impact on Health

• PM2.5 penetrates lungs → bloodstream
• Causes:
  • Asthma, bronchitis
  • Heart disease
  • Respiratory disorders
• SO₂ exposure:
  • Cardiovascular risk
  • Respiratory illness
  • Damages vegetation

Measuring Air Pollution

• PM2.5 concentration (µg/m³)
• Air Quality Index (AQI)
• Satellite emission tracking

Why PM2.5 is Dangerous

• Tiny size → bypass nose & throat
• Remains suspended in air
• Long-term chronic exposure risk

STEPS NEEDED TO CURB SO₂ EMISSIONS

• Strict enforcement of Flue Gas Desulphurisation (FGD) in power plants
• Transition to cleaner fuels
• Agricultural ammonia management
• Industrial emission standards
• Regional coordination (since pollution is transboundary)

MAJOR CAUSES OF AIR POLLUTION IN INDIA

• Thermal power plants
• Industrial emissions
• Vehicular pollution
• Biomass burning
• Construction dust
• Agricultural burning
• Secondary particulate formation (chemically formed)

DO YOU KNOW

• PM2.5 = particles <2.5 microns
• Enter bloodstream → systemic health risk
• India records up to 42% PM2.5 as secondary chemical formation