Inhalable Microplastics

Inhalable Microplastics have become the invisible threat in urban air pollution, according to a study. The threat shines light on the blind spot in India’s air quality regulations. Read here to learn more.

A first-of-its-kind comprehensive study published in Environment International has detected inhalable microplastics in the ambient air of major Indian cities, revealing a critical yet overlooked dimension of urban air pollution.

The study monitored air quality across densely populated market areas in Delhi, Mumbai, Kolkata, and Chennai, exposing a regulatory blind spot in India’s existing Air Quality Index (AQI) framework.

What are Inhalable Microplastics?

• Inhalable microplastics are airborne plastic particles smaller than 10 micrometres (µm) that can remain suspended in the atmosphere for prolonged periods.
• Unlike larger microplastics that settle quickly, these particles can be inhaled deep into the lungs, similar to PM₂.₅.
• They are now emerging as a new class of air pollutants, alongside conventional pollutants like PM2.5, PM10, SO₂, NO₂, CO, O₃, Pb, and NH₃.

Major Sources

• Synthetic textile fibres (polyester, nylon)
• Tyre and brake wear from vehicles
• Plastic packaging degradation
• Paints, cosmetics, and urban dust
• Open waste burning and poor plastic waste management

Key Findings of the Study

1. Emergence of a New Urban Air Pollutant

• The study establishes inhalable microplastics as a significant but unregulated component of urban air pollution.
• Existing AQI frameworks do not measure or report microplastic concentrations, creating a regulatory and monitoring gap.

2. High Atmospheric Persistence

• Due to low gravitational settling velocity, inhalable microplastics remain airborne for long durations.
• This increases the likelihood of chronic inhalation exposure, especially in high-density urban settings.

3. City-wise Variation

• Delhi and Kolkata recorded significantly higher concentrations than Mumbai and Chennai. Contributing factors include:

• • Higher population density and traffic load
  • Poor waste segregation and disposal
  • Lack of coastal winds that aid pollutant dispersion (as in Mumbai and Chennai)

4. Significant Daily Human Exposure

• Urban residents are estimated to inhale around 132 micrograms of microplastics daily.
• Exposure occurs at breathing height, making it a continuous and unavoidable risk in city environments.

5. Dominant Sources of Exposure

• Tyre wear particles
• Plastic packaging fragments
• Urban dust and waste mismanagement
• Every day, human activities in congested public spaces

Health Implications of inhalable microplastics

1. Deep Lung Penetration: Due to their microscopic size, inhalable microplastics can reach the alveolar regions of the lungs, potentially crossing biological barriers.
2. “Trojan Horse” Effect: These particles adsorb and transport toxic co-pollutants, including:

• • Heavy metals such as lead and cadmium
  • Endocrine-disrupting chemicals like phthalates
• This amplifies the risks of respiratory diseases, hormonal disorders, immune dysfunction, and cancers.

3. Microbial and Antibiotic Resistance Risks

• The study detected microbes such as Aspergillus fumigatus attached to microplastic particles.
• Presence of antibiotic-resistance genes raises concerns about drug-resistant respiratory infections, especially in immunocompromised populations.

Significance for India

• India already bears a high burden of air pollution-related morbidity and mortality.
• The discovery of inhalable microplastics suggests that current air quality assessments underestimate actual health risks.
• Vulnerable groups, children, the elderly, outdoor workers, and urban poor face disproportionately higher exposure.

Policy and Governance Gaps

• Absence of microplastics in AQI standards and National Ambient Air Quality Standards (NAAQS).
• Limited interdisciplinary coordination between the environment, health, urban development, and waste management authorities.
• Inadequate regulation of plastic production, tyre composition, and synthetic textiles.

Way Forward

1. Regulatory Integration

• Recognise inhalable microplastics as an air pollutant under national air quality frameworks.
• Develop standardised monitoring and reporting protocols.

2. Source Reduction

• Promote low-wear tyre technologies and sustainable textiles.
• Strengthen plastic waste management and curb open burning.

3. Health Surveillance

• Integrate microplastic exposure into urban health risk assessments.
• Support long-term epidemiological studies.

4. Urban Planning and Awareness

• Improve ventilation corridors and green buffers in cities.
• Raise public awareness about invisible air pollutants beyond PM₂.₅.

Conclusion

The detection of inhalable microplastics in Indian cities exposes a hidden layer of air pollution with profound health implications.

It challenges conventional pollution metrics and calls for an urgent rethinking of air quality governance. Addressing this emerging threat requires scientific integration, regulatory innovation, and preventive urban planning to safeguard public health in rapidly urbanising India.

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Frequently Asked Questions (FAQs)

Q. What are inhalable microplastics?

Inhalable microplastics are airborne plastic particles smaller than 10 micrometres (µm) that can remain suspended in the atmosphere and be inhaled deep into the lungs, similar to PM2.5 particles.

Q. How are inhalable microplastics different from conventional microplastics?

Conventional microplastics are usually found in water, soil, and food and tend to settle due to gravity. In contrast, inhalable microplastics have low settling velocity, stay airborne longer, and pose direct respiratory exposure risks.

Q. Why are inhalable microplastics called “Trojan horse” pollutants?

They carry toxic chemicals and microbes on their surface, enhancing the toxicity of other pollutants and enabling them to enter the human body through inhalation.