Inhalable Microplastics and Urban Air Pollution

Why is this in News?

• November–December 2025:
  • A first-of-its-kind Indian study, published in Environment International, has flagged inhalable microplastics as a serious and overlooked air pollutant.
  • Conducted across Delhi, Mumbai, Kolkata, and Chennai by IISER Kolkata.
• Context:
  • Severe winter smog episodes in NCR.
  • Public protests demanding the right to clean air.
• Key finding:
  • City residents inhale ~132 micrograms of microplastics daily, with Delhi and Kolkata worst affected.

Relevance

GS III – Environment & Public Health

• Emerging environmental contaminants.
• Limitations of AQI and existing pollution frameworks.
• Urban air pollution and health externalities.
• Plastic waste management failures.

What are Microplastics?

• Microplastics:
  • Plastic particles <5 mm in size.
• Inhalable microplastics:
  • Particles <10 micrometres (µm).
  • Small enough to:
    • Bypass nasal filtration.
    • Penetrate deep lung tissue.
• Source:
  • Primary: Microbeads, synthetic fibres.
  • Secondary: Breakdown of larger plastic waste.

Traditional Air Pollution Framework

• Focus on criteria pollutants:
  • PM2.5, PM10.
  • SO₂, NOx, CO, ozone, lead.
• AQI:
  • Does not explicitly account for microplastics.
• Gap:
  • Emerging contaminants like microplastics remain outside regulatory radar.

Key Findings of the Study

Concentration Levels

• Average inhalable microplastics (4 cities):
  • 8.8 µg/m³.
• Daily exposure:
  • ~132 µg per person per day.
• City-wise exposure:
  • Delhi: 14.18 µg/m³
  • Kolkata: 14.23 µg/m³
  • Mumbai: 2.65 µg/m³
  • Chennai: 4 µg/m³

Seasonal Variation

• Winter evenings:
  • 32.7 particles/m³
• Non-winter evenings:
  • 18.8 particles/m³
• 74% increase during winter due to:
  • Temperature inversion.
  • Low wind speed.
  • Poor dispersion.

“Trojan Horse” Effect

• Microplastics act as carriers for:
  • Heavy metals:
    • Lead (highest in Kolkata).
    • Cadmium.
  • Endocrine-disrupting chemicals:
    • Diethyl phthalates.
  • Microbes:
    • Fungi like Aspergillus fumigatus.
    • Antibiotic-resistance genes.
• Net impact:
  • Amplifies toxicity beyond physical particles.

Health Implications

• Deep lung penetration → chronic exposure.
• Linked risks:
  • Respiratory diseases.
  • Hormone-related disorders.
  • Cancer.
  • Breast and reproductive health issues.
• High-risk groups:
  • Traffic police.
  • Construction workers.
  • Urban informal labour.
• Tyre-wear microplastics:
  • Identified as particularly carcinogenic.

Sources of Inhalable Microplastics

• Urban origins:
  • Tyre wear.
  • Synthetic textiles.
  • Packaging materials.
  • Cosmetics.
  • Construction activities.
  • Household waste.
• Waste management failures:
  • Open dumping.
  • Burning of plastics.
  • Poor segregation.

Why Delhi and Kolkata are Worse Affected

• High population density.
• Severe waste mismanagement.
• Landlocked geography.
• Adverse winter meteorology.
• Contrast:
  • Mumbai and Chennai benefit from:
    • Coastal winds.
    • Better atmospheric dispersion.

Governance and Policy Gaps

• AQI framework:
  • Not designed to capture microplastics.
• Plastic regulation:
  • Weak enforcement of single-use plastic bans.
• Occupational safety:
  • No specific standards for microplastic exposure.
• Waste management:
  • Persistent urban governance failures.

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