This is an emergency response to the public health situation in the national capital. More than a week after implementing the trial run, the response by Delhiites is overwhelming and compliance-level is very encouraging. There are now early signs of its impact too.

Winter pollution has peaked to unacceptable levels in the city. Cold temperature, calm and no-wind conditions trap air and pollution. Pollution builds up very quickly. The months of November and December in 2015 have shown higher number of days in severe category, four times the safe standard, which is the worst category according to the National Air Quality Index.

November had 73 per cent of days in severe category against 53 per cent in corresponding period in 2014. December 2015 had 67 per cent of days in severe category as against 65 per cent in 2014. On several consecutive days, the PM2.5 levels remained in the worst category according to the national air quality index.

Thus odd and even programme is an emergency response to arrest the high emergency peak when the overall pollution levels have gone 5 to 6 times higher than the standards. This is needed to protect public health in a city where every third child has impaired lungs.

The initial signs are encouraging. The odd-even trial has resulted in the lowest pollution peak compared to the previous high smog episodes this winter. First week of January had worse weather conditions in terms of no wind, low temperature and western disturbance. The peak pollution during odd and even trial could have been much worse. Instead, it has been much lower than the higher peaks during November and December when weather conditions were better. Lower traffic volume has certainly helped arrest the peaking of pollution in Delhi.

Moreover, during odd-even programme week, the real time pollution and wind data from the Delhi Pollution Control Committee’s monitoring stations showed that even with lower wind speed, there was declining trend in average hourly pollution. Prior to the programme, the trend was typical. As wind speed lowered, pollution increased. But with odd and even rule, the peaking of pollution could be moderated even when wind was low.

How Delhiites have contributed to pollution control? As car numbers dip, pollution load from cars are lower and per capita emissions of car users is also down. Both particulate and nitrogen oxide load from the cars has reduced substantially during odd and even programme, by as much as 40 per cent. Higher share of pollution benefits have come from reduction in diesel cars.

This has helped lower health risk as cars emit extremely toxic gases in our breathing zone. As more Delhiites have begun to car pool, higher occupancy of cars has resulted in lowering of per capita toxic emissions of car users substantially. Shift to other modes has lowered this even more. According to a recent study by IIT-Kanpur on behalf of the Delhi government, vehicles are the second highest polluters in the city. In different locations, diesel vehicles contribute hugely to PM2.5 – from 60 per cent to 90 per cent of PM2.5 from vehicles. Diesel particulates enhance lung cancer risk and premature deaths from ischemic heart disease.

Other benefits

In one stroke, this programme has erased the memory of choking congestion and stress from the minds of the people. Emissions from vehicles caught in congestion increases two times due to idling and frequent acceleration and deceleration.

Reduced congestion has also improved the journey speed for all road users, including car users.

This saves time and fuel. A study on traffic volume and speed survey carried out by the School of Planning and Architecture during the first few days of odd and even scheme has found that due to lowering of traffic volume, the travel time has reduced by 35 per cent.

Users of public transport are saving more time. Buses, autos and taxis can do more trips and carry more people due to freeing up of road space. This benefit will have to be sustained for longer-term solution to pollution problem in the city.

In other countries, duration and stringency of the programme is adjusted according to the severity and persistence of the problem.

They increase duration, penalty and minimise exemptions to further cut air pollution and congestion, and improve public transport usage.

With the small duration of programme, Paris has seen 18 per cent drop in traffic volume and 6 per cent in pollution levels. Beijing with a much longer and stringent programme, has seen 38 per cent drop in PM10.

This first ever effort to create pollution emergency response system in Delhi must be sustained. There have been attempts by detractors to derail this process by challenging this programme in the court.

This requires deeper public understanding of the importance of including vehicles in emergency action to cut personal toxic exposure and moderate peaking of pollution. Personal convenience of car users cannot take precedence over public good.

Amartya Sen on Odd and Even rule

I think the most important thing that we learn from the odd and even (scheme) is that it is not just odd and even, which I of course salute, and I am delighted that Delhi population has lived up to the expectations. But it is important to think of a problem before it arises.

Unfortunately in Delhi, we have had the kind of pollution which is not easy to see and so it generates a sense that it is not there. We certainly have fog but not the kind of thick smog that Beijing has even though our air is probably worse than that, in many ways definitely worse than that.

(The writer is Head, Air Pollution and Clean Transportation Programme, Centre for Science and Environment, New Delhi)