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Pollution comes from trucks industries diesel generators and open burning

The discussions over India's deteriorating air quality started two years ago after a WHO report deemed Delhi as the most polluted city in the world. This led to discussions among the public about the consequences of being exposed to high concentrations of pollutants.

On the downside, this has also created a lot of panic and distrust, and it is feared that we may miss the broader picture and long-term solutions in the confusion and desperation to find a quick fix. There are many sources of particulate matter (PM) emission in Delhi and the National Capital Region (NCR).

The source apportionment studies carried out for the region identified vehicles, biomass burning and secondary particulates to have the major share in ambient PM2.5 concentrations (particles with size less than 2.5 micrometers, which are able to reach deep into the lungs). Vehicles are certainly an important contributor to the problem of pollution and require to be controlled.

Several studies assessed the impact of the odd-even scheme on pollutant concentrations and concluded a limited reduction of 5-13% in pollutant
concentrations. It is mainly because the share of private cars towards prevailing PM concentrations is small (less than 5%) and, even after accounting for additional reductions due to less idling by vehicles and reduced road dust re-suspension emissions, the impact could be limited.

While in winters, when pollution is high, even this percentage reduction translates into a significant absolute change in PM2.5 concentrations, in summers when the pollution levels are relatively low, the absolute reductions will be lower. This clearly indicates the need to look at other sources like trucks, inter-state buses, two-wheelers, industries, power plants, DG sets, open agricultural residue burning in NCR.

The air pollution issue in Delhi cannot be expected to be solved by looking at the city in isolation and taking remedial actions just within its boundaries. Modelling studies at the Energy and Resources Institute (TERI) have suggested that the whole Indo-Gangetic plain is heavily polluted by particulate matter and the NCR is one of the hotspots. There are over 13 million vehicles in the NCR, with more than 8 million in Delhi itself.

While cars have shifted to advanced BS-IV emission norms in 2010, most heavy vehicles have remained at BS-III due to their requirements to move out of NCR where BS-IV quality fuel is not available. It is now heartening to see that the government has decided to move to the most advanced vehicular standards (BS-VI norms) on a pan-India basis by 2020. The options of retrofitting and fleet modernisation need to be explored with the introduction of low sulphur fuel in India by 2019,to reduce pollution from older, in-use vehicles. The public transport system needs to be enhanced significantly.

In an alarming bad-air situation like in Delhi, the public transport should ideally be based on electric rather than fossil fuel-based engines. There are other sectors that demand simultaneous action. While diesel engines in vehicles are being talked about so much, the diesel generators using similar technologies are generally neglected. These are in use for many hours of the day in the adjoining towns of Delhi, where power supply is a major issue.

It is time to think about 24x7 supply of electricity to the region to cut down the usage of diesel generators which are a significant source of PM and NOx emissions. It is generally observed that landfills catch fires during summers and a lot of uncollected refuse is burnt for volume eduction.

The ban on open burning of refuse needs to be enforced with the use of mobile technology, through which pictures and coordinates of violations can be sent to the concerned authorities to take action. Air pollution is a complex, multi-pollutant and multi-sectoral issue. Hence, this needs consistent attention, and calls for regular five-year, air-quality management plans focusing on different sectors in NCR.

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