No PUC checks on key pollutants PM2.5, NOx

Pollution checking centres in the national capital region (NCR) do not check how much a diesel car emits two of the most harmful pollutants — nitrogen oxide (NOx) and ultra-fine PM 2.5 particles — according to data and experts who say the current system to certify vehicles as non-polluting is based on “obsolete” technology.

Data from Delhi government’s transport department between September and November this year shows that approximately 800,000 pollution-under-control (PUC) certificates were issued across 943 certified centres in the national capital. However, none of these certificates clear a vehicle for the emission of NOx and PM 2.5.

The problem lies with machines that are used to measure emissions in exhaust gases of diesel vehicles. While all European and American cities, along with most Asian cities, use technology to track NOx, PM, carbon monoxide (CO) and hydrocarbons (HC), Delhi’s PUC centres are equipped to measure only the latter two pollutants in the case of petrol vehicles. For diesel, they measure the opacity of the smoke through what is known as the Hartridge Smoke Unit (HSU), an archaic proxy for particulate matter content.

“Smart monitoring of on-road emissions has become necessary and inevitable in Delhi as most of our on-road fleet has become BS-IV compliant and we will move to BS-VI technology for new vehicles next year. Delhi cannot afford to remain moribund with only one archaic PUC programme that was originally designed for older technologies,” said Anumita Roychowdhury, executive director (research and advocacy) at the Centre for Science and Environment (CSE).

BSIV, or Bharat Stage IV, refers to vehicle technology and mechanics that are an improvement over older vehicles in terms of emissions.

According to a study by United States (US)-based International Council of Clean Transportation (ICCT), NOx — which has been linked to health conditions such as breathing difficulty and headaches — and PM2.5 particles — which are believed to cause heart and lung conditions — lead to 180,000 premature deaths every year. Almost two-thirds of these are believed to be in India, the report published in February said.

Among the 100 major urban centres assessed for vehicular emission-related deaths globally, New Delhi ranked sixth in the ICCT study.

Experts now suggest the use of new, remote-sensing technology to deal with the problem.

The Supreme Court had, in a 2018 order, asked the Delhi government to test the possibility of introducing ‘remote sensing’ to replace the PUC system. Remote sensing involves sensors placed on the side of the road or at a height to transmit a laser beam to measure exhaust emissions via ‘spectroscopy’ as vehicles pass by.

This can measure exhaust plume, and detect opacity, nitric oxide, carbon monoxide, PM levels, hydrocarbons, and carbon monoxide in 0.5 seconds in the exhaust plumes of vehicles. The apex court had observed that PUC monitoring was not just an old technology, but only 23% of Delhi’s vehicles were turning up for PUC tests.

“The remote sensing technology was experimented after the SC order but no work has been done in the area since then,” a senior Delhi government official said.

Last month, the state government implemented the odd-even road rationing scheme in the city in order to reduce the number of vehicles on the road.

For nearly a month beginning in November, Delhi and the adjoining regions were covered in smog as the air quality index (AQI) shot up to levels not seen in two years. The deterioration triggered anger among people and earned administration officials rebuke from courts, which said that the country’s national capital cannot be allowed to be turned into a gas chamber

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