Every breath of air we inhale may have not just dust and smoke as air pollutants, but also tiny plastic particles, according to a recent study by the Indian Institute of Science Education and Research (IISER), Kolkata.
These tiny particles called inhalable microplastics (iMPs) — measuring smaller than 10 micrometers — are now a significant, although invisible, component of urban air pollution.
Researchers have sounded an alarm for Kolkata, which recorded the highest average concentration of inhalable microplastics (14.23 µg per cubic metre of air), followed closely by Delhi at 14.18 µg/m³. Coastal cities such as Chennai (4 µg/m³) and Mumbai (2.65 µg/m³) were also not spared.
They estimate that an average Kolkata city resident inhales about 2.9 grams of microplastics over a lifetime, roughly equivalent to breathing in a small plastic bottle over time.
The findings say that these plastic particles, once inhaled, can penetrate deep into the lungs, enter the bloodstream, and potentially reach crucial organs. Acting as “Trojan Horses”, the airborne microplastics carry a range of harmful substances like pathogens and contaminants.
The multidisciplinary study, ‘The Dawn of a New Air Pollutant: Inhalable Microplastics as Emerging Vectors of Hazardous Contaminants and Their Implications for Human Health’, measured these particles directly at human breathing height in the crowded markets of Delhi, Kolkata, Mumbai, and Chennai.
Traditionally, PM10 and PM2.5, tiny particles from dust, smoke, and fuel, have been responsible for most air pollution. But now the new study reveals that microplastics presently account for up to 5 per cent of PM10 and 2.5 in India’s metropolitan markets.
“The majority of these polymers are derived from textiles (polyester), packaging, vehicle wear, and footwear, everyday things found in urban environments. Unlike ordinary dust, microplastics do not settle or wash away. Their lightweight aerodynamic forms keep them suspended in the air for extended periods, allowing them to traverse across cities and countries,” says the study.
The researchers have found that these inhalable particles harbour living microbes, some pathogenic or antibiotic-resistant. The team has identified bacteria and fungi such as Aspergillus fumigatus and Candida, a known respiratory pathogen, and several Bacillus species carrying antibiotic resistance and virulence factor genes.
The research team has also detected toxic plastic and cosmetics additives such as diethylphthalate (DEP) — a common plasticizer and fragrance stabilizer — that can enter the air from cosmetics, plastics, packaging materials, paints, and PVC products.
Alarmingly, Delhi, Kolkata, and Mumbai showed the highest presence of DEP in the air samples. The study says that long-term exposure to DEP may contribute to hormonal imbalances, reduced fertility, and developmental disorders.
Lead levels exceeding national safety limits
Kolkata and Delhi have also shown the highest contamination, with lead levels exceeding national safety limits. These chemical additives are linked to respiratory diseases, hormonal imbalances, and even cancers. Lead in the air, often released from degrading plastics, vehicle emissions, and industrial waste, can enter the lungs and bloodstream upon inhalation.
Chronic exposure damages the brain, kidneys, and nervous system, especially in children, causing cognitive decline and developmental delays. In plastics, lead is commonly used as a stabiliser and pigment in PVC, tires, and coatings, making it a hidden contributor to airborne toxicity.
The study also shows that a variety of ailments are associated with emerging pollutants that are generated when these polymers loaded with co-contaminants are burned. The most common ones include cancer, lung, gastrointestinal, endocrine, and breast-related disorders.
According to lead researcher Gopala Krishna Darbha, Professor at the Department of Earth Sciences (DES), “Plastic fibres shed from clothes, packaging, and footwear easily become airborne, especially in crowded markets where constant movement and friction release them. Once inhaled, these persistent pollutants can lead to a range of health problems. Our study now reveals their additional tendency to carry harmful pathogens and contaminants, further exacerbating the risk.”
What can be done?
The scientists say that people can help by reducing the use of single-use plastics, avoiding synthetic and overly weathered clothes (low cost domestically and imported reusable textiles), and supporting proper waste segregation.
They recommended promotion of greener urban spaces and encouragement of khadi (cotton) clothes and vehicle-free market areas to reduce plastic pollution in the air.