India is currently facing air pollution challenges, which have led to significant health concerns. A team of scientists at the Laboratory for Atmospheric Chemistry at the Paul Scherrer Institute, or PSI for short creates, constructs, and manages extensive, intricate research facilities, which are accessible to both national and international researchers focussing on research in matter and materials, energy and environment, and human health. Additionally, PSI is dedicated to educating and preparing future scientists and researchers.PSI has recently conducted an important study aimed at better understanding the harmful particles present in the air over northern India. The results of this study are expected to offer valuable insights into this critical issue and contribute towards finding viable solutions.

According to the World Health Organization, around 1.3 million people die every year in India because of polluted air. The Indian government is trying to tackle this problem with its National Clean Air Programme. But to do this effectively, decision-makers need to understand where the pollution is coming from and how harmful it is to health. This new study, published in the journal Nature Communications, provides this important information for the first time.

The study focused on New Delhi, which has the highest concentration of air pollution in the world. Previous research had already shown that the chemical processes in New Delhi's skies are different from those in other major cities. This time, the researchers wanted to understand the sources of pollution and how certain substances affect health.

The study found that incomplete combustion, such as burning biomass or waste, is a major cause of air pollution. This includes burning cow dung for heating and cooking, which produces a lot of harmful particles. Old vehicles, especially tuk-tuks and motor scooters with inefficient engines, also contribute to the problem.

To understand how pollution varies in different areas, the researchers expanded their network of measuring sites. They analyzed samples from New Delhi and surrounding areas, as well as from Kanpur, a city southeast of New Delhi. By studying the chemical composition of the particles, they were able to determine their oxidative potential, which is a measure of how harmful they are to health.

The study found that particles from incomplete combustion have a high oxidative potential, which can lead to asthma, inflammation, and other health problems. These particles are emitted locally in India, but they also come from regional sources. This highlights the need for both local and national measures to tackle air pollution.

The research in New Delhi was funded by the Swiss Agency for Development and Cooperation. Although the first phase of the programme is coming to an end, there is still much work to be done. According to programme leader André Prévôt, India needs strict measures, long-term monitoring, and societal change to improve air quality. It will take time, but with the right actions, environmental conditions in northern India can improve.