Study by IIT-Delhi reveals significant drop in particulate matter in the city after targeted interventions

A study conducted by the Indian Institute of Technology (IIT) Delhi reveals a significant reduction in particulate matter levels in three urban clusters of Delhi through targeted interventions on dispersed sources of pollution.

The study, led by Professor Sagnik Dey from IIT Delhi's Centre for Atmospheric Sciences, collected data at 15-minute intervals across Jahangirpuri, Rohini, and Karol Bagh. It shows significant reductions in PM2.5 levels: 26.6% in Jahangirpuri, 15.7% in Rohini, and 15.3% in Karol Bagh, according to a release.

PM2.5, or particulate matter 2.5, refers to tiny particles in the air that are 2.5 micrometres or less in diameter. This fine particular matter is less than the thickness of a strand of human hair.

The study titled 'The Impact of the Dispersed Sources Program on Local Air Quality' showcases the effectiveness of addressing dispersed pollution sources, including unpaved roads, illegal dumping of construction waste, garbage burning, and broken footpaths. These are considered as major contributors to pollution.

Conducted between July 2023 and March 2024, the study used portable low-cost sensors calibrated against high-grade monitors to measure the effectiveness of targeted interventions under the Dispersed Sources Program. The programme, managed by the Municipal Corporation of Delhi (MCD) and guided by the Commission for Air Quality Management, is a pivotal part of Delhi's efforts to tackle urban air pollution, said the release.

The study found a strong correlation between localised interventions and reduced PM2.5 levels in Delhi, with a clear difference-of-difference methodology comparing affected and unaffected areas.

The Dispersed Sources Program, launched in Delhi in 2020, focuses on mitigating two types of issues: long-term issues such as unpaved roads and broken footpaths, which require more time and budget, and short-term issues including illegal dumping of construction debris and garbage, which can be resolved more swiftly.

The programme's success under the National Clean Air Action Plan offers potential for other Indian cities, recommends the study.

After Delhi, the programme has expanded to Ghaziabad, Gurugram, Noida and Faridabad in the National Capital Region. It now operates across 13 cities in Delhi, Haryana, Uttar Pradesh, and Bihar. Over 2.3 lakh pollution-related issues have been resolved in Delhi-NCR alone.

"The substantial reductions in PM2.5 levels locally we have observed are promising and underscore  the efficacy of this data-driven approach. Our research provides robust evidence that addressing both short-term and long-term pollution sources can yield substantial and sustained  improvements in air quality," said Prof Sagnik Dey, Professor at the Centre for Atmospheric Sciences, IIT Delhi.

"We strongly recommend that non-attainment cities across the nation implement this programme to foster transformative changes, assess local air quality improvement, and strengthen air  quality management," he added.

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The mobile applications MCD 311, NOIDA ONE, and Ghaziabad 311 have played a vital role in efficiently identifying, tracking, and resolving pollution issues, said the professor, in a presentation.

The portable low-cost sensors used in the study provided real-time data every 15 minutes, enabling researchers and city officials to monitor the immediate effects of local interventions.

"The study by IIT Delhi highlights the success of MCD and A-PAG’s (Air Pollution Action Group) collaborative efforts, showcasing how targeted interventions, such as repairing potholes, managing  construction waste, and improving road infrastructure, can lead to notable air quality improvements in the  city," said Tariq Thomas, Additional Commissioner, MCD.

A-PAG works with the centre and state governments and municipal bodies to aid their efforts in fighting air pollution.

"MCD has actively worked to reduce pollution at the community level by implementing dust control  measures, enhancing waste management systems, and engaging with residents to create cleaner, healthier  neighborhoods. We are optimistic that this programme can foster broader, more sustainable environmental  impact for Delhi,” added Thomas.