Capital trap: New study shows where in Delhi your lungs have least chance of escaping nanoparticles

A new study has revealed that Delhi residents are inhaling millions of harmful nanoparticles daily, especially near roads, ToI reported on January 14. The joint research by the Physical Research Laboratory, Ahmedabad, and Delhi Technological University focused on nanoparticles (PM1 or smaller) and their impact on pedestrians, the report (by Kushagra Dixit)

The study's findings emphasise the need for measures to improve Delhi's air quality and protect public health.

Researchers discovered people in Delhi inhale 10-18 million nanoparticles daily while walking roadside. Nanoparticle levels near roads are 30% higher than in areas farther from traffic. These tiny particles, smaller than PM2.5 and PM10, pose a greater health risk due to their size. They make up 60-80% of the total particle number concentration in Delhi's air.


The study, published by Elsevier, titled "Seasonal Variation of Particle Number Concentration in a Busy Urban Street with Exposure Assessment and Deposition in Human Respiratory Tract", found these particles deposit deeply in the lungs' alveolar regions. The Rohini district in North Delhi served as the study location, examining the impact across all seasons.

“Using a computerized model for analyzing the deposition, the study revealed that more nanoparticles are deposited in the alveolar regions of the human lungs. Because these nanoparticles are about 500 times smaller than the size of human hair, they penetrate deep into the lungs” and “have the potential to penetrate our bloodstream” and can be deposited in different parts of the body, “including the brain”, the report pointed out.

The research team included Rajeev Kumar Mishra, associate professor at Delhi Technological University, S. Ramachandran, senior professor at the Physical Research Laboratory, and Kanagaraj Rajagopal, a research scholar at Delhi Technological University.

The study highlights higher nanoparticle concentrations near roadsides. "So, for a city like Delhi, residential zones adjacent to the road will automatically have higher exposure for the residents. The people working or living near the road, such as police personnel, street vendors, drivers, motorcyclists, delivery personnel and the urban poor living near the road, are suspected to be more vulnerable to the nanoparticles," he told the newspaper.

The study also suggests that the policy formulation towards the concentrations of these particles is required for reducing the nanoparticle emissions from the engine sources to mitigate the impacts of these particles on the atmosphere and human health," Mishra added.