London: Atmospheric scientists from the UK and India have partnered to tackle chronic air pollution, which is impacting the health of more than 20 million people in Delhi.

The Indian capital, one of the country's most densely populated metropolis, has some of the worst air pollutions of any city in the world.

Air quality experts from the University of Manchester partnered with their counterparts from the Indian Ministry of Earth Sciences (IMES), the Indian Institute of Tropical Meteorology (IITM) and the Indian Institute of Technology-Madras (IIT-M) to help drive science-based policy changes.

Their new, and ongoing, study will further identify the causes behind the pollution crisis and inform ongoing and future policy before analysing the effectiveness of the interventions.

"Air pollution in Delhi is linked to a range of factors, including heavy traffic, burnt waste and dusty air in pre-monsoon season. Crop burning is a very important source at the end of the growing season. Pollution impacts are similarly wide-ranging: lung damage, heart disease, cognitive impairment and other conditions have been associated with poor quality of air," said Professor Hugh Coe, who is a leading member of the team from the Manchester University.

One of the key measures for determining the true extent of Delhi's current pollution problem will be to measure particulate matter concentrations across the city. This detail will build a picture of the sum-total of all hazardous solid and liquid particles suspended in the air.

"The research into these is in its early stages but is already providing insights. The work we have done shows that although there are some variations in particulate matter concentrations across the city, the contributions from different sources are broadly similar," Coe said.

"This will facilitate better policy implementation since the routes to reduction via policy interventions need to be broadly similar across the city," he added.

The UK has extensive experience of conducting atmospheric chemistry measurements and carrying out computer modelling of air pollution that is world-leading. India has a rapidly growing research base in this field and a huge amount of local knowledge and understanding of the air pollution problems in Indian cities.

"Harnessing these two strengths in a joint programme that has collaborative and multi-disciplinary research at its heart is vital in making rapid progress towards improving air quality in cities across the globe," Coe noted.

Delhi Chief Minister Arvind Kejriwal has described the city's pollution as having "reached unbearable levels", with low visibility due to smog and an increase in respiratory illnesses, sparking urgent concern.

Schools across the city have recently been ordered to close, construction projects halted and residents advised to avoid outdoor activities as the air quality has reached hazardous levels.

Scientists from the Indian Institute of Tropical Meteorology have already developed the SAFAR (System of Air Quality and Weather Forecasting and Research) for advanced air quality forecasting for Delhi.

An IITM statement noted: "The collaboration with UK scientists will make a valuable addition to the SAFAR model by providing expertise in developing new parameterisation for secondary aerosol formation. The SAFAR system has recently developed ultrahigh-resolution (400 m2) emission inventory for Delhi which accounted 26 sources and concluded that the transport sector is the most dominant sector contributing 41 per cent in total particulate matter concentration.

"The industrial sector has been found to be the second most dominating factor contributing 22.3 per cent. The contributions from the power sector, biofuel sector, re-suspended dust and others are found to be 3 per cent, 5.7 per cent, 18 per cent and 11.7 per cent respectively."