Toxic threat: East Delhi's air loaded with excessive heavy metals, reports study

As Delhi gears up to embrace winter and combat smog, a new study published in the International Journal of Environmental Studies has highlighted the presence of heavy metals such as chromium, copper, zinc, molybdenum, and lead in PM2.5 particles in East Delhi and other regions, as reported by The Times of India. The research investigated heavy metal exposure in six districts: East Delhi, Jaisalmer, Ludhiana, Visakhapatnam, Panchkula, and Patiala.

The study aimed to measure the Heavy Metal Exposure Index (HEI) and found that East Delhi recorded the highest HEI before the COVID-19 lockdown. After the lockdown, Ludhiana had the highest HEI, followed by East Delhi. Researchers collected samples from various areas in East Delhi, including Mayur Vihar, Dilshad Garden, and Laxmi Nagar, during 2019 and 2020.

The study identified cadmium, arsenic, chromium, copper, zinc, molybdenum, and lead in most PM2.5 samples across all six districts. The highest HEI value was found in Ludhiana (21.78), followed by East Delhi (21.45) and Panchkula (10.74). The median HEI value stood at 8. The study noted a decrease in HEI in East Delhi and Jaisalmer during the lockdown period.


The researchers emphasized the adverse health effects of heavy metals. "Heavy metals such as lead and manganese are neurotoxic and affect children's cognitive and motor development. Arsenic, cadmium, nickel, and chromium are carcinogenic, posing cancer risks to humans," the study stated. It also mentioned the harmful effects of copper and zinc on lung health.

Lead author Kanhaiya Lal highlighted the health risks associated with PM2.5 particles containing heavy metals and organic compounds. "These harmful substances, found in PM2.5 particles in cities like Delhi, Ludhiana, Patiala, Panchkula, and Visakhapatnam, can trigger oxidative stress—an imbalance between the body's antioxidant defenses and the production of reactive oxygen species—which can significantly increase the risk of respiratory and cardiovascular diseases in the population," Lal told The Times of India.

The study also found higher concentrations of sulfate and nitrate in Patiala's PM2.5 samples compared to other districts. The sulfate concentration in Patiala was significantly higher than in East Delhi, Jaisalmer, and Panchkula. The nitrate concentration was also elevated in Patiala compared to East Delhi, Jaisalmer, and Panchkula, potentially due to soil dust containing nitrogenous fertilizers.