New Delhi: As the Delhi government moves ahead with plans to develop “smog-eating” surfaces in the city, environmental experts on Wednesday warned that such technological interventions should not replace efforts to curb pollution at its source.

Delhi Environment Minister Manjinder Singh Sirsa on Wednesday announced that the government has signed a memorandum of understanding with IIT Madras to identify and develop photocatalytic or “smog-eating” surfaces, which will be tested in select parts of the city as a pollution-control measure.

Environmental activist Bhavreen said pollution control requires stronger systems and enforcement rather than the addition of new chemical coatings.

“Anything applied on surfaces contains chemicals. Adding more substances in an already polluted environment may not help. What is needed is stronger enforcement and action to cut emissions at the source,” she told PTI.

Clean air advocate and author of ‘Breathing Here Is Injurious to Your Health’, Jyoti Pande Lavakare, echoed similar concerns, stressing the need to strictly enforce existing laws, including action against open waste burning and the use of firecrackers. “Everyone, including children and the elderly, is breathing polluted air. This irreversibly harms health and triggers serious chronic diseases over time,” she said.

Lavakare also flagged the Union Environment Ministry’s July decision to ease norms for installing flue gas desulphurisation systems at coal-based thermal power plants, calling it a setback to efforts aimed at controlling pollution at its source.

“Real solutions are being rolled back and replaced by mere optics,” she said.

Citing a peer-reviewed study published in 2023, another environmental expert said similar photocatalytic technologies have shown limited impact in real urban conditions despite encouraging laboratory results.

The study, titled ‘Potential Ambient NO2 Abatement by Applying Photocatalytic Materials in a Spanish City and Analysis of Short-term Effect on Human Mortality’, examined the use of such coatings in Alcobendas near Madrid.

Analysing air quality and mortality data from 2001 to 2019, the study found that while titanium dioxide-based coatings demonstrated high pollution-removal potential in controlled settings, their real-world impact reduced ambient nitrogen dioxide levels by only about three per cent.

It also said that the cost of implementing the technology outweighed the pollution damage costs saved, making it economically inefficient as a standalone measure.

Factors such as limited sunlight, night-time inactivity, dust accumulation, ageing of surfaces and air movement were cited as reasons for the low effectiveness. The study concluded that meaningful improvements in air quality require reducing emissions at the source, particularly from traffic.

In winter months, Delhi’s air pollution peaks, with AQI levels remaining in the ‘very poor’ category above 300 on most days and often rising to the ‘severe’ category beyond 400, affecting even healthy individuals.

On Wednesday, Delhi’s air quality was in the ‘very poor’ category, with the 24-hour average Air Quality Index (AQI) standing at 334 at 4 pm, according to the Central Pollution Control Board (CPCB).

According to the CPCB, an AQI between 0 and 50 is considered ‘good’, 51-“100 ‘satisfactory’, 101-“200 ‘moderate’, 201-“300 ‘poor’, 301-“400 ‘very poor’ and 401-“500 ‘severe’.