With the winter and the festive season set to begin in around a month’s time, the annual discourse on the air quality crisis in Delhi and the National Capital Region (NCR) is set to begin. Apart from meteorological considerations, over which we have little control, increasing pollution from anthropogenic activities (particularly vehicular emissions) continues to worsen the problem. But there’s some new insight that can help us address the problem better. The Real Urban Emissions Initiative (TRUE), founded by the FIA Foundation and the International Council on Clean Transportation (ICCT), worked with authorities in Delhi and Gurugram to complete a comprehensive remote sensing study that measured over 100,000 vehicles across 20 sites. The data presented in the report reveals ways to tackle the problem.
Importantly, remote sensing technology for pollution control is not new to India. Kolkata pioneered its use in 2009, and government agencies like the International Centre for Automotive Technology conducted pilot programmes in 2017. The National Green Tribunal has also advocated its implementation to the Central Pollution Control Board since 2015, but the technology is yet to be widely adopted. It’s encouraging, then, that the Supreme Court of India recently reiterated its 2018 and 2019 directives to the ministry of road transport and highways (MoRTH) to implement remote sensing technology in the NCR.
India is the world’s third most polluted country and home to the most polluted Capital, according to the World Air Quality Report 2023 by IQAir. Over the past 25 years, various institutions, including the apex court, the National Green Tribunal, and MoRTH have implemented numerous measures to curb emissions from road transport. Despite these efforts, the rising number of vehicles has thus far largely offset the progress made. However, there was a significant leap in terms of vehicle emissions in April 2020, when India transitioned directly from Bharat Stage (BS) IV to BS VI emission standards.
The current vehicle emissions testing regime has two primary parts. The first is the type-approval stage, where the government grants (or not) approval for a manufacturer to introduce a tested model into the market. The second is the widely known in-use compliance test, or the pollution-under-control certification (PUCC). This is needed periodically and applies to every internal combustion engine vehicle on the road. There are limitations to both. The type-approval test, which now incorporates real-driving emissions testing using a portable emissions measurement system, is expensive for mass-scale monitoring. Meanwhile, the PUCC is conducted in idle conditions and doesn’t capture key transport pollutants like nitrogen oxides (NOx) and particulate matter.
Monitoring and enforcement programmes can supplement periodic emissions inspections to ensure consistent vehicle performance in real-world conditions. Remote sensing technology can non-intrusively screen tailpipe emissions on a large scale and help identify highly polluting vehicles.
The TRUE Initiative helps cities worldwide develop air quality and climate policies using independent real-world vehicle emissions data. The study in Delhi and Gurugram, conducted from December 2022 to April 2023, measured exhaust emissions of NOx, carbon monoxide (CO), hydrocarbons (HC), and ultraviolet (UV) smoke, a proxy for particulate matter from two- and three-wheelers (3W), private cars, taxis, light goods vehicles, and buses.
The analysis revealed that India’s leap from BS IV to BS VI norms led to significant reductions in tailpipe emissions across all vehicle types. This underscores the benefit of promoting cleaner technologies and stricter regulations and points to the potential of introducing BS VII norms in the future. The study also found disparities in emissions across different vehicle segments, with commercial vehicles like light goods vehicles, taxis, 3Ws, and buses emitting substantially more than private vehicles.
In comparing captured real-world emissions with laboratory limits (the type-approval limits) set by MoRTH, it was found that real-world emissions can be multiple times higher (15–25 times higher in a few cases). While the vehicles in the study are not required to meet lab limits on the road, this significant difference emphasises how performance that qualifies for type-approval certification does not reflect the ultimate impacts on air quality and human health. Even the BS VI vehicles, which were the cleanest of those measured, had higher emissions during real-world operations.
The NCR has seen a major shift towards compressed natural gas (CNG) as an alternative to traditional petroleum fuels. This was done largely to reduce particulate matter emissions. However, this study’s data challenges the perception of CNG as a clean fuel solution. High NOx emissions are particularly concerning because NOx contributes to the formation of secondary particulate matter and ozone. Thus, relying on CNG as a transitional step towards zero-emission vehicles may not be suitable for regions like Delhi and Gurugram, where air quality is already severely compromised.
It’s also clear from the study’s results that PUCC limits do not reflect real-world emissions. This underscores the need to complement PUCC tests with real-world monitoring technologies. The Automotive Industry Standard (AIS) 170, in draft since 2020, needs to be finalised and notified by MoRTH to enable effective use of remote sensing.
Finally, accelerating the transition to zero-emission vehicles, especially in commercial segments, is crucial to combat vehicular emissions in Delhi NCR. Several policy options are available to achieve this, including implementing a supply mandate for zero-emission vehicles and establishing low-emission zones to complement existing policies. The Commission for Air Quality Management is well positioned to lead this effort in the NCR.
Anirudh Narla is researcher, and Amit Bhatt is managing director (India), ICCT.The views expressed are personal
