Amit Bhatt & Anirudh Narla
Ever since motor vehicles were introduced in India, its citizens, and to a large extent its authorities have limited knowledge of what comes out from the tailpipe of these vehicles when they are in actual use. This is because the existing Pollution Under Control (PUC) testing procedure is done when vehicle is idle and not under operation. Also, it does not measure key pollutants of concern from road transport – PM and NOx – which contribute greatly to air pollution and are harmful to human health.
To overcome this and get a better idea of on-road emissions, Delhi has joined a selective list of cities across the globe that are piloting remote sensing technology to understand real-world emissions from motor vehicles.
The study led by the International Council on Clean Transportation (ICCT), as part of The Real Urban Emissions (TRUE) initiative, is being executed presently at around 15 points in New Delhi and Gurugram in collaboration with the Delhi Transport Department and the Gurugram Administration.
The Central Motor Vehicles Rules, 1989, mandates vehicles in India to undergo emissions testing at the stage of type approval for every model being introduced into the market and later at an individual vehicle level, as part of the post-sale periodical technical inspection. These tests are carried out at authorized PUC testing centers certified by the transport department.
During the test, a probe is inserted into the tailpipe to measure the level of pollutants emitted by the vehicle. For petrol and CNG/LPG vehicles, the test assesses only carbon monoxide, hydrocarbon, and air-fuel ratio, while for diesel vehicles, a smoke density test is performed, and the vehicle is issued a pass or fail certificate based on the results.
However, these tests are limited in scope and are performed only when a vehicle is idle. Furthermore, the PUC tests fail to capture the impact of driving skill, road condition, age of vehicle, maintenance, fuel type, etc. on emissions.
It is also important to note that from April 2023, Real Driving Emissions (RDE) testing is also expected to be introduced. In this, the real world vehicular emissions testing and monitoring has been inducted into the type approval and the in-service conformity tests to be carried out by the testing agencies of Indian Government.
This however, does not cover the annual PUC test, which will continue to be an idle emissions test, carried out at authorised PUC testing centres by the transport departments of individual states.
Remote sensing technology
Unlike PUC, Remote sensing devices (RSDs) measure exhaust emissions from motor vehicles as they are driven past the remote sensing device on streets and highways.
The emissions are measured spectroscopically by casting a narrow infrared (IR) and ultraviolet (UV) beam of light through the trailing exhaust of passing motor vehicles and a series of detectors measure the amount of transmitted light at characteristic wavelengths absorbed by the pollutants of interest (includes CO, HC, NO, NO2, PM, CO2).
As the emissions are measured, the video camera captures a digital image of the license plate and the sensors record the speed and acceleration of the vehicles. The emissions, weather conditions, slope, speed and acceleration data as well as the license plate image are merged within less than a second to complete a measurement record which is then stored in a computer database for future analysis and reporting.
The up-to-date measurements of Delhi NCR fleet will provide a detailed insight into the in-use emissions of vehicles. The data and evidence can further help with changes in policy decisions that reduce the impact of the highest emitting vehicles, improve air quality, and public health.
Researchers plan to measure real-world emissions of more than 100,000 in-use vehicles for this TRUE study.
Delhi NCR region is one of the most polluted locations in India, and the transport sector contributes significantly to fine PM (PM2.5) and coarse PM (PM10) levels during peak pollution season.
Therefore, controlling air pollution in cities is crucial, and measuring real world pollution from motor vehicles is an essential aspect of this. The government has implemented various measures to ensure that vehicles comply with prescribed emission standards and shift to zero-emissions vehicles.
The TRUE study is, therefore, an opportunity to collect detailed data on real-world emissions and inform policies that could significantly improve air quality in India.
Amit Bhatt, is Managing Director (India), ICCT & Anirudh Narla is Associate Researcher, ICCT.
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