Another winter has come, and with it comes the familiar ritual: a smoky haze, stinging throat, and an air quality index that dips sharply as the temperature falls. We blame vehicle emissions, construction dust, factory smoke, crop burning, and stagnant cold air that traps pollutants to the ground.
But what if the threat floating in this winter air is something we cannot see? What if every breath carries not just dust and smoke, but plastic?
A groundbreaking study led by the researchers of the Indian Institute of Science Education and Research, Kolkata, IMSc Chennai, and AIIMS, Kalyani has revealed a new component of urban air pollution: Inhalable Microplastics (iMPs). These particles,smaller than 10 micrometers, are so pervasive that they are now challenging our traditional understanding of what makes the air toxic.
The multidisciplinary study titled, ‘The Dawn of a New Air Pollutant: Inhalable Microplastics as Emerging Vectors of Hazardous Contaminants and Their Implications for Human Health’, was recently published in the journal ‘Environment International’. It is the first study in India to measure microplastics directly at human breathing height across the crowded market of four major metro cities: Delhi, Kolkata, Mumbai, and Chennai.
Using technology like Pyrolysis-Gas Chromatography/ Mass Spectrometry, the researchers quantified the plastic content in the air. The findings are alarming: Kolkata topped the list with the highest average concentration of iMPs at 14.23 µg per cubic meter of air. Delhi followed closely at 14.18 µg/m³. Even the coastal cities recorded significant levels, with Chennai at 4 µg/m³ and Mumbai at 2.65 µg/m³. Researchers estimate that an average urban resident inhales 2.9 grams of microplastics in their lifetime, which is equivalent to breathing in a small plastic bottle.
For years, PM 10 and PM 2.5, tiny particles from dust, smoke, and fuels, have been the primary concerns in the discussions on air pollution. However, the new study reveals that microplastics now account for up to 5 per cent of the total of PM 10 and PM 2.5 in India’s metropolitan markets. Their sources are rooted in daily life: polyester from clothing, packaging materials, and rubber from vehicle tires and footwear.
Unlike natural dust, plastic particles are aerodynamic and lightweight. They do not settle easily or wash away. They remain suspended for extended periods, allowing them to travel across cities and countries. Once inhaled, their small size allows them to penetrate deep into the lungs, cross the delicate tissue barriers, enter the bloodstream, and potentially reach vital organs.
But the concern doesn’t stop with the plastic itself. The study further reveals that these airborne microplastics act as ‘Trojan horses’, picking up and transporting a range of harmful substances. It provides the first empirical evidence globally that airborne microplastics can carry pathogens. Using high-throughput sequencing, the team identified bacteria and fungi attached to these particles, including Aspergillus fumigatus and Candida (a known respiratory pathogen), and several Bacillus species carrying antibiotic resistance and virulence factor genes. “We have found that these plastics can act as vectors to transport pathogens that may affect the immune system. These plastics can be potential carriers of infection. This amplifies the risk of disease transmission in densely populated urban environments,” Prof. Gopala Krishna Darbha, corresponding author of the study, said in a conversation with The Statesman.
Beyond pathogens, the microplastics were found to be loaded with toxic chemical additives. The team detected diethyl phthalate (DEP), a common plasticiser and fragrance stabiliser, linked to endocrine disruption, reproductive toxicity, and respiratory irritation. Delhi, Kolkata, and Mumbai showed the highest atmospheric concentrations of DEP, which can enter the air from cosmetics, plastics, packaging, and PVC products.
Kolkata and Delhi also registered high levels of lead, which exceed the national safety limits. Often used as a stabiliser and pigment in PVC, tyres, and coatings, lead in the air poses severe health risks, particularly to children, causing cognitive decline and nervous system damage. The potential long-term health consequences are dire. The study associates these emerging pollutants (generated when these polymers loaded with co-contaminants are burned) with a variety of serious ailments, including cancer, lung, gastrointestinal, endocrine, and breast-related disorders.
The research vividly links high iMP levels to specific human behaviours and environmental conditions. “Winter months and evening hours showed the highest iMP levels, times when people throng to markets wearing synthetic clothing and the air is stagnant due to temperature inversion,” Prof. Drabha noted. He further pointed out that though the air is still, the friction and movement of the crowd, combined with the prevalent use of synthetic textiles, releases plastic fibres directly into the breathing zone.
The geographical factors also add to it. Prof. Drabha emphasised, “Delhi and Kolkata are geographically landlocked. Kolkata, as a city, is far from the sea. This geographical difference, along with local waste management practices and emissions, likely contributes to the higher concentrations in the landlocked cities. In these areas, pollutants struggle to disperse.”
The most pressing conclusion of this research is that it fundamentally challenges current air quality standards. Microplastics are currently not included in the regulated factors like PM2.5 and PM10 in India’s air quality framework. The researchers urge policymakers to recognise inhalable microplastics as a new, potent category of respirable pollutant, comparable to conventional particulate matter.
The path forward requires both systemic change and a fundamental shift in personal lifestyle. Prof. Darbha advised some simple but crucial changes to help people protect themselves:
- Prefer glass or steel bottles over plastic.
- Choose cotton garments, especially in winter.
- Avoid synthetic, low-cost, overly weathered clothes.
- Reduce the use of cosmetics containing unknown plasticisers.
- Avoid food stored in plastic packaging.
- Minimise the use of single-use plastics.
- Practice proper waste segregation.
He further suggested measures for policymakers:
- Creating vehicle-free market zones.
- Promoting khadi and cotton clothing.
- Improving solid waste management.
- Regulating synthetic textile production.
Today, microplastics have entered the very air we breathe. What we once thought to be just dust and smoke now includes plastic fibres carrying toxins and pathogens. It is now up to us to rethink our choices, demand better policies, and adopt cleaner habits.