As the national capital grapples with recurring toxic smog every winter, the Union government has taken another step to curb one of the persistent sources of air pollution in the region — diesel generator (DG) sets. In a fresh directive aimed at cleaning Delhi’s hazardous winter air, the Railway Board has ordered four railway zones operating within the Delhi-NCR region to replace or convert all non-compliant diesel generators in accordance with the norms issued by the Commission for Air Quality Management, commonly known as CAQM.

The instructions, formalized in a letter issued on November 18, were addressed to the Northern Railway, North Central Railway, North Western Railway, and West Central Railway. These are the major operational divisions that manage trains, stations, maintenance depots, and essential infrastructure across the National Capital Region, making their compliance crucial in mitigating emissions. The Railway Board noted that in the absence of immediate replacement options, the railway zones must either convert the existing DG sets to dual-fuel mode — allowing them to shift to cleaner fuel sources — or equip them with Retrofit Emission Control Devices, known as RECDs, that can significantly reduce particulate matter and nitrogen oxides released during generator operation.

This move follows a stringent communication from the Delhi Pollution Control Committee on October 26. The DPCC, in its letter to the Railway Board chairman, urged strong and swift action to ensure full compliance with CAQM’s mandates regarding generator emissions. The committee highlighted that Delhi’s pollution levels, particularly during winter, routinely exceed all prescribed standards of air quality. The city’s air pollution emergency, marked by dense haze, health advisories, and school closures, has drawn judicial scrutiny and public outrage — making the reduction of all controllable pollution sources an urgent priority.

Diesel generators remain a major contributor to local air pollution in Delhi, especially during periods of power instability or planned maintenance shutdowns. These units are widely used across commercial and institutional establishments, including hospitals, metro stations, mobile towers, business hubs, and essential service nodes such as railway stations. With over 20 million residents dependent on continuous transport and essential public services, railway facilities often rely on DG sets during power supply disruptions. However, diesel combustion emits high amounts of fine particulate matter (PM2.5 and PM10), carbon monoxide, hydrocarbons, and black carbon — pollutants directly linked to severe respiratory and cardiovascular illnesses.

Recognizing these risks, Delhi has been designated an Air Pollution Control Area under the Air Act of 1981, giving authorities expanded powers to regulate harmful emissions and mandate cleaner operational measures. The CAQM, specifically tasked with overseeing air quality improvements in Delhi-NCR and surrounding regions, issued detailed guidelines in 2023 and updated them in 2024 regarding the regulated use of DG sets. These guidelines classify the generators by capacity — below 19 kV, between 19 kV and 125 kV, and up to 800 kV — and prescribe necessary compliance actions, ranging from emissions filters to enhanced monitoring systems.

The DPCC, citing these directives, pointed out that units under railway jurisdiction also fall under the categories strictly governed by CAQM regulations. Their letter emphasized that all institutions in Delhi must transition to either compliant DG technology or operational upgrades that support emission reduction. With diesel generator usage intensifying during winter power load peaks, especially in public transport infrastructure, regulators see this sector as an important target with high immediate environmental impact.

Beyond the mandatory transition to compliant DG systems, the DPCC highlighted the continuous need for vigilance and enforcement. The letter reminded authorities that air quality in the region consistently breaches safety thresholds, often reaching levels considered extremely hazardous by global health standards. Several major pollutants are recorded at multiple times the permissible limits, posing immediate health dangers. The national capital routinely ranks among the world’s worst cities for air quality, drawing international criticism and pressure for policy reforms.

With every winter comes a familiar cycle: crop residue burning in neighboring states, construction dust, vehicular emissions, industrial pollutants, and low wind speeds combine to trap harmful particulates close to the ground. This creates a toxic blanket over the city, forcing children, the elderly, and vulnerable patients indoors, while straining the public health system. Efforts such as halting high-emission vehicles, banning construction temporarily, and closing schools have provided only temporary relief. Authorities recognize that deeper, structural changes are required — including the modernization of power backup and industrial machinery.

The railways, as a major public-serving agency, are also expected to lead by example. Many railway stations and technical facilities still rely on older diesel generator technology that does not conform to upgraded emission norms. The installation of Retrofit Emission Control Devices can curtail particulate emissions by up to 70 to 90 percent depending on the device type — a significant improvement. Similarly, dual-fuel systems enable generators to run primarily on cleaner fuels such as natural gas while using diesel only for ignition, minimizing toxic emissions during prolonged operation.

In addition to environmental protection, the directive promotes long-term modernization. Moving toward renewable, grid-based, or hybrid power backup systems could further eliminate dependence on diesel in the future. The Indian Railways has recently accelerated electrification of its tracks and locomotives nationwide, making the pollution-control push for non-traction equipment part of a broader sustainability strategy.

However, implementation challenges remain. Replacing or upgrading DG systems involves infrastructural overhaul, procurement of compliant units, availability of skilled technicians, and budget allocations. Some heritage or space-constrained railway stations may also face engineering hurdles in retrofitting new technology. Yet, environmental authorities insist that compliance cannot be delayed, given the life-threatening severity of toxic air exposure in NCR.

For Delhi’s residents, each initiative counts. While diesel generators are only one among numerous pollution sources, reducing their footprint contributes to improving winter air quality incrementally but meaningfully. Experts caution that results may take time, yet coordinated actions across all government bodies are essential to prevent further degradation of the region’s air index.

The Railway Board’s directive marks a firm step toward aligning the sector with environmental norms and strengthening accountability. The success of these measures will depend on timely implementation, monitoring, and adequate support from both central and state administrations.

As winter approaches and visibility once again drops to smog-filled haze, such regulatory demands reflect a growing realization: mitigating Delhi’s pollution crisis requires sustained structural transformation. Cleaner energy practices in critical public infrastructure like the railways are not just technical upgrades but an urgent public health necessity — shaping the future of the nation’s capital and its millions of citizens who deserve breathable air.