In News:

A first-of-its-kind comprehensive study has detected inhalable microplastics in the ambient air of major Indian cities, uncovering a largely ignored dimension of urban air pollution. The research monitored air samples from densely populated market areas across Delhi, Mumbai, Kolkata, and Chennai, highlighting a regulatory blind spot in current air quality assessment systems.

What are Inhalable Microplastics?

• Definition: Tiny airborne plastic particles smaller than 10 micrometres (µm) that can remain suspended in air and be inhaled deep into the lungs.
• Unlike larger microplastics that settle quickly, these particles persist in the atmosphere due to low gravitational settling velocity.
• They are now emerging as airborne contaminants, alongside conventional pollutants such as PM?.? and PM??, sulphur dioxide (SO?), nitrogen dioxide (NO?), carbon monoxide (CO), ozone (O?), lead (Pb), and ammonia (NH?).

Sources of Inhalable Microplastics

• Tyre and brake wear from road transport
• Synthetic clothing fibres (polyester, nylon)
• Plastic packaging and urban waste mismanagement
• Paints, cosmetics, and open waste burning

Key Findings of the Study

• New Air Pollutant Identified: Inhalable microplastics are not adequately captured by existing Air Quality Index (AQI) frameworks.
• City-wise Variation: Levels were significantly higher in Delhi and Kolkata compared to Mumbai and Chennai, attributed to:
  • Coastal dispersion of pollutants in Mumbai and Chennai
  • Higher population density and poorer waste management in Delhi and Kolkata
• High Human Exposure: Urban residents inhale approximately 132 micrograms (µg) of microplastics daily, indicating chronic exposure at breathing height.
• Carrier of Toxins: These particles act as “Trojan horses,” transporting:
  • Heavy metals (lead, cadmium)
  • Endocrine-disrupting chemicals (phthalates)
• Health Risks:
  • Deep lung penetration leading to respiratory disorders
  • Increased risk of hormonal imbalance, cancer, and long-term lung damage
  • Ability to carry microbes such as Aspergillus fumigatus, including antibiotic-resistance genes, raising concerns over drug-resistant respiratory infections

Microplastics: Background

• Definition: Plastic particles <5 mm in size; particles <100 nanometres are termed nanoplastics.
• Formation: Fragmentation of larger plastics due to UV radiation, heat, wind, waves, and mechanical abrasion.
• Types:
  • Primary microplastics: Intentionally manufactured (microbeads in cosmetics, plastic pellets, synthetic fibres).
  • Secondary microplastics: Formed from degradation of larger plastic items (bags, bottles, packaging, fishing nets).

Major Sources

• Synthetic textiles
• Road transport (tyre wear)
• Single-use plastics
• Personal care products
• Ineffective plastic waste management

Regulatory Measures in India

• Ban on single-use plastics
• India Plastics Pact
• Plastic Waste Management (Amendment) Rules, 2024